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2.4GHz antenna design

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NiHaoMike:
I'm designing a high gain (~18dBi or so) 2.4GHz antenna for use with 802.11 hardware. I decided on a Yagi design as I wanted something that takes up little space in a bag. Instead of wire elements extending out of a stick like a TV antenna, I'm thinking of taking a wooden (or plastic?) board, cutting grooves in it, and pressing copper wire into the grooves. Are the calculations different if I were to embed the elements in wood? Dry wood is an insulator but its dielectric constant is much different from that of air.

As of current, my 25 element design is going to be on a board that is 3' long and 3" wide. I'm thinking of cutting it in half and adding a hinge so it folds to a more reasonable 1.5' length for carrying. Am I correct that I'll need a hinge or other mechanism made of a nonconductive material to avoid affecting antenna performance?

I'm going to use homemade Litz wire to increase the efficiency, so they'll be even more fragile than solid wire.

kaptain_zero:
Argh... My antenna theory is rusty at best, but do you really need 18db gain? The reason I ask is that a collapsible corner reflector antenna would meet the compact, folding and easy to make feature, but only about 12db gain to the front and 20db rejection to the rear.

The most efficient design when you get up in the 2.4ghz and up range is a small parabolic dish..... Easy to get lots of gain with not much material and fairly compact.

Your wooden/plastic idea could be made to work, but at those frequencies... relative humidity would become an issue and might create tuning headaches.

I'd let my fingers do the walking in google, there's plenty of Ham Radio references on antenna design in the 2.4ghz range and up.... Phase 3D (a large elliptical orbit satellite built by hams) had a 2.4ghz down link and decent gain was important to hear that satellite so there was lots of home brew antennas cobbled together for that. I dropped out of the amateur satellite arena about 10 years ago.... so I'm not up on the latest. Amsat.org might have some useful information as well.

Regards

Christian

Psi:
Most people tend to avoid RF design at frequencies that high, you can do the math and build the antenna/circuit but without very expensive test equipment it's hard to tune and fix issues. It requires a ridiculous amount of trial and error. You might be better off finding a forum that deals entirely in RF design to get a good answer to that question.


There's probably only a small handful of people on here with excellent RF knowledge at frequencies that high.

Zero999:
The easiest way to design a 2.4GHz antenna is to etch it on a PCB.

kaptain_zero:
Did some slight poking around on the net, found this site...... http://www.wlan.org.uk/diy-ant.html

Plenty of ideas and information on this topic....

Regards

Christian

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