how to give coax feed to quadrifilar helical antenna?

i am doing a project on quadrifilar helical antenna.it doesn't have a ground plane.it needs a coax feed.but i don't know how to give coax feed.would anyone giv me help in giving coax feed to quadrifilar

thanks

Use a quarter-wavelength balun. Take a look at the attached document

i am giving coaxial feed using this balun.but i don't know how to simulate this in ansoft hfss.would you plz giv me a helping hand

Hi,

Have you tried using a wave port? If you need to use the wave port internally, you can add a copper cylinder to the back of the wave port.

I hope this helps.
Joline