Dual- Frequency Patch with circular polarization
Dual- Frequency Patch with circular polarization
(OP)
Hi everybody!
I am a little bit new in antenna fabrication. In this moment I am trying to build a new antenna for two different frequencys(868 MHz and 917 Mhz) for some utilities. I was looking for some desgins, but I only have been reached good behaviour in 868 MHz. I have been using a square patch with 4 slots over FR4 dieletric.
Thank you all for your tips!
I am a little bit new in antenna fabrication. In this moment I am trying to build a new antenna for two different frequencys(868 MHz and 917 Mhz) for some utilities. I was looking for some desgins, but I only have been reached good behaviour in 868 MHz. I have been using a square patch with 4 slots over FR4 dieletric.
Thank you all for your tips!
RE: Dual- Frequency Patch with circular polarization
Antenna will be about 6.5" square and spaced off the groundplane by about 2.5" and the location of the two probes will be closer to the outer edge of the patch, with coax. protruding thru the ground plane by around 2" to reduce center conductor inductive losses.
If this is the article you found to put four slots in the patch; http://www.eurojournals.com/ejsr_32_2_06.pdf, I'm certain you don't need any slots for your patch antenna. Those are only to extend the bandwidth much further than you need and are an extra complication in the manufacture.
RE: Dual- Frequency Patch with circular polarization
RE: Dual- Frequency Patch with circular polarization
If you have a hint on what gain or pattern coverage area you need, that'd help the solution.
One other option is a notch antenna with some simple wings to achieve CP over your 5% bandwidth and a gain value between 0 dBi up to +8 dBi could be chosen simply by changing the size of the antenna (little brother vs. big brother). It's something I came up with years but I tried to make it ultra wide band. The notch would protrude outward though, i.e. not be a flat circuit and be about 5"x5"x0.01" size (thickness 0.01 inches not too critical, even one inch thick would work) for zero dBic gain and about one foot square x very thin for +8 dBic gain. That antenna would have 2:1 frequency bandwidth if you need to go from 0.8-2 ghz.
RE: Dual- Frequency Patch with circular polarization
Thank you in advance again!
RE: Dual- Frequency Patch with circular polarization
RE: Dual- Frequency Patch with circular polarization
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RE: Dual- Frequency Patch with circular polarization
I think that's the problem.
RE: Dual- Frequency Patch with circular polarization
A rectangular patch will never do the bandwidth, but will do the circular polarization.
An E-shaped patch, like this:
http://www
might just do the bandwidth, but it will only do one polarization.
You should probably look at some sort of spiral shaped antenna .
www.MaguffinMicrowave.com
Maguffin Microwave wireless design consulting
RE: Dual- Frequency Patch with circular polarization
http://
www.MaguffinMicrowave.com
Maguffin Microwave wireless design consulting
RE: Dual- Frequency Patch with circular polarization
RE: Dual- Frequency Patch with circular polarization
RE: Dual- Frequency Patch with circular polarization
What would you recomend me to do, to achive a Circular Polarized patch antenna, between 870 mhz and 920mhz (It is no necessary to have a bandwith of 50 MHz, only if that works in both frequencies is enough).
My last design is as I mentioned before,a square patch antenna with two probes 90°.
Thank you in advance!
RE: Dual- Frequency Patch with circular polarization
*Higger, I can send you some graphs of my results to explain me better.
Thank you to all!
RE: Dual- Frequency Patch with circular polarization
You have a problem with your 90 degree hybrid most likely. I hope you put a 50 ohm load on the unused fourth port of that 90 degree hybrid, if not your return loss will be bad.
A good 90 degree hybrid, with nothing connected to the ouput, and a good load on the fourth, unused port will get -20 dB rtn loss, so your -7 dB is very odd/something done wrong.