Interesting tunable TV antenna

Interesting tunable TV antenna

Interesting tunable TV antenna

One of the engineers found this antenna lying in his garage. We had a quick chat about how it radiates and it turned out to be quite an interesting discussion. Someone said it’s a loop antenna, others said it’s a folded dipole. Another guy said the manufacturers probably didn’t have a clue how the thing works. They just took a bunny ear and told the manufacturers to make it tunable. So I thought lets blog about it and see what you (our readers) think.

The antenna is fed at the base as showed below.

Feed of the tunable TV antenna

Feed of the tunable TV antenna

TV antenna being tuned

TV antenna being tuned

The image above shows how the tuning part pulls in and out which seems like it’s a short circuited transmission line that varies the admittance while changing the resonant length of the antenna. Below is an equivalent circuit diagram of the antenna.

Equivalent circuit diagram.

Equivalent circuit diagram.

Please comment if you think you have a better idea how it works.

Author: Robert Kellerman

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