24.15 GHz patch antenna?

[biff44]

Anyone have proven dimensions for a 24.15 GHz patch antenna? Linear polarization. If so, let me know dimensions and material details. Need to make a quick prototype.
Thanks,
Rich

http://www.MaguffinMicrowave.com

Maguffin Microwave wireless design consulting

 

[Higgler]

I'd cut and try it.
Just make it 0.6x 0.1 wavelength in size (that's electrical size, not physical, hence use sqrt of your dielectric constant to shrink the physical size.) The 0.1 wavelength width can be larger which increases your bandwidth.

solder your connector from the bottom exactly in the center of the patch and start trimming copper from one side of the substrate to optimize VSWR which will be at a frequency around 10% lower than your 24.15 ghz number, then trim from both ends of the patch to set your frequency to the 24.15 ghz. The final trimming can be by cutting corners of the copper as opposed to cutting all the way across the strip.

It's a pretty small antenna, so use a microscope to do your trimming, and possibly a dremel tool for the copper removal. If you have to put a protective cover over your final antenna, that's another complication to work out.

I've done this cut and try many times and you easily get excellent results, though I haven't been that high in frequency.

Dielectric tolerances of +/- 1%, and the connector attachment method make it difficult to get a perfect design on the computer on the first try. Usually, you'd make an assortment of dimensions to just hit your frequency target after the computer does it's thing. Even in production, if the dielectric value changes, you'd have a selection of artworks for etching to put you back on frequency once the dielectric value is found.

kch