axial ratio

i use HFSS to simulate the circular polarization microstrip patch antenna, the eRHCP is more 5dB,and eLHCP is about -3dB, but the axial ratio is 3dB. i want to know how to obtain the axial ratio from the eRHCP and eLHCP. and how to judge the circular polarization is good or not?

regards!


cybcad

If your antenna is a RHCP antenna, only when the difference between
the RHCP and LHCP is more than 15dB, Can the axial ratio be lower
than 3dB. But in your case the difference is just 8 dB, I wonder
how the axial ratio is 3 dB. Can you post the plot?

hi stefen:
can the axial ratio be denoted by

r=(|ERHCP+|ELHCP|)/(|ERHCP|-|ELHCP|)

regards
cybcad

With HFSS, when you look at axial ratio, which angles I should take for teta and phi ?

Best regards,
Ludovic

hi Ludovic

in general, we only care about the axial ratio in the direction of main lobe, so you just take the angles for theta and phi in mainlobe direction. if in the main lobe range the axial ratio is good ,it's enough for you.

Hi Cybcad,
thanks a lot for your advice

Can you tell me how to interpret a 3-D Axial Ratio plot and E-theta, E-Phi plots.

thanks

Hi i am simulating a 2.4 GHz circular polarized micostrip antenna on ADS momentum. The axial ratio is only acceptable when theta =90 degree.

Is theta =90 degree or 0 degree the direction of main lobe?

Hi, i wonder how did you calculate axial ratio with this expression: r=(|ERHCP+|ELHCP|)/(|ERHCP|-|ELHCP|). In my example, gain of RHCP is -2.65dB and LHCP 7.6dB. However HFSS shows the axial ratio 5.1dB. I cant find where is the problem, am i considering wrong variables in HFSS?
thanks