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What is the purpose non-symmetrical feeding line position in patch antenna?

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Advanced Member level 3
Feb 25, 2012
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There is a patch array where feeding line connected not exactly to the patch center on the wide side. Patch have classical dimensions with W>L, but it's length L is somehow reduced because of non-symmetrical feeding. So L is shorter compared to standard procedures for finding effective patch length. I simulated single patch in sonnet lite and get exact center frequency, but do not know how to interpret current density and did not find any material on patch antennas with offset feeding on the wide side.I have few ideas on non-symmetrical feeding: maybe it gives increased bandwidth, or made for reduced size, or impedance matching, or even for some polarization altering. So the first idea is to compare S11 of classical patch and this patch in sonnet lite, but it is difficult because i did not clarify on how to calculate patch edge impedance without using feeding line, as comparison results depend on quarterwave matching.
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Hi Terminator3,

I assume that you're exciting the fundamental mode (variation in L).

The patch antenna acts as a cavity resonator, and therefore the energy could be input (almost) anywhere in order to excite the desired mode. The position of the feed will only effect input matching and the available modes that can realistically be excited.

The patch width W serves to effect this matching - hence it is usually tuned to optimize bandwidth as well. It seems fairly natural that by moving the feed position, the system can be re-matched by adjusting W. So I imagine you are correct - most likely this is done to optimize some matching condition like bandwidth.

Found a quick example **broken link removed**.
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