Optimizing Cx Polarization Pattern for Patch Antennas

[DenVo]

Dear All,

does anybody know ways to increase the cross polarization supression of a single microstrip patch antenna?

The following technics are known:

1. Feeding the patch with two feeds. One feed has 180° phaseshift.
2. Bending the corner of the patch.

Regards DenVo

 

[Higgler]

feeding the patch with four feeds helps. That'll give optimum if you build it nice and symettrically.
How much isolation do you need? Who picked a patch? I assume it's mechanically constrained.
Crossed notched antenna can get 40 dB over 3:1 bandwidth.
We get 50-70 dB regularly (tunable to 80 dB I would surmise) with a dual pole horn across more than 2:1 bandwidth.

 

[DenVo]

Hi Higgler,

how would you feed the patch with 4 feeds for one polarization? At present I use 2 feeds (180° out of phase)for the V-polarization, like that:

________________
- 0 -
- -
- -
- -
- -
_______0_________


0= Feeds

Regards DenVo

 

[DenVo]

________________
_______0________
________________
________________
________________
_______0_________

 

[Higgler]

Use a feed pair North South with 180 hybrid splitter, same for east west. It keeps the current along a straighter trajectory on the patch and optimizes isolation. Why use presently two feeds 180 out of phase when you can get similar for zero degree splitter and rotate the patch 90 degrees?