Today I tried my G7RGQ antenna together with a NooElec NESDR Smart stick connected to the ADSB Raspberry Pi. I put the antenna and the stick on the roof and had it running for a while. To my surprise the performance was not as expected. I needed the same a gain setting to archive results comparable to my QFH antenna with 6m coax to the receiver. Again, I removed 6m of coax, around 6dB attenuation, but results were ain’t better. Took everything down again and disassembled the setup for testing.
After successfully testing of my G7RGQ antenna here my built details:
With above dimensions the antenna is tuned to about -22dB return loss at 1090MHz when placed inside the PVC tube.
I took the opportunity for some experiments with gain settings in dump1090-fa while testing a new built antenna for the ADSB receiver. I compared my previously built QFH antenna to a G7RGQ omni directional antenna that I built last week. Second object of test was a 10m active USB cable (from Amazon).
I recently forked dump1090-fa on Github and modified the web code for indication of military or civil aircraft and highlighting aircrafts marked interesting. Required for this modification is an extended dump1090 JSON aircraft database that is available for download here. Outcome looks like this:
In upgrade 1 I described how to add a GPS to the ADSB receiver for a precise clock in the Raspberry Pi. Here is another description how to add a graph in the the ADSB receiver portal for monitoring clock performance.