What is the best antenna to use to monitor aircraft with the SDS 100
For aircraft, take a look at the RH77CA
. It does well for Vhf-high and Uhf. The civilian aircraft band is 118MHz to 137MHz. It's not the best choice for 700 & 800MHz systems, like most public safety trunked radio systems, but neither is it deaf in those bands. With a decent signal, it will do the job on your local system Heart of Texas Regional Radio System
. Note that the RH77CA is about 15 inches long.
I prefer the RH789
. It's a telescoping antenna, and has markings on the side suggesting how far to extend it for specific frequency bands. Collapsed down, it works well for most bands, or extend it to enhance Vhf-high & aircraft band reception. You should order the BNC version, and use the SMA to BNC adapter that came with the scanner. The SMA versions of these do not seat correctly on the recessed SMA connector or the SDS100, and do not have the o-ring to maintain the water resistant design of the scanner. (Note- These are available from a number of retailers, including Amazon, ScannerMaster, and others. I used the Universal Radio link as it was the handiest.)