I cut it twice and it’s still too short!

January 18, 2020

For my satellite ground station I built an antenna from the plans by WA5VJB http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf

I originally built a 7 element 70cm antenna. But then added on a two element 2m one. While I had tuned the 70cm antenna, it was tuned a little too low after the second cut to shorten the driven element. But it passed, just barely.

While attaching the new antenna to the old, I got frustrated smacking the darn thing into everything and hacked off the end, converting it to a 5 element in short order. With years of experience under my belt I have learned that anger is not a great engineering design philosophy.

I didn’t check the tuning before mounting it up here.

img 1653 2

Lets take a look at what the NanoVNA Says. This is the return loss chart for 2 m frequency.

2m cheap yagi return loss

While the tuning is a little low for what I want, it's close enough to work. For example most satellites are around 145 MHz.

70cm cheap yagi return loss

Unfortunately this is awful. I need tuning closer to 435 MHz, this bad boy is coming in at 415 MHz. Looks like it's time to take out the plumbers torch and solder some more wire back onto the antenna :).


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Written by Chris Prosser Data Science Engineer, Maker, Bad Sculpter, located in grey Seattle