groundhog1
Electrical
- May 4, 2003
- 43
Hello,
I am trying to make a standard almost square patch with probe feed, where the feed is kind of along the diagonal of the patch.
To simulate/measure axial ratio, I put in a very small pickup dipole element with impedance of 377 some distance from the antenna under test (AUT) face. Then I rotate the antenna under test and watch the S21 between the AUT and pickup.
How come when I rotate the AUT, I don't get the same S21 levels? Shouldn't it stay somewhat constant? I get some really unbelievable variations.
If I rotate the DUT 0, 90, 180, etc. I get very little variation. But on a 45 degree increments, I can get 30dB differences.
I've tried moving the feed all around without making a dent in this problem.
What am I doing wrong?
groundhog
I am trying to make a standard almost square patch with probe feed, where the feed is kind of along the diagonal of the patch.
To simulate/measure axial ratio, I put in a very small pickup dipole element with impedance of 377 some distance from the antenna under test (AUT) face. Then I rotate the antenna under test and watch the S21 between the AUT and pickup.
How come when I rotate the AUT, I don't get the same S21 levels? Shouldn't it stay somewhat constant? I get some really unbelievable variations.
If I rotate the DUT 0, 90, 180, etc. I get very little variation. But on a 45 degree increments, I can get 30dB differences.
I've tried moving the feed all around without making a dent in this problem.
What am I doing wrong?
groundhog