Narrowband shorting at output of up-converting transistor mixer

Hi!

I am designing a freqency mixer and have a bit of a problem. It is a single-ended multiplier-type up-converter FET mixer, so the LO is applied to the gate while both the RF and IF signals are applied to the drain. In all the literature I read that I should short the LO and its harmonics on the drain: however, my LO signal is 2GHz and the wanted RF signal is 2.1GHz. The RF bandpass filter in my diplexer shows an open-circuit at the LO frequency and I cannot think of a method which would short the LO but not the RF which is close in frequency. Can anyone help me with an idea please?
Or is it unnecessary? I could just calculate with a 50ohm termination of the RF at the gate of the FET (being close to the LO and no filtering there) and an open-circuit at the drain at the LO frequency, and using these and the S-parameters I could adjust the impedance matching circuits accordingly.

Thanks in advance for any help!

you need some sort of balun or transformer and two fets so that the LO power is vectorially canceled.

You COULD try a very narrow band filter, but you will need a very high Q resonator (i.e. big lumped elements or transmission lines)