Antennas

Antenna Tuners, Impedance Matching, and SWR

Antenna tuners seem to be some of the most misunderstood devices in all of amateur radio. In this article, I’ll try to explain what is happening when you use an antenna tuner. I’ll try not to get too much into mathematics, and I’ll also try to squash a few myths. I really don’t like the […]

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PL-259 Soldering

Do you solder the coaxial shield to the connector body when installing a PL-259 plug? What are those holes really for? I’ve been installing PL-259 plugs onto coaxial cable since I was about 16, and I’ve never soldered the body of the connector to the braid. I’ve not had any problems from not soldering the […]

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Alpha Delta Switch Arc-Plugs

I recently bought a couple of Alpha Delta coaxial switches, and noticed they come with a built-in surge arrester which can be replaced after a surge. They call them “Arc-Plugs”. These are on sale at DX Engineering for $9.99 each. I thought that was a little steep. When the switches arrived, I took at look […]

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WSPR Antenna Comparison

Having recently raised a Off-Center Fed Dipole, and figured out how to use WSPR with my FT-991, I thought it would be interesting to compare the OCFD with my 35′ End Fed Wire. Getting WSJT-X to work with the FT-991 was a bit of a challenge, but I mostly blame the Glenmorangie. Some handy links […]

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Coaxial Cable Length Does Not Change Antenna SWR

I’ve heard this for decades, and I first heard it when I got into CB radio when I was a kid. You’ve gotta to cut your coax to the right length if you want low SWR’s More accurately, if you are driving a mismatched load (e.g: a poorly tuned antenna) it depends where along the […]

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Why 50 ohms?

Coaxial cables, antennas, amplifier inputs and outputs, typically have either a 50 ohm or 75 ohm characteristic impedance. Why? It all comes down to the characteristic impedance value for maximum power transfer being 30 ohms, while the characteristic impedance for theoretical minimum attenuation (loss) is 77.5 ohms. 50 ohms is more or less in the […]

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Antenna Field Regions

Antenna radiation is made up of several different regions. The transitions between these regions are not distinct and changes between them are gradual. The reactive near-field region is the region close to the antenna. In the reactive near-field region, the energy decays very rapidly with distance. The electric fields do not exist alone by themselves […]

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