Also take a look at the RH789. It's a telescoping antenna, with markings on the antenna showing how many segments to extend for various frequency bands. While it's available in both an SMA mount as well as a BNC, you'd need to get the BNC version, and use the SMA->BNC adapter that came with the scanner. The SMA mount on the SRH-789 would not properly fit the recessed antenna connector on the scanner. You could use the BNC version on either your SDS100 or the PSR-500.ive heard great things about the Diamond RH77CA
The Smiley Antenna 5/8 Slim Duck 160, hands down. I've got two (one I've had since the late 1980s), and you can't beat them. I bought one with the proper connector for the Icom F3161DT-RR railroad radio I use for RR monitoring and it's superior in every respect. The other has a BNC connector and goes on whichever scanner I feel like using at that moment.I have a SDS100 and GRE 500....What's a good antenna for monitoring railroad in the Columbus Ohio area? thanks
They're helically wound so yes, they are physically shortened. Even so, every one of the band-specific 5/8 Slim Duck antennas I have works considerably better than a 1/4 wave, and light years of improvement over a stock scanner or HT antenna.Smiley calls their antenna 5/8 which should be 46 inches long but thiers are only 9 inches. So it must be extremly shortened and not much effective antenna area left. Any tuned antenna to a narrow frequency range are better than an antenna for another frequency or a broadbanded one. It feels like it probably could be more efficient if it where a 1/4 antenna that was shortened. Their claim of 6dBd gain are ridicolous. A full lenght 5/8 antenna optimum maximized could have at most a 4dBd gain.
Remember that a 1/4 antenna has more omni direction vertically than a 5/8 that compress the directivity in hight to focus more to the horizon and gets more critical of an upright position. That's why you find very few gain antennas for portable use.