Evohome HCE80 with 2 HRA80 antennas ?

[jackvanmessel]

Tried to install an Evohome Wireless Manifold Controller HCE80 with Antenna HRA80 in an apartment with concrete walls. Apparently there are steel rods in the walls to reinforce the concrete. This acts as a Faraday cage, limiting the signal to and from the wireless thermostats (DTS92) to almost zero.
Could it be possible to hook 2 HRA80 antenna's (one on each side of the concrete wall) to 1 Manifold Controller HCE80 ?

If not, any other ideas to solve this problem are appreciated.