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Author Topic: Quick and dirty 434 MHz 8 Element Yagi  (Read 1349 times)

Offline ChrisSmolinski

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Quick and dirty 434 MHz 8 Element Yagi
« on: July 23, 2020, 1829 UTC »
I got hooked on monitoring the various 433.98 MHz devices that occupy most neighborhoods: weather stations, security sensors, and even car tire pressure sensors! So i wanted to make a directional antenna to see if I could both get better reception, as well as determine the direction of some of the transmissions.

Made with pieces of #14 electrical wire for the elements, on a 40" wood strip boom. The driven element is a folded dipole, and fed with a TV 300 to 75 ohm balun and RG-6 coax:



Mounted on a camera tripod:



Radiation pattern, measured using a RF generator located some distance away into a short piece of wire as the signal source, the yagi feeding my AirSpy receiver and rotated in 10 degree steps. Even looks like a real pattern ;D



Designed with my RF Toolbox program for Windows/macOS: https://www.blackcatsystems.com/software/electronics-antenna-design-software.html
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline ThaDood

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Re: Quick and dirty 434 MHz 8 Element Yagi
« Reply #1 on: July 24, 2020, 0644 UTC »
Huh... Like the one that I made in the mid-80's to watch a PBS-TV translator that came in kick-ass in the winter on just a UHF Loop, but was severely attenuated in the Summer foliage. So, I needed something with a lot more gain on UHF TV CH56. And, that worked well. (Hmmmmmmmmmmm... I wonder whatever happened to that beam?) Anyway, how is your match on 432MHz is to hear 432.100MHz SSB and CW Amateur Radio stations and even 432MHz Propagational Beacons? Or, even 435MHz Amateur Satellites?     
I was asked, yet another weird question, of how I would like to be buried, when I finally bite the big one. The answer was actually pretty easy. Face-down, like a certain historical figure in the late 1980's, (I will not mention who, but some of you will get it, and that's enough.) Why??? It would be a burial that will satisfy everyone: (1) My enemies will say that it will show me where to go. (2) On the same point, I can have my enemies kiss my butt. (3) It will temporarily give someone a place to park a bicycle. See??? A WIN / WIN for everyone.

Offline NJQA

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Re: Quick and dirty 434 MHz 8 Element Yagi
« Reply #2 on: July 24, 2020, 1226 UTC »
This reminds me of the “2 meter beam for 2 bucks” in the Nov 1971 issue of Electronics Illustrated.  It was a simple beam using coat hanger wire for elements and a simple coax balun on a wooden mast.  It actually worked and was perfect for a cash poor teenage ham.

You might want to try coat hangers for elements rather than electrical wire.

Offline ChrisSmolinski

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Re: Quick and dirty 434 MHz 8 Element Yagi
« Reply #3 on: July 24, 2020, 1332 UTC »
This reminds me of the “2 meter beam for 2 bucks” in the Nov 1971 issue of Electronics Illustrated.  It was a simple beam using coat hanger wire for elements and a simple coax balun on a wooden mast.  It actually worked and was perfect for a cash poor teenage ham.

You might want to try coat hangers for elements rather than electrical wire.

Yes, I think they'd be more robust for sure. I need to see if we have any wire coat hangers left, most seem to be plastic today.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline Ray Lalleu

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Re: Quick and dirty 434 MHz 8 Element Yagi
« Reply #4 on: July 26, 2020, 1347 UTC »

You might want to try coat hangers for elements rather than electrical wire.

Yes, I think they'd be more robust for sure. I need to see if we have any wire coat hangers left, most seem to be plastic today.
Coat hangers from the dry cleaner! Made from stiff wire.
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