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ted · 08-31-2002

Hi, and welcome!

I feel good seeing one with long history of antenna construction! I am myself relatively new here, and I have never been a ham. However, I have had interest in antennas for most of my life, and 2.4GHz has some interesting challences: Wavelength is a bit short/ frequency high to make it trivial to make direct downscalng of many constructs good for RF-VHF. Maybe the antennas like yagi are pretty neat and easy to make, but the matching of feed is more tricky due to tiny dimensions and thus greater accuracy needed. And all the secondary phenomens have bigger impact.

Because you have been on 10GHz you know the "other end" where "real microwaves" exist. I have myself seen and also somewhat tried simple microwave antennas for WiFi -- for example built a waveguide "cantenna" and plan soon to test bi-quad (which is, of course, actually also a typical VHF/UHF construction). But for travelling use, I have been thinking of tiny yagi, which may have easily quite impressive gain, and which would pack flat in a suitcase. Much neater and with better form-factor than a waveguide antenna, or a bi-quad or a dipole array. It would be also be possible to explain to (and be innocent enough for) airport security (no place to hide explosives there). But matching to 50 ohm coax needs a balun, and without instruments it would be hard to verify and tune. So I have not strated the project yet. What is your opinion about the matching issue?

08-31-2002	#2 (permalink)
ted Stumbling on Join Date: Aug 2002 Location: Houston,TX Posts: 47	Hi, and welcome! I feel good seeing one with long history of antenna construction! I am myself relatively new here, and I have never been a ham. However, I have had interest in antennas for most of my life, and 2.4GHz has some interesting challences: Wavelength is a bit short/ frequency high to make it trivial to make direct downscalng of many constructs good for RF-VHF. Maybe the antennas like yagi are pretty neat and easy to make, but the matching of feed is more tricky due to tiny dimensions and thus greater accuracy needed. And all the secondary phenomens have bigger impact. Because you have been on 10GHz you know the "other end" where "real microwaves" exist. I have myself seen and also somewhat tried simple microwave antennas for WiFi -- for example built a waveguide "cantenna" and plan soon to test bi-quad (which is, of course, actually also a typical VHF/UHF construction). But for travelling use, I have been thinking of tiny yagi, which may have easily quite impressive gain, and which would pack flat in a suitcase. Much neater and with better form-factor than a waveguide antenna, or a bi-quad or a dipole array. It would be also be possible to explain to (and be innocent enough for) airport security (no place to hide explosives there). But matching to 50 ohm coax needs a balun, and without instruments it would be hard to verify and tune. So I have not strated the project yet. What is your opinion about the matching issue? Last edited by ted : 08-31-2002 at 10:22 AM.