News 08/11
Dichroic Mirror for Separation of
Ka-Tx and Ka-Rx Frequencies

MIRAD has designed, manufactured and tested dichroic mirrors for ESA's Deep Space Antennas. The 35m Deep Space Antenna 2 (DSA2) can now be upgraded to transmit in Ka-band.

The dichroic mirror M7b has to separate the Ka transmit (Ka-Tx) and the Ka receive (Ka-Rx) bands. Receive signals are reflected by the mirror. Transmit signals are transmitted through the mirror via a huge number of holes acting as waveguide parts.

Fig. 1 is showing the Ka-transmit and Ka-receive paths through M7b.



Fig. 1: M7b and Ka Feeds



Fig. 2: Dual Plate Arrangement for M7b


M7b is a flat, dichroic double plate with an elliptical shape. In order to reduce the manufacturing costs, the active dichroic area shall be as small as possible. A section of M7b is shown in Fig. 2.

Frequency ranges:
Ka-Rx: 31.80 to 32.30 GHz
Ka-Tx: 34.20 to 34.70 GHz
Ohmic insertion loss: -0.1 dB

The dual plate arrangement finally consisted of a total of 9550 holes for each plate.

In case of further interest please contact Werner Frischknecht.