monopole antenna isolation increment techniques

hey all

I'm doing a project to enhance the isolation of two wire Monopole antennas. these antennas radiate at 250MHz and 350Mhz respectively and are separated 2 meters by a ground plane. any ideas about what options do I have? I am thinking about Fresnel layers blinding, dpg ground, etc. any comments on these techniques are appreciated as well.

thanks a lot

Just changing the polarization (position in your case) of the two wire antennas would give extra dB's of isolation.

why you dont use the absorber ?