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ghz frequency loop yagis

Feb 9th 2016, 00:53

WD6EJN

Joined: Apr 4th 1998, 00:00
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Some time ago I built several two meter yagi and quad antennas from yagi and quad calculator sites.
Every parameter was there for me to input such as gain diameter of elements and length of boom etc etc.
Why is it so hard to find a loop yagi (look like key rings) calculator for the bands above 70 cm or so?
Feb 9th 2016, 04:15

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
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http://g3jvl.com/programPages/loopQuad.php
Here is a downloadable program. As I recall, he is the first one to come up with a design that worked well--and called it a Loop Quad rather than a loop Yagi, though hams in the USA would call his design a Loop Yagi.

Zack W1VT
Feb 16th 2016, 21:39

WD6EJN

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Thank you for this!
maybe because he is/was british the lengths make less sense to me.
I had to stare at it for almost an hour.
I wish it just had diameter (circumference devided by pi)) rather then making me believe that I have to apply (cf correction factor?) the linear yagi lengths to it.
The old yagi and quad calculators gave director lengths and wire lengths and lengths of one side of the quad or all the way across.
Some time ago I tried to build a quad antenna in my mom's living room as I had to live there too, I couldn't get it to work (as with most of my work) and think it was the wire I used, which was very cheap tin plated copper art wire as I couldn't afford or find copper weld.
This suggest cutting the linear lengths, then with cut & try forming them into loops, it doesn't seem to include the impedance once the loops are shorted at the ends.
This is all I could find in my searches too, at these frequencies there is no room for error, it's too bad there isn't one more category that lists diameter or radius.
Feb 17th 2016, 15:33

W1VT

Joined: Apr 4th 1998, 00:00
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Reproducible Quagi Antennas For 1296 MHz
Author: Overbeck, Wayne, N6NB
http://p1k.arrl.org/pubs_archive/74566
He came up with designs using #18AWG bell wire.
Feb 19th 2016, 17:24

WD6EJN

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Quote by W1VT

http://g3jvl.com/programPages/loopQuad.php
Here is a downloadable program. As I recall, he is the first one to come up with a design that worked well--and called it a Loop Quad rather than a loop Yagi, though hams in the USA would call his design a Loop Yagi.

Zack W1VT



With the exception of a qst article some year back a loop yagi for Wi-Fi made out of key rings!
I notice most of the loop yagis above 1296 are just metal discs.
As one goes higher in frequency loops made from wire become inconvenient.
I wonder if the gain goes up (besides bandwidth) when metal disc are used? capacitance would be an issue and wonder if the disc elements should be mounted perpendicular to each other.
I have seen loop yagis where this was done, this may have been for static collection on a weather station, rather then an antenna.
Also, measurements using my common tape measure and calculator are becoming obsolete, maybe this is why it is so rare to find this information, actually I found inches to be more accurate then metric, as it is easier to estimate the final value, remember measure ten times and cut once!
I also can't find if these are attached (brazed, soldered) to the boom, which would dictate the antenna would not work if the boom went through the center.
Feb 19th 2016, 18:08

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

Typically the gain just becomes a function of boom length after the antenna becomes sufficiently long--you might be able to do something clever for a short antenna, but as you make the antenna longer those gains disappear and everything seems to have the same maximum gain.

https://groups.google.com/forum/#!search/disk$20yagi/rec.radio.amateur.antenna/2n9YSYWqZXA/inyGKo2yDiUJ
Description of how to make a disk Yagi by Gary Coffman

Zack Lau W1VT

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