cross polar in momentum
in ads momentum , when i view 2D radiattion pattern , it give me
1-graph of linear polarization that contain E_cross and E_co
2-graph of circular polarization ,
is that the patch antenna produces two polarization in the same time?
and what there is the E_cross?
thank
Salaam Abu Maria
the term co and cross polarizations are used because of certain reasons.
co polarization is the polarization of interest,like for instance a linearly polarized antenna is not completely(100%) horizontal or vertically polarized.so cross polarization is used to define the exact polarization of the antenna.
For instance your antenna is supposed to horizontally polarized.E-co would be the polarization in refernce(horizontal) and E-cross would be (vertical).The cross polarization may be specified for an antenna as a power level in negative dB, indicating how many decibels below the desired polarization's power level the x-pol power level is.
If the polarization is Right Hand Circularly Polarized (RHCP), the cross-polarization is Left Hand Circularly Polarized (LHCP).
Hope thats helpful
Regards
thank u chachitoelflaquito
it helped me...
but I have some questions if you want:
1/-what is the physical cause of this cross-polarization
2/-in ADS/MOMENTUM simulation , when I want to see the radiation pattern in 2-D , MOMNENTUM give me "A-graph of linear polarization with (E and Eco-Cross)in the same graph as a function of theta for example
B-graph of circulair polarization with (E_left and E_right).
then: is that the antenna supports two types of polar ?
and in the case of circular polar , it give me : that E_left and E_right are the same!
please answers all the questions , i like understand
thank u
Salaam Abu maria
Like i said in the previous response cross polarization is a measure of amount of deviation from the co-polarization measured in dB's. its because you dont get exactly RHCP or LHCP 100 percent of the time,the polarization that we get out of the antenna is a combination of both,co -polarization refers to your desired polarization from the antenna and cross the unwanted polarization that antenna is producing which is the counter of your desired polarization.
E-Left and E-right mean here LHCP(left hand circular polarization) and RHCP(Right Hand Circular polarization). like i said an antenna rarely has 100% RHCP or LHCP. so to have a understanding How good you have a polarization we tend to measure both the polarizations in order to see the performance of the antenna.
Hope that is helpful
Regards
thank you very much chachitoelflaquito
then you say" ...so to have a understanding How good you have a polarization we tend to measure both the polarizations in order to see the performance of the antenna"
So that's the reason why momentum gives the two graphs of polarization...?
also please
2-what it means E_left is similar to E_right?
NB:it's my turn to give you something , we say salam aaleykoum , not salaaam only !
sorry very sorry
chachito...
What do you think of this sentence"...However, with linear polarized antennas, it is sometimes more convenient to decompose the far-fields into (Eco, Ecross) which is a decomposition based on an antenna measurement set-up. For circular polarized antennas, a decomposition into left and right hand polarized field components (Elhp, Erhp) is most appropriate..."(refrence : the help of momentum/ads)
he say in linear polarized , and after he speaks of the circular polarization , I understand my that cross-polarization is that in the case of linear polarization
Wa Alaykum As salaam abu maria.
E-left means E-LHP and E-right means E-rhp. hope thats clear.so normall speaking E-co is the desired polarization and E-cross is the polarization thats part of the actual polarization which is undesired. if you are designing an antenna For RHCP. then E-co is RHCP and E-cross is LHCP.
Hope thats clear.
NB:: You never replied back to the salam in the first place .
Regards
CHachitoEL
wa aaleykoum as salam wa rahmat'ou rabi
its very very clear,but what do you think for this:(reference :the help for software momentum /ads
E(far field)=E_co+E_cross=E_theta+E_phi=E_lhp+E_rhp (*)
so for this equation we that we have choice to decompose E_far field betwee this 3 methods , so that confirm that decompose E far field in co and cross is in the case of linear polarisation only because you see that in the equation, it makes the difference.because if for exemple : E_rhp is the desired polar then it is the co , and the E_lhp is the cross , then it makes no sense to repeat it in the equation(*).
sorry ,is corrected to the top(thank u) very much freind