Antennas for bolometric focal plane

The future Cosmic Microwave Background (CMB) experiments will require large focal planes with hundreds of bolometric receivers. For CMB detectors, the field of view should be restricted, as even with cryostat cooled liquid helium temperatures a significant deteriorating performance load will be present (Appl. Opt. 41 (2002) 6543). We present a planar antenna for millimeter band produced by lithographical methods only, which, without lens concentrator or a horn, has convenient beamwidth about F/3–F/4. The radiation and impedance characteristics of the antenna were obtained from a moment-method calculation. The measured beammap of the antenna prototype is presented in this paper.