Is the DX Flagpole Antenna Resonant or a non-resonant Antenna?

A. Ham radio enthusiasts generally expect an antenna to have a low SWR. Otherwise, they feel, “It won’t get out well and I might even damage my finals.” What’s your opinion? Is this a universal truth? Here, look at this:

Here the antenna is operated at or near its natural resonant frequency. This is the mode most hams are familiar with. At the operating frequency, the feed impedance is close to 50 Ohms resistive and an antenna analyzer shows a resonant dip. An antenna operating in resonant mode can usually be fed with coax directly, without a matching network.

Here the antenna cannot be fed directly with coax at the operating frequency, for it shows neither an impedance of 50 Ohms nor a low SWR at the feed terminals. Some form of external matching is required for an antenna operating in a non-resonant mode. Frequently it is an antenna tuner. If you are contemplating, for example, a 20-foot, no-radial, OCF DX Flagpole Antenna, take special note... It almost always operates in a non-resonant mode.

Therefore, do not attempt to feed a non-resonant mode antenna directly with coax. Some form of a matching system at the base is a requirement. Have you seen our DX Flagpole Antenna?

Read more about this phenomenon on our RF Blog

Contact Us

Not finding what you're looking for? Contact Us Directly