slant polarized Horn antenna

hi all.
im working on a horn antenna with slant linear polrization in 2-6GHZ and 6-18GHz.
the dimensions of horn antenna are very small. 150*60*50mm. and no more space for larger structure.

what can i do for rotating the polarization.
the power is 200w CW.
gain is about 0-5dBi.

thank you all.

What about rotate the antenna?

Z

no. this is an airborne antenna and rotation the antenna is not proper.