Design of polarizer with RHCP and LHCP (60GHz)

[kaaakTus]

Hi, everyone!!!
I want to design polarizer with two polarizations (right and left circular)
Frequency about 60 GHz
Axial ratio less than 0.7 dB
Have you any ideas?
Thank you

 

[jiripolivka]

Hi, everyone!!!
I want to design polarizer with two polarizations (right and left circular)
Frequency about 60 GHz
Axial ratio less than 0.7 dB
Have you any ideas?
Thank you

Use a quarter-wave plate. Send your linearly-polarized wave through a circular waveguide, and insert a thin Teflon plate into the tube 45 degrees from E or H. Plate length should be quarter-wve long but it usually works with a longer length. L and R circular you set by using + or - 45 deg.

 

[kaaakTus]

Thanks for your answer, I thought about that. But I don't like that switching from RHCP to LHCP and vice versa is mecanical in this design of polarizer. And if the plane will be in E- or H-plane, wave is linear polarization, isn't it?

 

[ferdows]

i think its better for you to design X-pol antenna

 

[kaaakTus]

i think its better for you to design X-pol antenna

Do you think so? That will be feed of the dish antenna
And I don't know about X-pol antenna anything, unfortunately. Have you references?
Thanks

 

[kaaakTus]

I found some information about X-pol already

 

[ferdows]

if u want to use as a reflector feeder so it better u design antenna with linear polarization an u rotate it 45 and it will became slant or x pol but you should notice that your feeder should have equal HPBW in phi and theta direction

 

[jiripolivka]

Thanks for your answer, I thought about that. But I don't like that switching from RHCP to LHCP and vice versa is mecanical in this design of polarizer. And if the plane will be in E- or H-plane, wave is linear polarization, isn't it?

Yes, but this mechanical setting is working well with a minimum effort. There are more sophisticated methods but at 60 GHz they will be complex, lossy and expensive.
You can look into 11 GHz satellite LNBs how it is done there; designing such electronic polarizers at 60 GHz will be pretty difficult.

 

[ferdows]

but at this frequency easy to design x-pol antenna with out rotation and with lens u can shape your pattern

 

[kaaakTus]

OK, thank you!
I need to think about these ideas))

 

[dot4]

Septum polarizer is also an option. But you need to have two feeds, one for LHCP and one for RHCP

 

[kaaakTus]

I think, septum will be very small for this frequency. Very hard to manufacture it. I'm wrong?

 

[dot4]

Yes, but it depends on your manufacturing precision. At this frequency even small geometry tolerances would make a considerable difference in performance.