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# Resonance in microstrip antennas

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#### Asim Ali Khan

##### Junior Member level 3
Salam all
I have a basic question related to the resonance freq in microstrip antennas.Simply wht is it?its significance in strip antennas.Wht does the resonant resistance mean.
pls reffer any related stuff.whuch really help me out.
thx\]

Hi, Asim:

A non-travelling wave antenna depends upon resonance to radiate out the energy. Take a simple patch antenna as an example:

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A==feed line===B C|
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If we look at how the energy goes in the time domain, you will see the following: Energy comes from point A. It hits point B. Some energy bounced back. Some energy goes on. Then, it will hit point C. Slight portion of the energy will radiated out. Most of the energy bounced back. It will travel and go back to point B. Some energy will bounced back from B. Some energy goes on and go back to A. You can see, the energy bounced back and forth between point A and B. Everytime, it bounces back, some small portion of the energy will radiate out. Most of the radiated out energy in fact is stored in the proximity. Only some portion of the energy will be radiated out into the space. For the energy at such a frequency that the distance between B and C is half of the wavelength, the radiated out energy has the same phase and they will become bigger and bigger, while the energy incident from A to B and reflected back from B to A will have the opposite phase from those energy goes back from C to B to A. They will cancel each other. At the resonant frequency, little energy will go back to A while most energy will be radiated out from the bouncing back and forth between A and B. Hope my comments are useful to you. Best regards.

pls refer this paper:

Microstrip antenna technology Carver, K.; Mink, J.; IEEE Transactions on Antennas and Propagation.[legacy, pre - 1988] Volume 29, Issue 1, Page(s):2 - 24, Jan 1981

Regards,

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