How to use a transformer to my power amplifer?

I have designed a microstrip line transformer for differential power amplifier.

But I don't know how to use this transfomer.

Ideal transformer can transform the impedance using the turn ratio.

So 1:2 transformer can make 12.5 ohm. I just designed my 1:1 transformer

using microstrip line to see how it works.

Question:
In sparameter, I think there are imaginary part because coupling constant is low.
so I connected capacitor parallely to resonate out but I just see a high impedance.
I cannot see a impedance of variance of secondary attached impedance? If I connect 50 ohm to secondary I can see 60 Ohm. And then If
I connect 10 Ohm to secondary I still see a 55Ohm at the primary winding.
Why I cannot see a secondary impedance at a primary part?