What is This Antenna?

Paul Zander, AA6PZ

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A friend had what he thought was a UHF TV antenna, but wasn't sure how to connect it.

Near the middle of the antenna are a pair of wing nuts. This is "obviously" where the feedline would connect. There are a pair of heavy wires parallel to the boom, and a short section of 300 Ohm twin lead that looks like it was installed at the factory. There is no direct connection between the "feed assembly" and any of the elements. I modeled the antenna with EZNEC. Not surprisingly, it did not work.

As an experiment, I changed the model to make element 7, counting from the left as 1, the driven element. This resulted in a model of a Yagi antenna with approximately 10 dBi gain from 440 to 500 MHz. The antenna is several years old, when UHF TV covered 470 to 800 MHz, this antenna was not intended for TV usage.

So what was the original purpose of this antenna?  What is missing to make a connection between the feedline and the elements?

The answer came from Bob, K8YS in Cincinatti.
He recalled that around 1980 there was a "pay to view" TV service.  They broadcast on a UHF TV channel, but "scrambled" the signal.  They sold a package with the decoder box and a small antenna. 

After receiving his email, I recalled that in the San Francisco area, there was a similar service.  And it used a channel that matches the frequency coverage of this antenna. Two sets of terminals would make it easy to connect in with the roof-top antennas that most people used at that time before cable.

In both Cincinnati and Silicon Valley, there were so many electronics companies that home-brew decoders were widely made and distributed to friends and neighbors.  The "service" only lasted a few years.