Just modified a Raspberry Pi 3 to accept an external WiFi/Bluetooth antenna via U-FL socket.
Have recorded a new range peak in dump1090 running the Mode-S Beast together with a G7RQG antenna – 488km.
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.
Here is another one. Huge thing this time, designed for 433MHz, polarization RHCP. For dimensions etc. see design description below.
Here is another quadrifilar helix antenna design, this time for ADSB (aircraft mode-S transponder) reception at 1090 MHz. Unlike other antenna types this antenna has a spherical coverage with 120° 3dB beamwidth and estimated peak gain of 4.6dBi at 1090MHz.