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What is the impedance of an end fed half wave antenna?
The popular End-Fed Half-Wave (EFHW) Antenna is an easily portable, high-impedance (2,000-4,000 ohm) wire antenna that resonates on its fundamental frequency and all harmonics above.
What is an unun for antennas?
An unun is an impedance transformer, usually 4:1 or 9:1 , which matches an unbalanced antenna to a feedline. A 9:1 transformer is often used for an end-fed half wave antenna.
Do I need a 9 : 1 Unun for a half-wave end fed?
But there is a question: If I install my tuner close to antenna end, can i just plug it into the autotuner or should I connect a 9:1 UNUN first? An end fed, 1/2 wavelength antenna will have a relatively high impedance of 5k ohms or more.
What’s the difference between half wave and end fed wire?
Before I get into the nitty-gritty details, let me first make a distinction between end-fed half-wave antennas, such as the ones sold by LNR Precision and end-fed wires that use some kind of tuning to achieve a 50 Ω output impedance. End-fed, half-wave antennas (EFHWs) are a half-wavelength long and are resonant antennas on the band of interest.
Do you need a 49 : 1 transformer for a half wave end fed?
Half wave end-fed has appr. 5k impedance, you need a 49:1 transformer to match 50Ohms cable. As the impedance of the antenna is very high a small counterpoise of only 1/10 of a wavelenght does the trick. Do use some form of coax-choke at the antenna-end of your coax to stop RF current flowing in the coax-outside.
What kind of antenna is a half wave?
End-fed, half-wave antennas (EFHWs) are a half-wavelength long and are resonant antennas on the band of interest. They use some kind of matching network to trasnsform the very high impedance at the end of a half-wave wire to about 50 Ω. Generally, they are not usable on bands for which they are not a half wavelength long.