On Oct 29, 12:37*am, bumper wrote:
Andrzej,

From what I've seen earlier bricks came with the ADS-B/PCAS antennas you discribe. Later bricks are shipping with a shorter dipole that is more tuned for the 1090 Mhz frequency. The only differance in the two antennas is that the radials on the 1090 antenna are a little shorter (gueestimating each radial is 3/16" shorter). Flarm had to special order the higher frequency antennas . . . they are from the same company that makes the 916 Mhz antenna, but are not an off-the-shelf item.

One could heat the little ribber cap to remove them and then lop off a bit of the radial with a Dremmel cut-off wheel after doing the math. But in the real world, the 916 Mhz antenna should work pretty well as receive is much less critical than transmit. That and the fact that the signal you are receiving is being transmitted at 200 watts.

bumper

I would not think PowerFlarm would special order anything if it was
not required. Why would they change the antenna later, maybe because
of poor PCAS performance? If PCAS estimates distance through signal
strength (as I was told) then how would they be able to calculate the
strength with two different antennas?