snip

hi "jerry"

i want QHA models and i try to adapt them for 2GHZ it's for
heliosynchron
satellite for earth sensing
thank u

Hi "disc"

Wow, thats a small Quad Helix. Tell me the dimensions. I'll try to
model
it for you using EZNEC.
Is this a real project? That is, do you have the antenna, or are you
planning to build one? If you have a "store bought" 2 GHz Quad helix,
there are certainly some patterns available from the mnanufacturer. If
you plan to build the Quad helix, are you able to make any impedance
measurements of the model?
As you know, the fundamental plan in the Quad Helix design is to make
one
loop radiate 90 degrees later than the other due to the impedance
difference between the two loops.

Jerry KD6JDJ

Remember that gigahertz-level quad helixes used on satellites are usually
multiturn devices. Model results for a 137-MHz, half-turn antenna scaled
up to 2 GHz may not be appropriate.

.... Rich W2RG