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We report on the development of wideband receivers for the Submillimeter Array (SMA). The current generation of SMA receiver offers an intermediate frequency (IF) of 4–14 GHz. We have further pushed the frontier of wideband SIS mixing, by developing a low noise receiver with an IF of 4–18 GHz.
A wideband profiled corrugated feedhorn was developed for multichroic applications. This feedhorn features a return loss of better than −25 dB and cross polarization peaks below −30 dB, over a fractional bandwidth of >50%. Its performance is close to that of the ring-loaded corrugated feedhorn; however, the design presented is much easier to fabricate at millimeter wavelengths.
Tucker's theory of quantum mixing can be extended to model distributed series connected SIS mixers, which offer a lower capacitance and a higher dynamic range. These mixers have wider IF bandwidth than single junction mixer. Coupled with the emerging ultra-wide band technologies in low noise amplifier and fast digital signal processing, they open a new frontier of ultra-wide band receivers. We report...
The IF bandwidth of an SIS mixer is limited by its capacitance. A series distributed design reduces the effective junction capacitance and the junctions can be reused as low impedance matching elements, limiting the capacitance of the RF matching network. In this paper, the analysis of this novel design is explored. Two receivers incorporating two types of series distributed SIS mixers were tested...
A 660 GHz local oscillator (LO) sub-system for the submillimeter array is designed, tested and aligned in the laboratory by optical and radio alignment. The LO unit employs a cascade tuneless frequency doubler-tripler based on the planar GaAs Schottky diode technology. It is found that a phase shifter inserted between the first and second multiplier stages can improve the frequency response of the...
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