Antenna tuners are not magic pixie dust for out of whack antennas. Way back when I was studying for my first ham ticket, an old Elmer wisely quipped, “all an antenna tuner does is lie to your radio!” He was absolutely right. This is the inefficiency an antenna tuner is designed to correct.Ī high end manual tuner (STOCK PHOTO) What an antenna tuner won’t do. In extreme cases, the reflected power can damage the transmitter. SWR represents RF power reflected back to its source due to the difference in impedance between the energy source (transmitter) and the antenna. The farther you drift away from that “perfect” resonant 1:1 SWR frequency, the higher your SWR will be. Impedance mismatches between the transmitter and the load (antenna) manifests itself in the form of a high standing wave radio (SWR). Even if you have the “perfect” antenna, it’s not going to be perfect everywhere on all bands. Sounds straightforward, right? Here’s the catch: Impedance varies with frequency. This nomenclature is incorrect, but since it is so commonly (mis)used, it’s become unofficially accepted. By the way, you’ll often see the symbol Ω (ohms) used to express impedance. For nearly all amateur equipment, the load (antenna) must be 50 Z for the transmitter to work properly. The unit is Ohms and the unit symbol is Z. Please don’t pepper me with nit picky comments/emails). Impedance and its cousin reactance are found only in AC circuits (Yes, I know this is oversimplifying things. Without getting too technical, impedance is a form of resistance where there is an opposition to current when voltage is applied. What exactly does an antenna tuner do?Įvery transmitter wants a specific value impedance load on its output. Antenna tuners are a misunderstood piece of hardware, especially in the realm of off grid amateur radio. One way to make an imperfect antenna usable is with an antenna tuner. Maybe you have limited money (or an uncooperative spouse!). Maybe you have to work within municipal ordinances or homeowner association restrictions. Even if you’re not portable, you probably have antenna challenges: Maybe you live in an apartment. When trying to go portable, having a “perfect” antenna is almost impossible. One of the most common compromises is the antenna. Many off grid hams operate portable stations, which presents even more givebacks. We don’t have the same resources as grid-connected hams. A lot of off grid amateur radio involves compromises.
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