Design of a Dual Polarization SIS Sideband Separating Receiver Based on Waveguide OMT for the 275-370 GHz Frequency Band

Mamoru Kamikura, Yu Tomimura, Yutaro Sekímoto +8 more

Chao-Te Li, Kuan‐Yu Liu, Wei-Chun Lu +6 more

A heterodyne receiver incorporating superconductor-insulator-superconductor (SIS) mixers has been designed to cover the frequency range from 400 to 520 GHz of the Submillimeter Array (SMA). Various tuning circuits have been employed to resonate out the geometric capacitance of the junction and provide impedance matching to the waveguide probe. Our measurements indicated that a receiver noise temperature of around 90 K, with the contributions from the input noise and intermediate frequency (IF) noise estimated to be around 60 K and 10 K, respectively. SIS mixers integrated with planar orthomode transducers (OMT) have also been designed at 345 GHz for dual polarization detections, and results from the 3-dimensional (3-D) electromagnetic (EM) simulations are presented.

Andrey V. Khudchenko, M. Yu. Fominsky, Christopher Heiter +11 more

We present the design and results of characterization of a new sideband separating (2SB) mixer for 800-950 GHz, based on superconductor-insulator-superconductor (SIS) junctions. This is the first waveguide 2SB SIS mixer demonstrated at such a high frequency. The design is following the classical quadrature hybrid architecture, meanwhile additional attention was put on the reduction of reflections in the RF structure in order to minimize the RF imbalance, to achieve a high image rejection ratio (IRR). The RF waveguide block was manufactured by micromilling and populated by single-ended SIS mixers developed earlier for upgrade of the CHAMP+ high-band array on the APEX telescope. These SIS mixers have double-sideband (DSB) noise temperatures from 210 to 400 K. The assembled 2SB mixer yields a SSB noise temperature from 450 to 900 K, with an IRR above 15 dB in 95% of the band. Comparing the DSB and the SSB sensitivities, we find that the waveguide losses are as low as expected and do not exceed 0.6 dB. The presented mixer is a prototype for use in a 2SB dual polarization receiver planned for deployment on the APEX telescope.

Mamoru Kamikura, Yu Tomimura, Yutaro Sekímoto +8 more

Anthony R. Kerr, Shing-Kuo Pan, Stephane M. X. Claude +4 more

As the Atacama Large Millimeter/submillimeter Array (ALMA) nears completion, 73 dual-polarization receivers have been delivered for each of Bands 3 (84-116 GHz) and 6 (211-275 GHz). The receivers use sideband-separating superconducting Nb/Al-AlOx/Nb tunnel-junction (SIS) mixers, developed for ALMA to suppress atmospheric noise in the image band. The mixers were designed taking into account dynamic range, input return loss, and signal-to-image conversion (which can be significant in SIS mixers). Typical SSB receiver noise temperatures in Bands 3 and 6 are 30 and 60 K, respectively, and the image rejection is typically 15 dB.

Yasutaka Serizawa, Yutaro Sekímoto, Mamoru Kamikura +4 more