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Q&A Is there a way to reliably measure antenna return loss outside a lab?

The RSSI detector in the receiver is the best field tool. In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientati...

posted 3y ago by TonyStewart‭  ·  edited 2y ago by TonyStewart‭

Answer
#5: Post edited by user avatar TonyStewart‭ · 2022-08-16T15:56:08Z (over 2 years ago)
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive. **It simply used a Schottky diode on the return path to a DMM to measure the reflected wave after calibration with lab equipment.** You could use a stripline directional coupler or a hybrid 3 dB splitter or anything direction to measure return loss for tuning to a minimum.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • **The 2nd best tool is a 3dB splitter to measure the return peak voltage with a diode and DMM but requires calibration.**
  • - When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive. **It simply used a Schottky diode on the return path to a DMM to measure the reflected wave after calibration with lab equipment.** You could use a stripline directional coupler or a hybrid 3 dB splitter or anything direction to measure return loss for tuning to a minimum.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
#4: Post edited by user avatar TonyStewart‭ · 2022-08-14T16:59:25Z (over 2 years ago)
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive. **It simply used a Schottky diode on the return path to a DMM to measure the reflected wave after calibration with lab equipment.** You could use a stripline directional coupler or a hybrid 3 dB splitter or anything direction to measure return loss for tuning to a minimum.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
#3: Post edited by user avatar TonyStewart‭ · 2022-08-13T17:01:24Z (over 2 years ago)
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
#2: Post edited by user avatar TonyStewart‭ · 2022-08-13T17:00:22Z (over 2 years ago)
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
  • **The RSSI detector in the receiver is the best field tool.** In Windows I had a tool that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple degrees and the results might change from -74 to -84 dBm and result in occasional errors at 54 Mbps.
  • When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive.
  • You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.
#1: Initial revision by user avatar TonyStewart‭ · 2021-06-06T07:44:56Z (over 3 years ago)
When I was doing the same in ‘77 I found that the return loss was depending on people walking into the lab and thought I had just invented a remote intrusion alarm from the reflected waves at multiple wavelengths. This was after tuning the antenna for RL>20 dB so the directional coupler was very sensitive.

You can also have a thermal sensitivity problem as well as a sensitivity to the shift in effective wavelength from reflections.