how to rotate linear polarization in waveguide

[J.C.Maxwell]

Hi everybody.
Im designing a cylindrical waveguide that feeds a horn antenna. operating frequency is about 6 -18 GHz.
I want to rotate the polarization of wave in waveguide and antenna by 45° . could anybody help.

 

[jiripolivka]

There is a particular mode in your waveguide. To "rotate" the mode you must rotate the device exciting that mode. For a wide band like yours it is easier to rotate the coaxial to waveguide transition on the waveguide end against the waveguide section with the horn.
Over a narrow band you can insert a quarter-wave plate in the waveguide and rotate the plate.

 

[J.C.Maxwell]

he first problem is making slant polarization in antenna. how could we receive slant polarization with pyramidal horn?
thanks

 

[Hadi-Alik]

Hi Maxwell,

In fact you two options:
1- To change your antenna to radiate slant polarized wave
2- To polarize the wave emitted by the antenna to be slant polarized.
Well, you dont want to use the 1st, so you can use some kind of polarizer in front of your antenna. There are some designed of multilayer EM polarizers where the output wave's polarization is rotated by 45deg. It can also be very wideband like this:
https://onlinelibrary.wiley.com/doi/10.1002/mop.1237/abstract
I hope this works

Rg
Hadi

 

[J.C.Maxwell]

thanks Hadi.
Using multilayer polarizer is a good idea, but i want to use this horn element in a 18 element linear array. do u think it works in array?

 

[Hadi-Alik]

Basically you can choose both. I guess it would be better to use one polarizer in front of every element. However, If the size of your array is not physically so large (depends on the frequency) , using one polarizer for the whole array would be very interesting (and original).