Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR) (original) (raw)
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A High Performance 700 GHz Feed Horn
Journal of Infrared, Millimeter, and Terahertz Waves, 2011
We present a design of a high performance horn operating at 700 GHz. The feed, which comprises three smooth-walled conical sections, is easy to machine and yet has comparable performance to a corrugated horn. The measured radiation patterns show high main beam circularity, low sidelobe level and good agreement with theoretical predictions. The cross-polar level is below −20 dB across a frequency bandwidth of 140 GHz. The new design allows the fabrication of high performance, large format feed arrays cheaply and rapidly.
Inexpensive receiver components for millimeter and submillimeter wavelengths
1997
In recent years there has been excellent progress in the development of millimeter and submillimeter wavelength components such as mixers and multipliers. Particularly, SIS mixers have yielded sensitivity near the quantum limit at frequencies approaching 1 THz and hotelectron bolometric mixers now promise similar performance above 1 'THz. However, for many applications the cost of building and maintaining cryogenic systems is prohibitive. In such cases, GaAs Schottky diode technology remains a very attractive option, provided the sensitivity requirement is not so great, particularly now that planar (whiskerless) diodes are yielding good performance. However, even in the case of Schottky mixers and multipliers, the cost of machining the waveguide blocks can be prohibitive, particularly at THz frequencies and/or when array applications are considered. In this paper we summarize two techniques which allow low cost manufacturing of millimeter and submillimeter wavelength components.
Construction and Measurement of a 31.3–45 GHz Optimized Spline-profile Horn with Corrugations
Journal of Infrared, Millimeter, and Terahertz Waves, 2011
A corrugated spline-profile horn has been designed to meet the stringent specifications and constraints of a receiver for Band 1 (31.3-45 GHz) of the Atacama Large Millimeter Array (ALMA). Given the physical restrictions of the receiver, the horn will be located behind a focusing lens placed 191 mm over its aperture. After this first focusing stage, the horn must have a reflection coefficient less than −20 dB and the cross-polarization not exceeding the −30 dB level in the entire frequency range. The side-lobes should be less than −25 dB at all frequencies and its half power beamwidth must be approximately 24 • at 31.3 GHz and 16 • at 45 GHz. The horn has been constructed using the split-block technique and characterized in a near-field scanner setup. The results show an excellent performance complying with all the requirements.
SWI 1200/600 GHz highly integrated receiver front-ends
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The band 1 (530-625 GHz) and band 2 (1080-1275 GHz) subharmonic receiver front-ends for the submillimeter wave instrument (SWI), which is part of the European Space Agency (ESA) Jupiter Icy moons Explorer (JUICE) class-L mission, are currently being developed by Omnisys Instruments AB. The front-end prototypes for the two band 1 receiver channels, which is the current instrument baseline, comprise a subharmonic Schottky diode terahertz monolithically integrated circuit (TMIC) mixer, and a module integrated intermediate frequency (IF) InP HEMT MMIC cryogenic low noise amplifier (LNA) design from Low Noise Factory, fabricated at Chalmers University of Technology. Measurements show a typical room temperature performance of ~1500 K double sideband (DSB) with a minimum receiver noise temperature of around 1100 K. The receiver front-end module is operated with only 1-2 mW of local oscillator power over the full band and has a total power dissipation of below 40 mW with about 30 dB of conv...
A 135-150-GHz Frequency Tripler Using SU-8 Micromachined WR-5 Waveguides
IEEE Transactions on Microwave Theory and Techniques
This article presents a 135-150-GHz Schottky diode-based bias-less frequency tripler based on SU-8 micromachined WR-5 waveguides. The waveguides consist of five 432-µmthick silver-plated SU-8 layers, which house the diode chip and form the output matching network. The input matching circuit is realized in a computer numerical control (CNC) milled waveguide filter, which also provides support and thermal sink to the SU-8 waveguides. Considering the low thermal conductivity of the SU-8 material, auxiliary metallic thermal paths are designed, and the impact of these is discussed through thermal modeling. The thermal simulations show that under 50-mW power dissipation in the diode anodes, the maximum temperature of the SU-8 tripler is predicted to be 346 K at the diode junction, only 7 K higher than in an entirely metal equivalent. The tripler was measured to have a conversion loss of 16-18 dB and the input return loss is better than 18 dB. This work demonstrates that SU-8 micromachined waveguides can be used to package high-frequency semiconductor components, which, like other photolithography-based processes such as silicon deep reactive ion etching (Si-DRIE), has the potential for submicrometer feature resolution.
IEEE Transactions on Microwave Theory and Techniques, 1998
We report on a 850 GHz SIS heterodyne receiver employing a RF tuned niobium tunnel junction with a current density of 14kA/cm 2 , fabricated on a 1 µm Si 3 N 4 supporting membrane. Since the mixer is designed to be operated well above the superconducting gap frequency of niobium (2 /h ≈ 690 GHz), special care has been taken to minimize niobium transmission line losses. Both Fourier Transform Spectrometer measurements of the direct detection performance and calculations of the IF output noise with the mixer operating in heterodyne mode, indicate an absorption loss in the niobium film of about 6.8 dB at 822 GHz. These results are in reasonably good agreement with the loss predicted by the Mattis-Bardeen theory in the extreme anomalous limit. From 800-840 GHz we report uncorrected receiver noise temperatures of 518K or 514K when we use Callen & Welton's law to calculate the input load temperatures. Over the same frequency range, the mixer has a 4 dB conversion loss and 265K ± 10K noise temperature. At 890 GHz the sensitivity of the receiver has degraded to 900K, which is primarily the result of increased niobium film loss in the RF matching network. When the mixer was cooled from 4.2K to 1.9K the receiver noise temperature improved about 20% to 409K DSB. Approximately half of the receiver noise temperature improvement can be attributed to a lower mixer conversion loss, while the remainder is due to a reduction in the niobium film absorption loss. At 982 GHz we measured a receiver noise temperature of 1916K.
A Low Cross-Polarization Smooth-Walled Horn With Improved Bandwidth
IEEE Transactions on Antennas and Propagation, 2010
Corrugated feed horns offer excellent beam symmetry, main beam efficiency, and crosspolar response over wide bandwidths, but can be challenging to fabricate. An easier-tomanufacture smooth-walled feed is explored that approximates these properties over a finite bandwidth. The design, optimization and measurement of a monotonically-profiled, smoothwalled scalar feedhorn with a diffraction-limited-7° FWHM is presented. The feed was demonstrated to have low cross polarization (<-30 dB) across the frequency range 33-45 GHz (30% fractional bandwidth). A return loss better than-28 dB was measured across the band.
An SIS-based sideband-separating heterodyne mixer optimized for the 600 to 720 GHz band
Journal of Physics: Conference Series, 2008
The Atacama Large Millimeter Array (ALMA) is the largest radio astronomical enterprise ever proposed. When completed, each of its 64 constituting radio-telescopes will be able to hold 10 heterodyne receivers covering the spectroscopic windows allowed by the atmospheric transmission at the construction site, the altiplanos of the northern Chilean Andes. In contrast to the sideband-separating (2SB) receivers being developed at low frequencies, double-side-band (DSB) receivers are being developed for the highest two spectroscopic windows (bands 9 and 10). Despite of the well known advantages of 2SB mixers over their DSB counterparts, they have not been implemented at the highest-frequency bands as the involved dimensions for some of the radio frequency components are prohibitory small. However, the current state-of-the-art micromachining technology has proved that the structures necessary for this development are attainable. Here we report the design, modeling, realization, and characterization of a 2SB mixer for band 9 of ALMA (600 to 720 GHz). At the heart of the mixer, two superconductor-insulator-superconductor (SIS) junctions are used as mixing elements. The constructed instrument presents an excellent performance as shown by two important figures of merit: noise temperature of the system and side band ratio, both of them within ALMA specifications. design, modelling, realization, and characterization of a 2SB mixer for frequencies from 600 to 720 GHz corresponding to band 9 of ALMA [1]. 2. Design and Modelling From a variety of possible 2SB schemes, we have selected the configuration shown in figure 1. The RF to be detected is brought to a hybrid which separates the signal into two branches of equal amplitude but with a phase separation of 90°. Each branch is coupled with the LO signal and mixed into two non-linear devices (SIS junctions in this case). The resulting IF signals are brought to a new 90° hybrid after which two new IF signals are obtained corresponding to USB and LSB, respectively. We have opted for waveguide technology for the construction of the RF components and planar stripline for the IF filtering and matching parts. Each one the RF components and the planar IF system were modeled independently using commercial microwave-analysis software (Microwave Studio *). The dimensions of every RF component were selected for an optimal performance in the 600−720 GHz range. On the other hand, the IF signal is intended to cover 4−8 GHz.
Experimental Investigation of a Low-Cost, High Performance Focal-Plane Horn Array
IEEE Transactions on Terahertz Science and Technology, 2012
In previous work, we have described novel smoothwalled multiple flare-angle horns designed using a genetic algorithm. A key feature of these horns is that they can be manufactured very rapidly and cheaply in large numbers, by repeated direct drilling into a single plate of aluminum using a shaped machine tool. The rapid manufacturing technique will enable the construction of very low cost focal-plane arrays, offering an alternative to conventional electroformed corrugated horn arrays. In order to experimentally demonstrate the new technology, we constructed a 230 GHz focal-plane array comprising 37 smoothwalled horns fabricated by direct drilling. We present the measured beam patterns for a large sample of these horns across the array, demonstrating the suitability of our manufacturing techniques for large format arrays. We have measured the cross coupling between adjacent feeds and have shown that it is negligible. We also present high quality beam patterns measured for a much smaller 700 GHz horn, showing the promise of the extending this technology to THz frequencies.