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Publication Number: FHWA-HRT-10-037
Date: October 2010

Step Frequency Ground Penetrating Radar Characterization and Federal Evaluation Tests

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Figures

Figure 1. Chart. SF GPR emissions and their characteristics. The schematic diagram shows the operating parameters of a step frequency ground penetrating radar (SF GPR) in a graphical format where the frequency bandwidth of the system is plotted on the y-axis, and the data collection time is plotted on the x-axis. The parameters shown in the plot include the number of frequencies used (N), the equally spaced frequency steps between each transmitted frequency, and the dwell time during which the system measures a response at each frequency. The features in the plot appear as a series of steps that range from low frequency to high frequency, where each step has a duration corresponding to its dwell time.

Figure 2. Diagram. SF GPR emissions characterization test configuration. The physical test apparatus used to make step frequency ground penetrating radar (SF GPR) emission measurements is shown schematically from a side view and from a plan view. In the side view, the transmitting SF GPR antenna array under test hangs from a plastic mounting frame 9.84 ft (3 m) from the emission measurement antenna. The emission measurement antenna is a yellow trapezoid, and the wide side is on the bottom and pointed towards the antenna array. The SF GPR antenna array is 1.15 ft (0.35 m) high and 2.18 ft (0.665 m) wide and hangs 0.82 ft (0.25 m) above the ground. In the plan view, the transmitting SF GPR antenna array under test is shown with its long axis oriented along a 0-degree angle, while six additional orientation angles from 30 to 180 degrees in 30-degree increments, illustrating each antenna orientation that is used for emission measurements. The antenna array is a 2.16-ft (0.66-m)-wide and 5.94-ft (1.8-m)-long yellow-orange rectangle. The emission measurement antenna is a yellow rectangle 9.84 ft (3 m) from the center of rotation of the SF GPR antenna.

Figure 3. Diagram. Orthogonal position of antenna array relative to figure 2. This figure shows the physical test apparatus used to make step frequency ground penetrating radar (SF GPR) emission measurements, which is also shown in figure 2. This figure shows the orthogonal side view and the plan view, with the long axis of the antenna array oriented along the 90-degree direction with a horizontal polarization in both the side view and the plan view. The six additional orientation angles from 0 to 180 degrees in 30 degree increments illustrate each antenna orientation that is used for emission measurements. In the orthogonal view, the SF GPR antenna array is a yellow rectangle, with its long axis pointed towards the measurement antenna. Because the antenna array is over 9.84 ft (1.8 m) long and is 1.97 ft (0.6 m) wide, the distance between the antenna array and the near side of the emission measurement antenna rectangle is approximately 6.9 ft (2.1 m) when the antenna array is positioned in this orientation. The distance to the center of the SF GPR antenna array remains the same. This short distance (significantly less than 9.84 ft (3 m)) has an impact on many of the emission measurements.

Figure 4. Photo. SF GPR testing at the FAA Technical Center. This photograph shows a test apparatus at the Federal Aviation Administration (FAA) Technical Center, which is depicted schematically in figure 2 and figure 3. The antenna is a yellow trapezoid in its cross section and a rectangle when viewed from the top. The mounting hardware is a 3-inch (76.2-mm) white polyvinyl chloride pipe shaped like a rectangular box, with the pipe forming the edge of the box. The step frequency ground penetrating radar (SF GPR) antenna array is 10 inches (254 mm) above a sand pit and oriented at a 30-degree angle. A log periodic emission measurement antenna is directed toward the SF GPR antenna array, and the wiring connected to the emission measurement antenna is being adjusted by test personnel. The log periodic emission measurement antenna is shaped like an isosceles triangle, with a wire from the middle of the base to the point and with smaller wires perpendicular to the central wire going to the edge of the triangle. The test site is located in a rural location with woods and a small shed in the distance.

Figure 5. Photo. SF GPR test site at the FAA Technical Center. This photograph shows the test apparatus at the Federal Aviation Administration (FAA) Technical Center, which is also seen in figure 4. This figure shows the center from a distance. The step frequency ground penetrating radar (SF GPR) antenna array is positioned 10 inches (254 mm) above a sand pit and oriented at a 30-degree angle. A log periodic emission measurement antenna is directed toward the SF GPR antenna array. Three test personnel are pictured using a power spectrum analyzer to make emission measurements. A support vehicle used to transport test equipment, two large inactive communications towers, and a small shed are pictured in the background.

Figure 6. Diagram. Antenna array with a bank of 23 transmitter and 23 receiver elements. The step frequency ground penetrating radar antenna array is illustrated in a schematic diagram. The transmitter portion of the array is represented by 23 yellow triangular elements of 3 different sizes arranged in a closely spaced, linear fractal pattern. In this pattern, two small equilateral triangles are paired with one medium-sized equilateral triangle twice the small triangles’ height. This set of three triangles then alternates with one large triangle, which is three times the height of the smallest triangle. In the transmit array bank, which is labeled Tx, the first two triangles are labeled T1 and T2, and the last transmit antenna triangle is labeled T23. Similarly, in the receive antenna array bank, which is labeled Rx, the first two antennas are labeled R1 and R2, and the last antenna element is labeled R23. The receiver portion of the antenna array is in the same geometric pattern as the transmitter portion of the array, but it is oriented in a direction that is rotated 180 degrees relative to the transmitter portion of the array.

Figure 7. Graph. EIRP peak measurement values for horizontal measurement antenna orientation and maximum transmitter emission orientation without emission notching. This figure shows emission measurements collected at the Federal Aviation Administration (FAA) Technical Center corresponding to maximum peak frequencies without notching for horizontally polarized measurement antennae. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. Among many measured values that are observed below National Telecommunications and Information Administration (NTIA) criteria, a few isolated measurement peaks appear to exceed NTIA criteria. However, these isolated peaks are generally attributed to transient ambient phenomena occurring at the FAA Technical Center. A few other peak measurement values between 1,300 and 1,610 MHz are slightly above NTIA criteria.

Figure 8. Graph. EIRP peak measurement values for vertical measurement antenna orientation and maximum transmitter emission orientation without emission notching. This figure shows emission measurements collected at the Federal Aviation Administration (FAA) Technical Center corresponding to maximum peak frequencies without notching for vertically polarized measurement antenna. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. Among many measured values that are observed below National Telecommunications and Information Administration (NTIA) criteria, a few isolated measurement peaks appear to exceed N TIA criteria. However, these isolated peaks are generally attributed to transient ambient phenomena occurring at the FAA Technical Center. A few other peak measurement values between 1,300 and 1,610 MHz are slightly above NTIA criteria.

Figure 9. Graph. EIRP RMS measurement values for horizontal measurement antenna orientation and maximum transmitter emission orientation without emission notching. Root mean squared (RMS) measurement results are presented in this figure for a horizontally polarized measurement configuration without emission notching. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. Below 960 MHz, a significant number of ambient peaks exceed emission measurement criteria. These same peaks are also observed in the SF GPR emissions measurement data and are therefore attributed to ambient phenomena. A few peaks from 1,200 to 1,610 MHz slightly exceed National Telecommunications and Information Administration (NTIA) criteria. Ambient measurements below 140 MHz are significantly higher than NTIA criteria.

Figure 10. Graph. EIRP RMS measurement values for vertical measurement antenna orientation and maximum transmitter emission orientation without emission notching. Root mean squared (RMS) measurement results are presented in this figure for a vertically polarized measurement configuration without emission notching. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. Below 960 MHz, a significant number of ambient peaks exceed emission criteria. These same peaks are also observed in the SF GPR emissions measurement data and are therefore attributed to ambient phenomena. A few peaks are slightly above the National Telecommunications and Information Administration (NTIA) criteria. Ambient measurements below 140 MHZ are significantly higher than NTIA criteria.

Figure 11. Graph. EIRP peak measurement values for horizontal measurement antenna orientation and maximum transmitter emission orientation with emission notching. This figure shows emission measurements collected at the Federal Aviation Administration (FAA) Technical Center for maximum peak frequencies with notching for data that correspond to frequency notch configuration A1 for horizontally polarized measurement antennae. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of emissions notching. The overall level of the response data is reduced slightly relative to figure 7. Note that the y-axis is in decibels referenced to 1 milliwatt; therefore, a reduction in the response data corresponds to a vertically downward shift of the response curve.

Figure 12. Graph. EIRP peak measurement values for vertical measurement antenna orientation and maximum transmitter emission orientation with emission notching. This figure shows emission measurements collected at the Federal Aviation Administration (FAA) Technical Center for maximum peak frequencies with notching for data that correspond to frequency notch configuration A1 for vertically polarized measurement antenna. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of emissions notching. The overall level of the response data is slightly reduced relative to figure 8. Note that the y-axis is in decibels referenced to 1 milliwatt; therefore, a reduction in the response data corresponds to a vertically downward shift of the response curve.

Figure 13. Graph. EIRP RMS measurement values for horizontal measurement antenna orientation and maximum transmitter emission orientation with emission notching. Root mean squared (RMS) measurement results are presented in this figure for a horizontally polarized measurement configuration with notching for data that correspond to frequency notch configuration A1. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. The overall level of the response data is slightly reduced relative to figure 9. Note that the y-axis is in decibels referenced to 1 milliwatt; therefore, a reduction in the response data corresponds to a vertically downward shift of the response curve. Only eight blue data points representing SF GPR emissions are above the red criteria line.

Figure 14. Graph. EIRP RMS measurement values for vertical measurement antenna orientation and maximum transmitter emission orientation with emission notching. Root mean squared (RMS) measurement results are presented in this figure for a vertically polarized measurement configuration with notching for data that correspond to frequency notch configuration A1. Equivalent isotropic radiated power (EIRP) is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. The overall level of the response data is slightly reduced relative to figure 10. Note that the y-axis is in decibels referenced to 1 milliwatt; therefore, a reduction in the response data corresponds to a vertically downward shift of the response curve. The number of blue points above the criteria line decreased from about 42 to 22, and these generally exist much lower above the criteria line.

Figure 15. Screen shot. General measurement data summary table (part 1 of 2). This figure is a screen shot of a table that summarizes the parameters associated with many of the general measurement data files collected. The table describes the frequencies measured, the measurement antenna, the resolution bandwidth, the video bandwidth, the orientation of the step frequency ground penetrating radar antenna array, the orientation of the measurement antenna, the presence or absence of notching, and the measurement type.

Figure 16. Screen shot. General measurement data summary table (part 2 of 2). This figure is a continuation of the table in figure 15. It is a screen shot of a table that summarizes the parameters associated with many of the general measurement data files collected. The table describes the frequencies measured, the measurement antenna, the resolution bandwidth, the video bandwidth, the orientation of the step frequency ground penetrating radar antenna array, the orientation of the measurement antenna, the presence or absence of notching, and the measurement type.

Figure 17. Screen shot. Federal system data summary table (part 1 of 2). This figure is a screen shot of a table that summarizes the parameters associated with many of the Federal system data files collected. The table describes the frequencies measured, the measurement antenna, the resolution bandwidth, the video bandwidth, the orientation of the step frequency ground penetrating radar antenna array, the orientation of the measurement antenna, the presence or absence of notching, and the measurement type.

Figure 18. Screen shot. Federal system data summary (part 2 of 2). This figure is a continuation of the table in figure 17. It is a screen shot of a table that summarizes the parameters associated with many of the Federal system data files collected. The table describes the frequencies measured, the measurement antenna, the resolution bandwidth, the video bandwidth, the orientation of the step frequency ground penetrating radar antenna array, the orientation of the measurement antenna, the presence or absence of notching, and the measurement type.

Figure 19. Graph. Outdoor peak emission measurement with horizontal polarization without notching. Follow-up test results are presented corresponding to a peak horizontally polarized measurement configuration. No emission notches are implemented for this measurement configuration. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the intentional emission spectrum of the system under test (140–3,000 MHz) except for one area between 960 and 1,000 MHz, which is slightly above NTIA criteria. Ambient emission measurement levels are generally substantially below SF GPR emission measurement levels within the measurement range of the system. Some spikes occur in the ambient measurements that reach a level equal to the SF GPR emission measurements, but they rarely exceed SF GPR levels in the intentional emission frequencies of the SF GPR. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 20. Graph. Outdoor peak emission measurement with horizontal polarization with A1 notch configuration. Follow-up test results are presented corresponding to a peak horizontally polarized measurement configuration. Emission notch A1 is implemented for this measurement configuration, and corresponding notches are all observed in the step frequency ground penetrating radar (SF GPR) emission measurement data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system. Some spikes occur in the ambient measurements that substantially exceed SF GPR emission measurements, but they do not exceed NTIA criteria. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 21. Graph. Outdoor peak emission measurement with horizontal polarization with A2 notch configuration. Follow-up test results are presented corresponding to a peak horizontally polarized measurement configuration. Emission notch A2 is implemented for this measurement configuration, and corresponding notches are all observed in the step frequency ground penetrating radar (SF GPR) emission measurement data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Between 960 and 1,000 MHz, SF GPR emissions are measured slightly above NTIA criteria. Ambient emission measurement levels are generally substantially below SF GPR emission measurement levels within the measurement range of the system. Some spikes occur in the ambient measurements that substantially exceed SF GPR emission measurements, but they do not exceed NTIA criteria. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 22. Graph. Outdoor peak emission measurement with horizontal polarization with A3 notch configuration. Follow-up test results are presented corresponding to a peak horizontally polarized measurement configuration. Emission notch A3 is implemented for this measurement configuration, and corresponding notches are all observed in the step frequency ground penetrating radar (SF GPR) emission measurement data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Between 960 and 1,000 MHz, SF GPR emissions are measured slightly above NTIA criteria. Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system. Some spikes occur in the ambient measurements that substantially exceed SF GPR emission measurements, but they do not exceed NTIA criteria. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 23. Graph. Outdoor peak emission measurement with vertical polarization without notching. Follow-up test results are presented corresponding to a peak vertically polarized measurement configuration. No frequency notches are implemented for this measurement configuration. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). An isolated peak appears at approximately 850 MHz that substantially exceeds NTIA criteria. It only appears in two of the four vertically polarized follow-up measurements; therefore, it is an intermittent ambient phenomenon. Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 24. Graph. Outdoor peak emission measurement with vertical polarization with A1 notch configuration. Follow-up test results are presented corresponding to a peak vertically polarized measurement configuration. Emission notch A1 is implemented for this measurement configuration, and corresponding notches are all observed in the step frequency ground penetrating radar (SF GPR) emission measurement data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). An isolated peak appears at approximately 1,210 MHz that slightly exceeds NTIA criteria. Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 25. Graph. Outdoor peak emission measurement with vertical polarization with A2 notch configuration. Follow-up test results are presented corresponding to a peak vertically polarized measurement configuration. Emission notch A2 is implemented for this measurement configuration, and corresponding notches are all observed in the step frequency ground penetrating radar (SF GPR) emission measurement data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). An isolated peak appears at approximately 850 MHz that substantially exceeds NTIA criteria. It only appears in two of the four vertically polarized follow-up measurements; therefore, it is an intermittent ambient phenomenon. Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 26. Graph. Outdoor peak emission measurement with vertical polarization with A3 notch configuration. Follow-up test results are presented corresponding to a peak vertically polarized measurement configuration. Emission notch A3 is implemented for this measurement configuration, and corresponding notches are all observed in the step frequency ground penetrating radar (SF GPR) emission measurement data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 27. Graph. Outdoor RMS emission measurement with horizontal polarization without notching. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. No emission notch is implemented for this measurement. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line showing the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 28. Graph. Outdoor RMS emission measurement with horizontal polarization with A1 notch configuration. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. Emission notch A1 is implemented for this measurement, and corresponding notches are apparent in the response data upon inspection of the data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 29. Graph. Outdoor RMS emission measurement with horizontal polarization with A2 notch configuration. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. Emission notch A2 is implemented for this measurement, and corresponding notches are apparent in the response data upon inspection of the data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 30. Graph. Outdoor RMS emission measurement with horizontal polarization with A3 notch configuration. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. Emission notch A3 is implemented for this measurement, and corresponding notches are apparent in the response data upon inspection of the data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are graphed: a green line represents the ambient emissions measured without any SF GPR antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of emissions notching. Step frequency ground penetrating radar (SF GPR) emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 31. Graph. Outdoor RMS emission measurement with vertical polarization without notching. Follow-up test results are presented corresponding to a root mean squared (RMS) vertically polarized measurement configuration. No emission notch is implemented for this measurement. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 32. Graph. Outdoor RMS emission measurement with vertical polarization with A1 notch configuration. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. Emission notch A1 is implemented for this measurement, and corresponding notches are apparent in the response data upon inspection of the data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 33. Graph. Outdoor RMS emission measurement with vertical polarization with A2 notch configuration. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. Emission notch A2 is implemented for this measurement, and corresponding notches are apparent in the response data upon inspection of the data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz).Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of the emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz, (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 34. Graph. Outdoor RMS emission measurement with vertical polarization with A3 notch configuration. Follow-up test results are presented corresponding to a root mean squared (RMS) horizontally polarized measurement configuration. Emission notch A3 is implemented for this measurement, and corresponding notches are apparent in the response data upon inspection of the data. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Three lines are shown on the graph: a green line represents the ambient emissions measured without any step frequency ground penetrating radar (SF GPR) antenna emissions, a blue line represents the SF GPR emissions, and a red line represents the maximum emissions allowed in that segment of the frequency band. Generally, the ambient emissions are the lowest line, the SF GPR emissions are in the middle, and the maximum allowed emissions are at the top. In addition, horizontal blue lines are placed on the x-axis in the areas of emissions notching. SF GPR emission levels are below National Telecommunications and Information Administration (NTIA) criteria throughout the majority of the intentional emission spectrum of the system under test (140–3,000 MHz). Ambient emission measurement levels are generally substantially below the SF GPR emission measurement levels within the measurement range of the system, but some ambient spikes occur below 960 MHz. Between 960 and 1,610 MHz, SF GPR and ambient measurements are both observed to be slightly above NTIA criteria. At 2,250 MHz, an ambient spike is observed. Below 140 MHz (outside the intentional emission frequencies of the SF GPR), ambient and SF GPR emissions exceed NTIA criteria.

Figure 35. Graph. Indoor emission measurements using vertically polarized measurement antenna at low frequencies. In the figure, detailed emission measurements are presented corresponding to frequencies between 50 and 200 MHz using the following measurement modes: peak, root mean squared (RMS), and quasipeak. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Above 140 MHz, all intentional emissions are compliant with National Telecommunications and Information Administration (NTIA) criteria shown on the plot. A clear boundary is observed in the emission data above 140 MHz where emissions transition from unintentional below 140 MHz to intentional above 140 MHz. Above 140 MHz, individual frequency responses are observed that correspond to each step the step frequency ground penetrating radar transmits. Below 140 MHz, unintentional emissions do not follow a clear pattern, and the majority of emissions are above NTIA criteria.

Figure 36. Graph. Indoor emission measurements using horizontally polarized measurement antenna at low frequencies. Detailed emission measurements are presented corresponding to frequencies between 50 and 200 MHz using the following measurement modes: peak, root mean squared (RMS), and quasipeak. Equivalent isotropic radiated power is shown on the y-axis in decibels referenced to 1 milliwatt (dBm), and frequency is shown on the x-axis in megahertz (MHz). Above 140 MHz, all intentional emissions are compliant with National Telecommunications and Information Administration (NTIA) criteria shown on the plot. A clear boundary is observed in the emission data above 140 MHz, where emissions transition from unintentional below 140 MHz to intentional above 140 MHz. Above 140 MHz, individual frequency responses are observed that correspond to each step the step frequency ground penetrating radar transmit. Below 140 MHz, unintentional emissions do not follow a clear pattern, and the majority of emissions are above NTIA criteria.

Equations

Equation 1. Field strength as a function of field strength in dBm plus adjustments. Field strength parenthesis decibel times microvolt end parenthesis equals field strength parenthesis decibel referenced to 1 milliwatt end parenthesis plus 107.

Equation 2. Refined definition of field strength to dbMuV/M as a function of field strength adjusted by antenna factor and cable loss in terms of a unit length. Field strength parenthesis decibel times microvolt divided by m end parenthesis equals field strength parenthesis decibel times microvolt end parenthesis plus antenna factor plus cable loss.

Equation 3. Conversion from units in terms of unit length to units in terms of dBm. EIRP in decibel referenced to 1 milliwatt equals field strength parenthesis decibel times microvolt divided by m end parenthesis minus 95.2.

Appendix E Figures

Figure 1. Graph. Ambient emissions between 50 MHz and 200 MHz are presented corresponding to the outdoor test configuration used for follow-up testing.

Figure 2. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (outdoor test configuration). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 3. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 200 MHz to 1,000 MHz, (outdoor test configuration). Peak measurements are observed to be relatively stable between -30 dBm and -50 dBm. RMS emissions are observed to be relatively stable at approximately -70 dBm with a few elevated emission features observed intermittently. No notching is implemented for this vertically polarized measurement.

Figure 4. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 1,000 MHZ to 6,000 MHz, (outdoor test configuration). Peak measurements show a distinct change from consistently elevated emissions at approximately -40 dBm below 3,000 MHz to approximately -50 dBm above 3,000 MHz. RMS measurements are relatively stable throughout the entire measured range and average around -62 dBm. No notching is implemented for this vertically polarized measurement.

Figure 5. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (outdoor test configuration). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement. No notching is implemented for this horizontally polarized measurement.

Figure 6. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 200 MHz to 1,000 MHz, (outdoor test configuration). Peak measurements are observed to be relatively stable between -30 dBm and -40 dBm. RMS emissions are observed to be relatively stable at approximately -65 dBm with a few elevated emission features observed intermittently. No notching is implemented for this horizontally polarized measurement.

Figure 7. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 1,000 MHZ to 6,000 MHz, (outdoor test configuration). Peak measurements show a distinct change from consistently elevated emissions at approximately -40 dBm below 3,000 MHz to approximately -50 dBm above 3,000 MHz. RMS measurements are relatively stable throughout the entire measured range and average around -62 dBm. No notching is implemented for this horizontally polarized measurement.

Figure 8. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (outdoor test configuration). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. Notch configuration A1 is implemented for this vertically polarized measurement. A notch between 160 and 175 MHz is apparent in the peak measurement data.

Figure 9. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 200 MHz to 1,000 MHz, (outdoor test configuration). Peak measurements are observed to be relatively stable between -30 dBm and -40 dBm. RMS emissions are observed to be relatively stable at approximately -65 dBm with a few elevated emission features observed intermittently. Notch configuration A1 is implemented for this vertically polarized measurement. Multiple notches are apparent in the peak measurement data.

Figure 10. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 1,000 MHZ to 6,000 MHz, (outdoor test configuration). Peak measurements show a distinct change from consistently elevated emissions at approximately -40 dBm below 3,000 MHz to approximately -50 dBm above 3,000 MHz. RMS measurements are relatively stable throughout the entire measured range and average around -62 dBm. Notch configuration A1 is implemented for this vertically polarized measurement. Multiple notches are apparent in the peak measurement data.

Figure 11. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (outdoor test configuration). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. Notch configuration A1 is implemented for this horizontally polarized measurement. A notch between 160 and 175 MHz is apparent in the peak measurement data.

Figure 12. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 200 MHz to 1000 MHz, (outdoor test configuration). Peak measurements are observed to be relatively stable between -30 dBm and -40 dBm. RMS emissions are observed to be relatively stable at approximately -65 dBm with a few elevated emission features observed intermittently. Notch configuration A1 is implemented for this horizontally polarized measurement. Multiple notches are apparent in the peak measurement data.

Figure 13. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 1,000 MHZ to 6,000 MHz, (outdoor test configuration). Peak measurements show a distinct change from consistently elevated emissions at approximately -40 dBm below 3,000 MHz to approximately -50 dBm above 3,000 MHz. RMS measurements are relatively stable throughout the entire measured range and average around -62 dBm. Notch configuration A1 is implemented for this horizontally polarized measurement.

Figure 14. Graph. Ambient emissions between 50 MHz and 200 MHz are presented corresponding to the indoor test configuration used for follow-up testing.

Figure 15. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 0-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 16. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 30-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 17. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 60-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 18. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 90-degree orientation). Intentional emissions observed above 140 MHz have less structure than at other orientations, while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 19. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 120-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 20. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 150-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 21. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 180-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this vertically polarized measurement.

Figure 22. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 0-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 23. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 30-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 24. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 60-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 25. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 90-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 26. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 120-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 27. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 150-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 28. Graph. Peak and RMS SF GPR emission measurements are shown for the range from 50 MHz to 200 MHz, (indoor test configuration, 180-degree orientation). Structured intentional emissions are observed above 140 MHz while no clear pattern in the emissions data is observed below 140 MHz. No notching is implemented for this horizontally polarized measurement.

Figure 29. Photo. Photograph of outdoor test configuration, including B1823 SF GPR antenna and horn measurement antenna (side view). The SF GPR antenna is suspended above the ground by two white saw horses. The ground surface is gravel. A lake is visible in the background. The picture is taken from the side of the measurement antenna and the SF GPR antenna. The side of the measurement antenna is visible in the right of the picture while the end of the SF GPR antenna suspended from the two saw horses is visible on the left of the picture.

Figure 30. Photo. Photograph of outdoor test configuration, including B1823 SF GPR antenna with its long axis in line with the measurement direction of the white biconic measurement antenna. The SF GPR antenna is suspended above the ground by two white saw horses. The ground surface is gravel. A lake is visible in the background. The picture is taken from the side of the measurement antenna and the SF GPR antenna.

Figure 31. Photo. Photograph of outdoor test configuration, including the yellow trapezoidal B1823 SF GPR antenna and white horn measurement antenna sitting about four feet above the ground on a three legged yellow tripod (boresight view). The SF GPR antenna is behind the measurement antenna and resting perpendicular to its line of sight. The SF GPR antenna is suspended above the ground by two white saw horses. The ground surface is gravel. A lake is visible in the background. The picture is taken from behind the measurement antenna with the SF GPR antenna on the far side of the measurement antenna.

Figure 32. Photo. Photograph of indoor test configuration, including anechoic chamber. The yellow trapezoidal SF GPR unit is resting on a set of grey blocks sitting on a beige floor. The walls are patterned with white square emissions absorbing blocks.

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