2SB and balanced receiver architectures using hole couplers

The ALMA telescope has now entered cycle 4 operations [1] and as part of a research study proposal [2], we are exploring possible improvements to the ALMA Band 3 receiver cartridge. The Band 3 receiver is capable of detecting both linear polarisations which are discriminated using a waveguide orthomode transducer (OMT). Within each polarisation, both the upper and lower sidebands are separated out using a sideband-separating (2SB) layout. We report on the progress of two new prototype designs that use an integrated OMT with hole couplers to give: (1) a dual-linear sideband-separating architecture, and, (2) a balanced, sideband-separating architecture.