I know this is a stretch, but has anyone found a dual band antenna that does reasonably well on ADS-B and AIS? 1090 MHz and 162 MHz? I would like to run one antenna, one down lead and two radios. I found a suitable band splitter, but I’m looking for an antenna. I know the VSWR might not be great, but sometimes an antenna made for one band works decently for RX only on another band. Has anyone found anything that does both well?
A discone antenna has a very wide bandwidth. They are often used for receive only scanner type setups.
If the height above ground was good, it should work well enough. Make sure the splitter isolates the dongles well or their noise could cause problems.
This is the band splitter I plan to use to separate the two. It should give me better isolation and less loss than a simple 3.5 dB splitter. ebay.com/itm/281943124342
I run one of my ADS-B stations on a discone, which I also use for 2 meter (144 MHz) and 440 MHz amateur radio work, both transmit and receive.
The duplexer I use is the Comet CB-413B, which splits the signal into a low band, 1.3 - 460 MHz, and a high band 860 MHz - 1.4 GHz. You can find them on eBay, such as:
ebay.com/itm/Comet-CF-413B-D … 2075155475
Also sold by places such as Ham Radio Outlet hamradio.com/index.cfm
They cost around $60 list (more than the $5 for the sat unit) but they’re built for transmit as well as receive. I can transmit 50 Watts on either band and the ADS-B side isn’t bothered at all.
A side note about discone antennas: the radiation pattern changes with frequency, tilting up as the frequency increases. Not too much of a problem for ADS-B.
I run one ADS-B system on the discone, and the other on a commercial co-linear. The reported numbers for the co-linear are much higher than the discone. Both systems are using identical hardware: Flightaware filters and SDRs, Raspberry Pi 3. If anything the feedline to the discone is a little lower loss than that to the co-linear (both 50 Ohm). Both antennas are at about the same height, on different parts of the roof.
Interesting, the discone sees some birds close in that the commercial antenna doesn’t.
bob k6rtm
The higher the gain, the flatter the doughnut. A discone has no gain, so its pattern will be very round, up and down. That’s why it hears overhead so well. At the southern tip of Florida, I care more about planes at the horizon, so I’m going to want a high gain, very flat doughnut pattern to get the most gain to the horizon. So what I’m looking for is like a 144/1200 high gain base antenna, just 162/1090 instead. Or something that works fairly well at that range for RX only. Like what’s a 1/4 wave at 545 MHz is 1/2 wave at 1290. Over simplification, but it could work.
Thanks