<title>New Q-band array SIS receiver with ultrawide band for the Nobeyama 45-m telescope</title>

Abstract

We have an on-going observation project of the Sunyaev- Zel'dovich (S-Z) effect using a 40 - 50 GHz focal-plane array SIS receiver installed in the Nobeyama 45-m telescope in order to measure Hubble constant. The receiver have 6 beams located at 2 X 3 grids of 90' interval and have a typical receiver noise temperature of 40 K. We are improving the array receiver to increase the observing efficiency by reducing of the receiver noise temperature and increasing of the IF bandwidth. The direct connection of IF amplifier and SIS mixer should realize these performances. However, this may introduce impedance mismatch and heat flow from the IF amplifier to the SIS mixer. We tested a SIS mixer with an one-stage HEMT IF amplifier. There was no severe temperature increase in the SIS mixer. The impedance mismatch may make some undulations in the IF output character. The SIS receiver were operated with equivalent performance to the original SIS mixer in LO frequency range of 42.5 to 48.5 GHz and in IF frequency range of 1.1 to 2.5 GHz.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.