External GSM antenna
External GSM antenna
(OP)
Hi,
I would like to build a bi-band GSM antenna (900-1800) for external conections, but I can't find homebrew projects on the web. Can someone help?
The antenna can be omnidirrectional or dirrectional, it doesn't matters.
Thanks
I would like to build a bi-band GSM antenna (900-1800) for external conections, but I can't find homebrew projects on the web. Can someone help?
The antenna can be omnidirrectional or dirrectional, it doesn't matters.
Thanks
Thomas K.
http://www.emcrf.eng.br
ICQ#282786426





RE: External GSM antenna
For general dimensions, wavelength is 11.803"/0.9 ghz = 13 inches and hence it's 6.5 inches at 1.8 ghz. To get good VSWR, the funnel spread angle should be approximately 60 to 120 degrees. The smallest dimension of these parts that might work is a funnel that's 5 inches height with a 5 inch diameter pie plate. I recently made a 1-40 Ghz bicone antenna that was 3" tall and 5" diameter, hence you may even get smaller than the 5" dimension noted above. The antenna gain for an omni antenna= 112/(beamwidth in degrees of the elevation pattern). Hence a 13 inch tall funnel should provide 51 degree elevation beamwidth or about 6-8 dB gain. It'll radiate along the horizon well, and null straight up. If you make it very tall, 15+ inches, make sure it's level when mounted.
Kevin.