I believe he is referring to receive antennas. I use an old Lake tuner I got from eBay. You can use about any broadband tuner, such as the MFJ 900, and similar. You don't need a fancy tuner with meter and other extra features. These are designed for hams for transmitting. The simple matchers have just two knobs. You can also use a tuner with a built in preselector. I have one made by MFJ, but I found out in my situation, my simple Lake tuner with band switch worked better. There is also a ton of schematics and construction details online, if you want to roll your own. To use, just tune for maximum signal on freq. You want to hear. If tuning through a band, just tune for maximum background noise. If you can find one, the Lake tuners were designed for SWL, but they were made in the UK, and are hard to find on this side of the pond.