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# circularly polarized microstrip antenna

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#### ardique

##### Junior Member level 2
circular polarized microstrip

hi all,
here i need some help to identified the circularly polarized for microstrip antenna.
how can i show that my design is a circularly polarized? i've search in internet n book but still confius bout circularly polarized. my antenna design is circular patch microstrip antenna at 2.4GHz. i've done my design simulation by using CST microwave studio. can any body help me up to show that my design is a circularly polarized from the simulation result?
thanks

#### tyassin

how to chek the circular polarization of antenna

Hi

You can plot the Left Hand Circular Polar (LHCP) gain and Right Hand Circular Polar (RHCP) gain in CST. If one of them is over 10-15 dB higher than the other you have that polarization. If they are the same, then it is linear polarized.

Regards

phan_9999

### phan_9999

Points: 2

#### ardique

##### Junior Member level 2
hi,
thanks tyassin for your info. here i've attach the 3d of RHCP of my design. can u help me to ensure that this is a circularly polarized. sorry that i didn't attach the LHCP coz my design is for RHCP. can u help me?

phan_9999

### phan_9999

Points: 2

#### tyassin

Hi

I cannot tell from this plot. If you can plot the LHCP and RHCP in the same rectangular plot, then it is much easier.

Points: 2

### barkath

Points: 2

#### balaguru thavamani

##### Full Member level 5
Axial Ratio will give the purity of Circular Polarization.
So with the help of axial ratio plot we can get an idea whether it is circularly polarised or not?
Ideal axial ratio plot will be within 1 dB but in pratical case up to 3 dB is accepted.

regards,
balaguru.

twinklee

### twinklee

Points: 2

#### ping-pong

##### Member level 2
balaguru thavamani said:
Axial Ratio will give the purity of Circular Polarization.
So with the help of axial ratio plot we can get an idea whether it is circularly polarised or not?
Ideal axial ratio plot will be within 1 dB but in pratical case up to 3 dB is accepted.

regards,
balaguru.

Couldnt it be 0 dB for an ideal case and do you think in practical cases upto 3 dB of axial ratio is accepted for CP.

#### balaguru thavamani

##### Full Member level 5
Sorry guys for ideal case its 0 dB
and practical upto 3dB is accepted.

#### suced

##### Newbie level 4
balaguru thavamani said:
Sorry guys for ideal case its 0 dB
and practical upto 3dB is accepted.

applies to every circular polarized antenna?

To check circular polarization in CST, i have to put 2 modes in waveguide port..after the simulation i combine results and i only see if is circular polarized in the farfield combined result? or simulating with only 1 mode, i can see if is circular polarized or not?

I´m bit confused, since the manual dont have much information about polarizations

thanks.

#### Azulykit

Look up this book:

Stutzman, Polarization in Electromagnetic Systems, Artech House, Inc., 1993.

It will explain what you need to understand about the various polarizations.

#### suced

##### Newbie level 4
Azulykit said:
Look up this book:

Stutzman, Polarization in Electromagnetic Systems, Artech House, Inc., 1993.

It will explain what you need to understand about the various polarizations.

From the reviews that i read, it looks like the perfect book for my needs...but unfortunately sending from US+ship+custom taxes.....

Do you recommend another book about polarizations?

#### Azulykit

I guess you will have to decide what you can afford. That is the hard part in engineering.

Good.
Fast.
Cheap.

Pick any two.

#### balaguru thavamani

##### Full Member level 5
suced said:
balaguru thavamani said:
Sorry guys for ideal case its 0 dB
and practical upto 3dB is accepted.

applies to every circular polarized antenna?

To check circular polarization in CST, i have to put 2 modes in waveguide port..after the simulation i combine results and i only see if is circular polarized in the farfield combined result? or simulating with only 1 mode, i can see if is circular polarized or not?

I´m bit confused, since the manual dont have much information about polarizations

thanks.

It depends upon the application usually for base station its accepted.
I'm not aware of CST

#### ardique

##### Junior Member level 2
hi..
here i've attach the 3D view of RHCP and LHCP for my antenna..hope anybody can help me to explain how to obtain this antenna is circularly polarized.. or need to view from other dimension to obtain it? regarding to axial ratio, may i know how to obtain it?

#### ardique

##### Junior Member level 2
what i try know is how to prove that my antenna design is a circularly polarized microstrip antenna. another one is, how the gain effect the antenna design? i means what should i explain if my antenna design is only have gain(abs) is 2.431dB and gain(theta) is 2.360dB. while for square patch have tha gain(abs) is 6.341dB and gain(theta) is 5.932dB. based on theory does the antenna have very high gain is more better? since i need to do comparison between square patch with circular patch. any suggestion?

#### mo33x

##### Newbie level 2
ardique : hey can you give me the design of your antenna . and which version of cst have you used ??

ardique: kindly upload the simulationg file . which version of cst you have used ??

#### Abhishekabs

Hi ardique,
Can you attach RGCP & LHCP plots in rectangular co-ordinated?
Theta vs Gain for LHCP & RHCP for some Phi 0 or 90 deg.

Looks like RHCP, but not sure.

https://www.jatit.org/volumes/research-papers/Vol4No6/10Vol4No6.pdf

You will also see graph of axial ratio,
I guess, that is what balguru was trying to say.

Koglu

### Koglu

Points: 2

##### Newbie level 5
i have problem to make circular polarized microstrip antenna for 145MHz and 435 MHz frequency,, it is independent antenna,, not dual-band antenna,, i hope any poeple help my problem,, and then i request for tutorial for manual design microstrip antenna in CST,, thanks,,

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