Final Year Project: Dual-Frequency Microstrip Patch Antenna

Dear all, anyone of you antenna gurus here could shed some light on how to design a dual frequency microstrip patch antenna? The frequency range is above 10GHz, preferably 10GHz and 12GHz. Does this design involve any mathematical analysis? and are there any softwares that I can use for design? I'm using FR4 substrate btw... Thanx a lot :)

hello

using fr4 at these frequencies is not a good idea, the substrate is way too lossy. the result will be an antenna with very low efficiency, the bandwidth will increase though :D . It is better to use ro4003 or another microwave substrate. Could you give some more design specs like polarization, bandwidth...

best regards

Hi there! Either linear or circular would be just fine and for the bandwidth, I was thinking something like around 200MHz for each frequency...Don't know if this is of much help though, I **** at microstrips :P but thanx a lot! and one more thing, is there any mathematical approaches used in designing dual frequency microstrip antennas like these or are they purely trial & error/experimental? :?

hello

it's a lot easier to design small band antennas than broadband antennas. 200 MHz at 10 GHz would be 2 % bandwidth, that's small band. dual band structures are usually built by exciting 2 modes. the natural modes are usually at f0, 2*f0... but the higher mode can be shifted by using slots and/or shorts. the frequency ratio 10 GHz vs. 12 GHz is only 1.2. that's pretty close to 1. a single broadband structure may be easier, but without the FR4 then. there are a lot of dual band structures available in the literature.

best regards

Icic.. any recommended literature on this though? cos there are not many variations on microstrip references here in my library and most of the time I need to search elsewhere I was fiddling around with ADS the other day and experimented with some weird antenna designs and a few of them gave pretty good S11 response but the problem with some of them are their simulated radiation patterns.. There's a particular one shaped like a nazi logo with an off-center feed point which produces a nice 10GHz and 12GHz response but the radiation pattern at 10GHz has a little weird dimple on the side of the hemisphere...I was wondering if this could be remedied? the radiation at 12GHz looks fine though... Regards

any decent book about microstrip antennas should give a few examples
more specific books are:
broadband microstrip antennas, Girish Kumar et al., artech house
Compact and Broadband Microstrip Antennas, Kin-lu Wong, Wiley

best regards

Thanx kleine, i'll try out the books you've mentioned... regards ;)