How to improve radio signal in RNS510 on polo

[Lieto]

Greetings.

I recently had RNS510 installed in my polo and noticed that my radio FM signal became worse then in my old alpine system. I asked guys who installed RNS and they said that there are 2 antenna inputs in RNS and only one output in polo (something along these lines).

Got guys who are quite skilled at electronics but they never saw RNS and dont know how to help it.
Is there actually a way to help it? Install 2nd antenna or something?
I love listening to FM radio and now it's sound is kinda noisy even in city center (which never happened before).
I mean its not VERY noisy, just not really perfect and clear like it was with my old alpine cda117 unit and since i live in capital and drive in city center i think there is no real reason for it not to be perfect. Any $15 radio receiver gives you rather perfect sound signal there limited by its dynamics quality.
What should i buy and install in order to help it?

Thanks a lot.

p.s. and ye, i know that cda117 is considered better sound then RNS, it just looked silly and i wanted navigation unit -)

[mikinoz]

RNS is dual fakra antenna. The Polo is single antenna.

You need a single fakra male to dual fakra female cable so both inputs on the RNS have signal.

[Lieto]

Good to know that i can fix it -)
Any wide known / native adapter that you can point me to or should i just visit some sort of radio market?