This is an antenna with an unfamiliar name for me………
I wondered if it was named after the callsign of a ham radio operator who invented it, like HB9CV, F9FT, and W3DZZ. It turns out it’s an abbreviation for QuadriFilar Helicoid, which stands for four-wire helical. Nagara Electronics manufactures and sells it.
I was searching the Internet for an antenna that would cover the entire sky with a single antenna, and I came across this. And it’s circularly polarized. I knew that “isotropic → can fly anywhere → doesn’t actually fly anywhere very well,” but the shape looks like a barber’s sign stand, and it looked funny, so I made one myself.
It seems to be quite popular overseas, because there is a helpful website that will print out not only the instructions for making it, but even the hole pattern if you enter the materials you will use. http://www.jcoppens.com/ant/qfh/calc.en.php
I made it with HIVP-13 and aluminum pipe. Usually I use a pipe bender to bend the aluminum pipe neatly to a 90° rounded corner, but this antenna has to be gently bent into a spiral shape, so I heated it over a gas stove.
Then, place it on a cylindrical ruler and shape it into the desired spiral shape. This is a humidifier.
Assemble them, make a Spertopf(bazooka) balun with coaxial cable and supply power. This time I made one for 145MHz.
The power supply section is completed by inserting a copper pipe one size smaller and “crimping” it.
But as I expected, it was a bit dull… and it ended up being shelved without any real communication results. (Hmm, if I buy this, it’ll cost 16,000 yen…But it’s still bulky…)
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