Custom UHF Yagi antenna build

[Averagesupernova]

Can't have it both ways. A resistive pad will match the impedance at the cost of insertion loss. This may not matter depending on the circumstances. If you are evaluating the performance of one antenna vs another, etc, then just realize that you are burning up power in the matching pad. If you are after maximum sensitivity for receiving weak signals then you will not want to use anything resistive.

 

[Tom.G]

Another option for the antenna is an amplified antenna. (USD$ 50 - 100 here)

A friend has one and gets over 100 stations -- which is pretty good with the TV and antenna in the basement, 30 to 40 miles from the transmitters, and a large hill in the way!

The antenna inself is enclosed in a plastic case roughly 1 foot (30 cm) square and 1 inch (2.5cm) thick. The amplifier is in a small box that connects to the TV.

Last week, during the Solar Storms, he had poor reception and asked for help when getting only 16 stations.

No joy.

The following day he told me he got it working again! He had changed which power outlet the antenna was plugged in to. Originally it was plugged into a 15 foot (5M) extension cord from a distant outlet, and he had plugged it into the same outlet as the TV.

He went back to using the extension cord and all the stations came back.

UHF radio is Weird! (and probably no RF filtering on the power cord)

Cheers,
Tom

p.s. maybe you could get a powered antenna and use the amplifier for your Yagi.

 

[Guineafowl]

Thanks - yes, the Yagi will get a standard amp like this:

I’d like to get a reasonable signal BEFORE amplification, so the next stage, I think, is to use the VNA to optimise the antenna/balun., assuming I’m aiming for 75 ohm impedance at the centre frequency. Should I just hook them together, ignoring the 50-75 ohm conflict, and show you the Smith chart/SWR data?

 

[Averagesupernova]

Since you have a VNA and are interested in getting a proper match, you should have a look at some YouTube videos about using a VNA. I have seen at least one that explains how to very very easily build LC matching networks with the aid of a VNA. Now be prepared for more difficulty at UHF frequencies compared to lower. Start out matching something in the HF band to get your feet wet. You could possibly build something like this on a couple of connectors.