HAM Radio 101

Airplane Scatter: How Hams are Taking Radio Signals Skyward to Ping Airplanes

If you’re a “been there, done that” kind of ham who has bounced a radio signal off everything from the moon to a meteor to the Aurora Borealis, we bet you’ll want to add aircraft scatter to your ever-growing and already impressive list. Or if you’ve already pinged an airplane—consider us all ears to hear how it went!

The idea behind the propagation process is to transmit a radio signal from your setup into the skies above to bounce directionally off an in-flight airplane with the ultimate goal of expanding the range of your radio communication.

Contacts are made using high frequency to VHF to microwave bands with expected reach of about 500 miles (800 km) away—even if you’re operating portable from a mountainous region like the Alps. But there are a few ham heroes out there, like VK7MO and VK3HZ, who have used 10 and 24 GHz signals on microwave bands to ping airplanes with even more range—we’re talking 523 miles or 842 km—which is just downright impressive and extremely tricky to do! (Read a rundown of their experience here.)

Range and contact length are influenced by all sorts of things, though, so there will always be variables like flight level, plane size (“hello,” Boeing 747s), the crossing time of the straight line between two stations, or even the band worked (the higher the frequency, the bigger the time crunch to QSO). Plus, while a plane may seem massive while grounded, it’s just a little speck in the sky to target with your signal, in a contact that typically takes under a minute to successfully do. 

And, of course, there’s the additional challenge of finding a plane to bounce a signal off of in the first place. Luckily, there are a lot of programs that can help you track aircraft like FlightRadar24, RTL-SDR, and AirScout created by DL2ALF, or apps like PlanePlotter mobile for Android or AirScope for Apple. All public real-time info that’s accessible to any ham who’s interested.

Or you can receive info on-air (the same type you’ll find online) that’s sent out directly from aircrafts using Mode S or ADS-B (Automatic Dependent Surveillance-Broadcast System) technology. Mode S transponders will send out packets of information to requesting ground stations or unsolicited packets of info called “squitters.” ADS-B sends out “squitters” as well. Both use the 1090 band to operate.

And if you need equipment to get you started, DX Engineering can help with antennas, VHF/UHF transceivers, including the Icom IC-9700 VHF/UHF/1.2 GHz Transceiver with optional 10 GHz transverter, and more! Not into airplane scatter? Check out the CSN Technologies S.A.T. Self-Contained Antenna Tracker and have a blast operating amateur radio satellites.

We’d love to hear or see the setups you use and hear stories about your experiences with airplane scatter. Feel free to share in the comments below. 73!

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