mosfet ring mixer

Hi friends,
I am designing direct conversion receiver with mosfet ring mixer in RFIC
project.
For the reason of high P1db needed, mosfet ring mixer is connected to antenna
directly. Carrier: 900MHz, LO:900MHz.
My confused spots are as following:
1. Does the mixer need perform input matching with antenna? Some paper suggest
no power matching at the input but make load of mixer sense the voltage of
antenna. Is it possible? if power matching, how?

2. If no LNA presents, is the mixer a current switch or a voltage switch. This
problem makes me confused a long time! Becaus the difference induce different
post mixer
operation. for current switch, a I to V converter needed while for voltage, just
connect to VGA and FLT is OK.

Thanks a lot

By the way,
If use MOSFET ring mixer for direct up conversion, how to calculate power
conversion gain, it seems no way to perform power matching in IF end(zero IF

used in my project). Use voltage conversion gain?

Thanks again!
fxxjssc