ADS-B for receiving the flight data is on 1090 MHz. So a quarter wavelength is about 6.8 cm. However, I cut my copper wires a little longer so that I can still tune afterwards.

What do you need:

  • A socket,perhaps a PL, BNC or SMA
  • Rigid copper wire, 5 x 8 cm (I stripped mine from a 3 core power cable).
  • optional are cable lugs and screws (instead you can solder the copper wires directly to the socket)

I have decided for the SMA socket, because I want to go later anyway on SMA. Otherwise, I have found four different screws and nuts, in the same diameter.

  • Next, I attached the cable lugs to the SMA socket with the screws. Alternatively, you can solder the copper wires directly to the socket.
  • Then I stripped 5 chum wires from a power cable and shortened them to 8 cm.
  • Then I wetted all the copper wires with tin.
  • Next, I soldered four copper wires to the lugs.
  • After that I soldered the fifth copper wire to the inner conductor of the SMA socket.
  • Finally, I connected the antenna to an analyzer and found that the copper wires were too long.
  • I shortened all copper wires to 6.7 cm and had a SWR of 1:21 on 1090 MHz. I measured including the cable lugs.
  • The antenna is located in the middle of Berlin on the balcony on the second floor and has a range of about 280 km.