I’m currently using the below 1090 antenna for both piaware and fr24. would like to add 978.
Does anyone have a freq plot for this antenna?
Has anyone tried this? results?
I know there is a dedicated antenna. What I am asking is how the 1080 antenna will perform at 978Mhz.
Thanks
tim
Never tried a 1090 Mhz antenna for 978 Mhz, but theoretically, it will not give optimum performance. However the two frequencies being close to each other, it should not perform too bad either.
If you can make a DIY antenna, try a Spider or Cantenna with whip/radials/can-height 76mm instead of 69mm to tune it to 978 MHz.
If it were a low gain antenna then that might be true.
But if i’m not mistaken the FA 1090 antenna is quite poor at 978 MHz.
@abcd567 Put the FA 1090 on your VNA and check the SWR curve and compare it with the quarter wave, that should give you an idea 
That was my thought as well, since it’s close. I don’t want another antenna on my roof, but if I can pull both from single antenna, might be worthwhile. I really don’t know if there is any filtering in the mast, likely just length tuned to the wavelength. I can take some attenuation.
I am not aware of construction of AirNav antenna, but Flightaware 1090 MHz antenna definitely does not have any built-in filter. It is a wire collinear with phasing coil and decoupling sleeve.
Flightaware 1090 Mhz Antenna from inside
CLICK ON IMAGE TO SEE LARGER SIZE
I did ping radarbox on a bode plot. I would hope they don’t consider it proprietary and would consider sharing. They might be fearful of affecting their 978 antenna sales, lol.
Good find on the antenna inside view.
That ADSB Exchange antenna looks identical to FA antenna.
monozygotic twins, aka identical twins 
I wondered if the difference was only marketing
If they market that as “Dual band” probably the FA is the same… Probably has a drop in gain at 978MHz.
Kind of irrelevant, since those planes fly low and they disappear behind Earth curvature very quick.
They look almost identical from outside, but inners should be somewhat different, as FA is only 1090 MHz while ADX is 1090+978 Mhz.
Are they really different? Or is just marketing?
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