High-performance quasi-optical GaAs monolithic mixer at 110 GHz

A novel GaAs monolithic integrated circuit mixer has been fabricated which is impedance matched to fundamental waveguide. It consists of a slot coupler, coplanar transmission line, surface-oriented Schottky-barrier diode, and RF bypass capacitor monolithically integrated on the GaAs surface. At 110 GHz, a monolithic mixer module mounted in the end of a waveguide horn has an uncooled double-sideband (DSB) mixer noise temperature of 339 K and conversion loss of 3.8 dB.     

A planar quasi-optical SIS receiver

A planar, quasi-optical SIS (superconductor-insulator-superconductor) receiver operating at 230 GHz is described. The receiver consists of a 2×5 array of half-wave dipole antennas with niobium-aluminum oxide-niobium SIS junctions on a quartz dielectric-filled parabola. The 1.4-GHz intermediate frequency is coupled from the mixer via coplanar strip transmission lines and 4:1 balun transformers. The receiver is operated at 4.2 K in a liquid helium immersion cryostat. Accurate measurements of the performance of single untuned array receiver elements are reported. A mixer noise temperature of 89 K DSB (double sideband), receiver noise temperature of 156 K DSB and conversion loss of 8 dB into a matched load have been obtained. This mixer noise temperature is approximately a factor of two larger than that of current state of the art waveguide mixers using untuned single junctions a the same frequency     

A three-dimensional quasi-optical self-oscillating mixer

A quasi-optical self-oscillating mixer (SOM) consisting of a pair of transistor-loaded grids mounted on opposite sides of a two-dimensional photonic crystal (PC) is presented. The PC facilitates mutual injection locking between the grids and extends the operating range of the SOM by minimizing injection locking to an external source. By combining this with electronic tuning of the free-running oscillation frequency, total elimination of the injection-locking range can be achieved. Radiation patterns at C-band also indicate the ability to detect RF signals in three dimensions     

Characterization of a 680–760 GHz SIS waveguide mixer

A heterodyne waveguide receiver employing 1 µm² Nb superconducting tunnel junctions with on chip integrated tuning structures is characterized from 680–760 GHz. Several different types of integrated tuning structures are investigated. Lowest DSB receiver noise temperatures of 310 K at 709 GHz and 400 K at 720 GHz are measured. Analysis of the data shows that the loss of the superconducting tuning structures has a major influence on the overall receiver performance. A 25% reduction in receiver noise temperature is observed if the mixer is cooled from 4.2 K to 2 K, which we attribute to the reduced loss of the superconducting microstrip lines at lower temperatures. The calculated performance of the different tuning structures is shown to be in good agreement with the actual receiver noise measurements.     

100 GHz mixer vertically integrated (stacked) SIS junction array

A Vertically Integrated Array (stacked array) of single windowSIS junctions (VIA SIS), based on a stacked five layer structure of Nb-AlO_x-Nb-AlO_x-Nb, has been fabricated and tested in a quasi optical mixer configuration at 106 GHz. This particular VIA SIS design has two stacked junctions fabricated by standard tri-layer process employing photolithography, reactive ion and wet etching processes. A simple expression for calculating the specific capacitance of single and arrayed SIS junctions is suggested. Due to the absence of interconnection leads between the individual junctions and reduced overall capacitance, compared to a single SIS junction, has the VIA SIS good future prospects for use in submillimeter wave SIS mixers The VIA SIS may be regarded as a lumped rather than a distributed structure at least up to the gap frequency at 730 GHz for Nb. DC-IV measurements show high quality of the Individual SIS junctions and good reproducibility of the array parameters over the substrate area. The first VIA SIS mixer experiments yielded a receiver noise temperature of 95 K (DSB) at a LO frequency of 106 GHz.     

Tunerless mixer mount for an SIS 80–120 GHz receiver

We have developed a 100 GHz band SIS receiver using a simple mixer mount design, which does not use variable RF tuning elements, such as a back short tuner or an E-plane tuner. The mixer mount structure was designed using calculations of the embedding impedance of the mixer mount, and of receiver performance, using the quantum theory of mixing under the 3-port approximation. The mixer mount structure we designed has a 1/7 reduced height waveguide and a “back short cavity”. We have constructed a receiver system using this tunerless mixer mount design, and we have measured the receiver noise temperatures for two different tunerless mixer mounts using arrays of four Nb/Al-AlOx/Nb junctions. For one of the two mixer mounts, we obtained very low noise receiver temperatures, 35–70 K, over the very wide frequency range of 80–120 GHz. We also show that, due to IF missmatching, the noise of the IF amplifier is the main contributor to the receiver noise temperature. We also compared the results of measurements with the results of our theoretical calculations. Our calculations reproduced the tendency of receiver performances very well. This tunerless mixer mount has application on the MM-Wave Array and in the multi-beam receiver.     

A 75 GHz to 115 GHz quasi-optical amplifier

A wideband quasi-optical amplifier employing two pyramidal back-to-back horns has been developed. Using a four-stage W-band low noise amplifier (LNA) designed and fabricated by Martin Marietta Laboratories, the quasi-optical amplifier gives a system gain greater than 11 dB from 86 GHz to 113 GHz without any low frequency oscillations. A peak system gain of 15.5 dB is measured at 102 GHz, and the measured noise figure of the system is 7.4 dB at 94 GHz. The quasi-optical amplifier design maintains the same polarization of the received and transmitted signal, provides better than -40 dB isolation, and can be fabricated monolithically at millimeter-wave frequencies     

A self-diplexing quasi-optical magic slot balanced mixer

Drawing on the principles of operation of the magic tee balanced mixer, a quasi-optical magic slot balanced mixer is proposed. The mixer exploits a diametrically fed annular slot radiator which radiates two orthogonal polarizations which are used as signal and local oscillator input ports. The idea has been tested at microwave frequencies. The measured radiation impedances, radiation patterns and conversion efficiency show that reasonable performance is readily obtained over a 30% bandwidth and that this quasi-optical balanced mixer is suitable for submillimeter wave applications     

Low noise SIS mixer for 230 GHz receivers of plateau de bure interferometer

We present a SIS mixer developed for 200 – 250 GHz band receivers of Plateau de Bure Interferometer. We demonstrate the minimum DSB receiver noise of 20 K at 220 GHz. The average receiver noise of 25 K is possible in 200 – 250 GHz range. The receiver conversion gain and output noise instability of 10^?4 on the time scale of 1 minute is comparable with the Shottky receivers performance. The minimum measured SIS mixer noise of about 10 K is close to the quantum limit. The waveguide SIS mixer with a single backshort has two junction array with inductively tuned junctions. The Nb/Al Oxide/Nb SIS junctions are 2.24 µm² each with the Josephson critical current density of 3.2 KA/cm². The thermal properties of the SIS mixer are studied. The mixer band of the low noise operation is in a good agreement with the design requirements.     

An SIS mixer for 90–120 GHz with gain and wide bandwidth

An SIS mixer for the 3 mm wavelength band has been developed. It has sufficient RF bandwidth to allow double-sideband operation at an IE of 1.4 GHz. Available gain of around 3 dB has been measured, along with mixer temperatures of 20 to 40K (both double sideband). The junctions were fabricated using a lead-alloy technology (Pb?In?Au/oxide/-Pb?Bi). Coupling and tuning structures were integrated onto a quartz substrate along with the junctions. The measurements were made at physical temperatures around 3.1K, achieved with a closed-cycle refrigerator.     

Low-noise SIS heterodyne receiver at 230 GHz

A 230 GHz laboratory receiver has been built using a superconductor-insulator-superconductor (SIS) junction as the mixing element. The junction is mounted in 4:1 reduced-height waveguide, terminated at one end with a circular adjustable backshort. Recent results indicate a receiver noise temperature of TR ? 120 K (DSB).     

GaAs optoelectronic mixer operation at 4.5 GHz

Optoelectronic heterodyne detection of high-frequency intensity modulation signals using a GaAs photoconductive mixer is reported. Flat response for optical modulation frequencies up to 4.5 GHz is observed for downconversion to a 500-MHz intermediate frequency using a low power local oscillator. Heterodyne responsivity was enhanced significantly over direct detection with the same photoconductive detector due to improved contact performance under RF bias.     

340 GHz固定调谐分谐波混频器

基于最新研制的小阳极结反向并联肖特基二极管芯片,设计和制造了320~360 GHz固定调谐分谐波混频器。混频器的结构采用的是传统电场（E）面腔体剖分式结构:将二极管芯片倒装焊粘在石英基片上,再用导电银胶将石英电路悬置粘结在混频器下半个腔体上。电路设计采用场路相结合的方法:用场仿真软件建立混频电路各个功能单元的S参数模型,将它们代入非线性电路仿真软件中与二极管结相结合进行混频器性能整体仿真优化。最终测试结果表明,谐波混频器的双边带在4~6 mW的本振功率驱动下,在320~360 GHz超过12%带宽范围内,双边带变频损耗均小于9 dB;混频器在310~340 GHz频带范围内,双边带噪声温度最低为780 K。声温度最低为780 K。     

92 GHz dual-polarized integrated horn antennas

A dual-polarized two-dimensional imaging array was designed for millimeter-wave applications. The dual-polarized design consists of two dipoles perpendicular to each other and suspended on the same membrane inside a pyramidal cavity etched in silicon. The dual-polarized antenna is fully monolithic with room available for processing electronics. The IF or video signals are taken out through a novel bias and feeding structure. The measured polarization isolation is better than 20 dB at 92 GHz, and the orthogonal channels show identical far-field patterns. The antenna is well suited for millimeter-wave polarimetric synthetic aperture radars (SARs) and high-efficiency balanced-mixer receivers     

A low-noise 492 GHz SIS waveguide receiver

In this paper we discuss the design and performance of an SIS waveguide receiver which provides low noise performance from 375 to 510 GHz. At its design frequency of 492 GHz the receiver has a double sideband noise temperature of ～172 K. By using embedded magnetic field concentrators, we are able to effectively suppress Josephson pair tunneling. Techniques for improving receiver performance are discussed.     

94GHzTE6,2模内置准光模式变换器

提出了可应用于94 GHz回旋管内部的TE6,2准光模式变换器.根据几何光学和矢量绕射理论编制了模拟其电磁行为的分析和优化程序.根据几何光学原理,设计了该模式变换器的初步结构参数,然后利用该优化程序获得了最优化的相关参数.优化结果表明,在94 GHz,该准光变换器功率转换效率约为85%,转换所得波束高斯含量高于70%.     

28 GHz omni-directional quasi-optical transmitter array

Omni-directional base stations are needed in many emerging wireless communication systems. This paper presents the first adaptation of a quasi-optical oscillator array for this purpose. A 28 GHz active oscillator element containing a modified Vivaldi endfire antenna is utilized as the unit cell. Twelve of these are incorporated into the circular array, which is powered from a single DC power supply. The array has a high combining efficiency and remains frequency-locked over a span of 600 MHz     

A 77 GHz SiGe sub-harmonic balanced mixer

A novel SiGe 77 GHz sub-harmonic balanced mixer is presented with a goal to push the technology to its limit [SiGe2-RF transistor (f/sub T/=80 GHz)]. This new topology uses a compact input network not only to achieve high isolation between the LO and RF ports, but also to result in excellent 2LO-RF isolation. The measured results demonstrate a conversion gain of 0.7 dB at 77 GHz with an LO power of 10 dBm at 38 GHz, LO-RF isolation better than 30 dB, 2LO-RF isolation of 25 dB, and a P/sub 1dB/ of -8 dBm. The mixer core consumes 4.4 mA at 5 V. The circuit demonstrates that SiGe sub-harmonic mixers have comparable performance with GaAs designs, at a fraction of the cost.     

A 345GHz SIS receiver for radio astronomy

A 345GHz superconductor insulator superconductor (SIS) tunnel junction receiver utilizing a full height rectangular waveguide mixer with two tuning elements, i.e. an E-plane and backshort tuner, has been constructed and installed on the Caltech Submillimeter Observatory 10m antenna on Mauna Kea, Hawaii. The receiver exhibits a best double side-band noise temperature response of 150K±20K (averaged over a 500 MHz IF bandwidth centered at 1.5GHz) at a design center frequency of 345GHz and at an ambient temperature of approximately 3.8K. Additional measurements show that the receiver has an excellent response at selected points within an RF input range of 280 to 363GHz.     

A lownoise 665 GHz SIS quasi-particle waveguide receiver

We report recent results on a 565–690 GHz SIS heterodyne receiver employing a 0.36µm² Nb/AlO _x /Nb SIS tunnel junction with high quality circular non-contacting backshort and E-plane tuners in a full height waveguide mount. No resonant tuning structures have been incorporated in the junction design at this time, even though such structures are expected to help the performance of the receiver. The receiver operates to at least the gap frequency of Niobium, ≈ 680 GHz. Typical receiver noise temperatures from 565–690 GHz range from 160K to 230K with a best value of 185K DSB at 648 GHz. With the mixer cooled from 4.3K to 2K the measured receiver noise temperatures decreased by approximately 15%, giving roughly 180K DSB from 660 to 680 GHz. The receiver has a full 1 GHz IF passband and has been successfully installed at the Caltech Submillimeter Observatory in Hawaii.