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1. Prototype finline-coupled TES bolometers for CLOVER

Author

Audley, Michael D., Barker, Robert W., Crane, Michael, Dace, Roger, Glowacka, Dorota, Goldie, David J., Lasenby, Anthony N., Stevenson, Howard M., Tsaneva, Vassilka, Withington, Stafford, Grimes, Paul, Johnson, Bradley, Yassin, Ghassan, Piccirillo, Lucio, Pisano, Giampaolo, Duncan, William D., Hilton, Gene C., Irwin, Kent D., Reintsema, Carl D., and Halpern, Mark

Subjects
Astrophysics
Abstract

CLOVER is an experiment which aims to detect the signature of gravitational waves from inflation by measuring the B-mode polarization of the cosmic microwave background. CLOVER consists of three telescopes operating at 97, 150, and 220 GHz. The 97-GHz telescope has 160 feedhorns in its focal plane while the 150 and 220-GHz telescopes have 256 horns each. The horns are arranged in a hexagonal array and feed a polarimeter which uses finline-coupled TES bolometers as detectors. To detect the two polarizations the 97-GHz telescope has 320 detectors while the 150 and 220-GHz telescopes have 512 detectors each. To achieve the target NEPs (1.5, 2.5, and 4.5x10^-17 W/rtHz) the detectors are cooled to 100 mK for the 97 and 150-GHz polarimeters and 230 mK for the 220-GHz polarimeter. Each detector is fabricated as a single chip to ensure a 100% operational focal plane. The detectors are contained in linear modules made of copper which form split-block waveguides. The detector modules contain 16 or 20 detectors each for compatibility with the hexagonal arrays of horns in the telescopes' focal planes. Each detector module contains a time-division SQUID multiplexer to read out the detectors. Further amplification of the multiplexed signals is provided by SQUID series arrays. The first prototype detectors for CLOVER operate with a bath temperature of 230 mK and are used to validate the detector design as well as the polarimeter technology. We describe the design of the CLOVER detectors, detector blocks, and readout, and present preliminary measurements of the prototype detectors performance., Comment: 4 pages, 6 figures; to appear in the Proceedings of the 17th International Symposium on Space Terahertz Technology, held 10-12 May 2006 in Paris

Published
2006

2. TES imaging array technology for CLOVER

Author

Audley, Michael D., Barker, Robert W., Crane, Michael, Dace, Roger, Glowacka, Dorota, Goldie, David J., Lasenby, Anthony N., Stevenson, Howard M., Tsaneva, Vassilka, Withington, Stafford, Grimes, Paul, Johnson, Bradley, Yassin, Ghassan, Piccirillo, Lucio, Pisano, Giampaolo, Duncan, William D., Hilton, Gene C., Irwin, Kent D., Reintsema, Carl D., and Halpern, Mark

Subjects
Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

CLOVER is an experiment which aims to detect the signature of gravitational waves from inflation by measuring the B-mode polarization of the cosmic microwave background. CLOVER consists of three telescopes operating at 97, 150, and 220 GHz. The 97-GHz telescope has 160 horns in its focal plane while the 150 and 220-GHz telescopes have 256 horns each. The horns are arranged in a hexagonal array and feed a polarimeter which uses finline-coupled TES bolometers as detectors. To detect the two polarizations the 97-GHz telescope has 320 detectors while the 150 and 220-GHz telescopes have 512 detectors each. To achieve the required NEPs the detectors are cooled to 100 mK for the 97 and 150-GHz polarimeters and 230 mK for the 220-GHz polarimeter. Each detector is fabricated as a single chip to guarantee fully functioning focal planes. The detectors are contained in linear modules made of copper which form split-block waveguides. The detector modules contain 16 or 20 detectors each for compatibility with the hexagonal arrays of horns in the telescopes' focal planes. Each detector module contains a time-division SQUID multiplexer to read out the detectors. Further amplification of the multiplexed signals is provided by SQUID series arrays. The first prototype detectors for CLOVER operate with a bath temperature of 230 mK and are used to validate the detector design as well as the polarimeter technology. We describe the design of the CLOVER detectors, detector blocks, and readout, and give an update on the detector development., Comment: 9 pages, 7 figures, SPIE Orlando 24-31 May 2006, Conference 6275

Published
2006
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5. Electromagnetic performance comparisons of 0.85 THz integrated bias-tee SIS mixers with twin-junction and end-loaded tuning schemes

Author

Tan, Boon Kok, Rudakov, Kirill, Koshelets, Valery P., Khudchenko, Andrey, Baryshev, Andrey M., Yassin, Ghassan, Zmuidzinas, Jonas, Gao, Jian-Rong, and Astronomy

Subjects
Electromagnetism, Millimetre/Sub-Millimetre Astronomy, Heterodyne Technique, Terahertz Technology, Superconductor-Insulator-Superconductor (SIS) mixer
Abstract

We compare the design of two 0.85 THz SIS mixers fed with a radial probe antenna aligned to the E-Plane of the input full-height rectangular waveguide connected to a drilled smooth-walled horn. Both designs employ the same 0.5 μm2hybrid Nb/AlN/NbN tunnel junction technology, sandwiched between a NbTiN ground and aluminium wiring layer fabricated on top of a 40 μm quartz substrate. The two designs is differed by how we tune out the unwanted junction capacitance for broadband performance. The first design uses the commonly-used twin-junction tuning scheme; whilst the second design utilises an end-loaded scheme. We successfully achieve close to 2× the double sideband quantum noise performance for both schemes, but the twin-junction design is less sensitive to fabrication accuracy of planar circuit components utilised. However, the end-loaded design offers a much better IF bandwidth performance, almost twice wider than the twin-junction design. The need for an ultra-wide IF bandwidth mixer is becoming more pressing and important for the future and up-coming upgrades of various millimetre (mm) and sub-mm astronomical instruments, hence we conclude that the end-loaded design is a better solution for the THz heterodyne mixing applications.

Published
2022
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9. A 700-GHz SIS antipodal finline mixer fed by a pickett-potter horn-reflector antenna

Author

Kittara, Phichet, Grimes, Paul, Yassin, Ghassan, Withington, Stafford, Jacobs, Karl, and Wulff, Stephan

Subjects
Antennas (Electronics) -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

We report the successful operation of a superconductor-insulator-superconductor (SIS) finline mixer operating near the superconducting energy gap of Nb. The mixer employs a new type of Pickett-Potter horn-reflector (PPHR) antenna, which exhibits low sidelobes and low cross-polarization levels, and yet is easy to fabricate. The SIS tunnel junction and all of the integrated superconducting tuning circuits are fabricated from Nb using planar-circuit technology. The mixer employs an antipodal finline section, deposited on one side of a quartz substrate, which transforms the high impedance of the waveguide ([approximately equal to] 300 [ohm]) to the low impedance of the microstrip line ([approximately equal to] 20 [ohm]). The Nb/Al-oxide/Nb tunnel junction is fabricated at the same time as the finline circuit. In this paper, we describe the design and testing of the mixer, and pay particular attention to the electromagnetic design of the PPHR antenna. We investigate the noise temperature and gain of the mixer over 642-714 GHz, and analyze the experimental results using rigorous theories that were developed specifically for the purpose. Our investigation demonstrates that finline mixers have good performance both below and above the superconducting energy gap. Index Terms--Finline transitions, horn antennas, submillimeter-wave receivers, superconductor-insulator-superconductor (SIS) mixers.

Published
2004

12. A two-element horn-reflector antenna for cosmic microwave background astronomy

Author

Dicker, Simon R., Yassin, Ghassan, and Withington, Stafford

Subjects
Cosmic background radiation -- Research, Earth stations -- Design and construction, Business, Computers, Electronics, Electronics and electrical industries
Abstract

We present the design of a novel two-element horn-reflector antenna, which has been used on an interferometer built for studying the anisotropy in the cosmic microwave background at an angular scale of [approximately equal to] 2 [degrees] and a frequency of 33 GHz. The design consists of a pair of closely packed parabolic mirrors fed by two rectangular corrugated horns, each at an offset angle of 75 [degrees] to the axis of its mirror. The offset angle and the horn-reflector dimensions were chosen so that the antenna has elliptical primary beams producing a synthesized beam with circular lobes. We have designed and tested the radiation pattern of the individual antennas and the performance of the interferometer using bright radio sources. Our measurements revealed that the individual antennas have low sidelobes and that the crosstalk between the two elements of the interferometer is less than -80 dB. We therefore conclude that this design is suitable for the required astronomical application. Index Terms--Horn antenna design.

Published
2002

18. The molecular beam maser employing quasi-optical resonators : oscillation behaviour and spectroscopic applications

Author

Yassin, Ghassan

Subjects
539.7, QC Physics
Abstract

The spectroscopic and oscillation properties of the molecular Beam maser, employing quasi-optical resonators are investigated. A new type of cavity, the roof-top resonator, is introduced for molecular beam work. The theoretical discussion reveals that it exhibits low diffraction losses at microwave frequencies. Its successful operation in conjunction with a single beam ammonia maser shows that the cavity is ideal for molecular beam spectroscopy in the cm-mm-wave spectral region. Although the oscillation behaviour of the ammonia maser operated with disc resonators has been throughly investigated, very little has hitherto been known about the mode polarization properties of these resonators, especially at microwave frequencies. The employment of a new method of detection in the present work, facilitated the observation of the vectorial aspect of the maser oscillation. Such observations have led to the successful interpretation of unusual phenomena in the maser oscillation characteristics, for example, the drop in the amplitude of oscillation at high levels of excitation and the jumps in the frequency of oscillation while tuning the cavity through the molecular resonance. Investigation of the maser oscillation polarization also revealed some new effects directly linked to those previously observed in He-Ne lasers. These included oscillation polarization bistability and rotation of the plane of polarization In a weak axial magnetic field. These effects strongly influence the maser frequency stability and thus its applications as a frequency standard. Finally, the isotropic properties of the disc resonator were exploited to enhance spectrometer sensitivity. This was done by the use of Faraday rotation as a basis for a new type of molecular beam maser spectrometer. An alternative method, employed detection of weak spectral lines via the low-noise elliptically polarized maser oscillation.

Published
1981

19. Far-Infrared Optics Design & Verification

Author

OʼSullivan, Créidhe, Atad-Ettedgui, Eli, Duncan, William, Henry, David, Jellema, Willem, Murphy, J. Anthony, Trappe, Neil, van de Stadt, Herman, Withington, Stafford, and Yassin, Ghassan

Published
2002

20. The electrical characteristics of a conical horn-reflector antenna employing a corrugated horn

Author

Yassin, Ghassan, Robson, Martin, and Duffett-Smith, Peter J.

Subjects
Earth stations -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

The electrical properties of a conical horn-reflector antenna of 2 degrees-3 degrees beam width have been investigated over the frequency range of 12-18 GHz. We show that the employment of a corrugated horn reduces the characteristic spillover side lobe of the conical horn-reflector antenna by 15 dB and yields excellent main beam circularity over the full Ku band. This results from the taper of the field amplitude toward the edges of the horn aperture in both the E-plane and the H-plane illumination. The performance of the antenna makes it suitable for use in closely packed interferometers for radio astronomy.

Published
1993

29. A 700 GHz unilateral finline SIS mixer fed by a multi-flare angle smooth-walled horn

Author

Tan, Boon-Kok, Yassin, Ghassan, Grimes, Paul, Leech, Jamie, Jacobs, Karl, Withington, Stafford, Tacon, Mike, Groppi, Christopher, Zmuidzinas, Jonas, Holland, Wayne S., and Zmuidzinas, Jonas

Subjects
Materials science, business.industry, Bandwidth (signal processing), Silicon on insulator, Feed horn, Chip, Radiation pattern, law.invention, Optics, Planar, law, business, Waveguide, Electronic circuit
Abstract

We present the design of a broadband superconductor-insulator-superconductor (SIS) mixer operating near 700 GHz. A key feature of our design is the utilisation of a new type of waveguide to planar circuit transition comprising a unilateral finline taper. This transition is markedly easier to design, simulate and fabricate than the antipodal finline we employed previously. The finline taper and the superconducting circuitry are deposited on a 15 μm thick silicon substrate. The employment of the very thin substrate, achieved using Silicon-On-Insulator (SOI) technology, makes it easy to match the incoming signal to the loaded waveguide. The lightweight mixer chip is held in the E-plane of the waveguide using gold beam leads, avoiding the need for deep grooves in the waveguide wall. This new design yields a significantly shorter chip, free of serrations and a wider RF bandwidth. Since tuning and all other circuits are integrated on the mixer chip, the mixer block is extremely simple, comprising a feed horn and a waveguide section without any complicated mechanical features. We employ a new type of smooth-walled horn which exhibits excellent beam circularity and low cross polarisation, comparable to the conventional corrugated horn, and yet is easier to fabricate. The horn is machined by standard milling with a drill tool shaped into the horn profile. In this paper, we describe the detailed design of the mixer chip including electromagnetic simulations, and the mixer performance obtained with SuperMix simulations. We also present the preliminary measurements of the smooth-walled horn radiation patterns near the mixer operating frequencies.

Published
2016

33. Dyadic Analysis of Partially Coherent Submillimeter-Wave Antenna Systems

Author

Withington, Stafford, Yassin, Ghassan, and Murphy, J. Anthony

Subjects
Antennas (Electronics) -- Research, Coherent states -- Research, Submillimeter waves -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

We describe a procedure for simulating the behavior of partially coherent submillimeter-wave antenna systems. The procedure is based on the principle that the second-order statistical properties of any partially coherent vector field can be decomposed into a sum of fully coherent, but completely uncorrelated, natural modes. Any of the standard electromagnetic analysis techniques--physical optics, geometrical theory of diffraction, etc.--can be used to propagate and scatter the modes individually, and the statistical properties of the total transformed field reconstructed at the output surface by means of superposition. In the case of modal optics--plane waves, Gaussian optics, waveguide mode matching, etc.--the properties of the field can be traced directly by means of scattering matrices. The overall procedure is of considerable value for calculating the behavior of astronomical instruments comprising planar and waveguide multimode bolometers, submillimeter-wave optical components, and large reflecting antennas. Index Terms--Partial coherence, submillimeter-wave antennas.

Published
2001

34. A 350-GHz SIS Antipodal Finline Mixer

Author

Yassin, Ghassan, Withington, Stafford, Buffey, Matthew, Jacobs, K., and Wulff, S.

Subjects
Superconductive devices -- Research, Mixers (Electronics) -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

In this paper, we describe the design and operation of a 350-GHz finline superconductor-insulator-superconductor mixer. The mixer is fed by a horn-reflector antenna, and the superconducting circuit is fabricated using planar-circuit technology and fully integrated tuning. An important feature of the mixer is that it employs an antipodal finline section, deposited on one side of a quartz substrate, which transforms the high impedance of the waveguide ([approximately equals] 300 [Omega]) to the low impedance of the microstrip ([approximately equals] 20 [Omega]). The Nb/Al-oxide/Nb tunnel junction is fabricated at the same time as the finline circuit. In this paper, we describe the design procedure in some detail. We pay particular attention to the synthesis of the finline taper and the electromagnetic design of the horn-reflector antenna. We have tested a finline mixer over the frequency range of 330-370 GHz and measured a receiver noise temperature of 90 K, which remained unchanged over the whole frequency range. Our investigation has demonstrated that it is possible to make superconducting finline mixers for frequencies as high as 350 GHz.

Published
2000

42. Experimental Verification of Electromagnetic Simulations of a HIFI Mixer Sub-Assembly

Author

Jellema, Willem, Wesselius, P., Withington, Stafford, Yassin, Ghassan, Murphy, J. Anthony, O'Sullivan, Créidhe, Trappe, Neil, Peacocke, T., and Leone, B.

Abstract

Phase II of the study "Far-Infrared Optics Design & Verification", commissioned by the European Space Agency (ESA), we investigate the ability of several commercial software packages (GRASP, CODEV, GLAD and ASAP) to predict the performance of a representative example of a submillimeter-wave optical system. In this paper, we use the software packages to predict the behaviour of a Mixer Sub-Assembly (MSA) of HIFI, and we compare the simulations with near-field measurements at 480 GHz. In order to be able to distinguish between the predictions of the packages, we move the corrugated horn of the MSA through its nominal focus position. A unique feature of the experimental arrangement is that the measured position of every field point is known absolutely to within fractions of a wavelength. In this paper we present the results of this through-focus experiment, which give a good first-order indication of the agreement between measured and simulated behaviour of a typical submillimeter-wave optical system.

Published
2003

45. A 700 GHz unilateral finline SIS mixer fed by a multi-flare angle smooth-walled horn

Author

Holland, Wayne S., Zmuidzinas, Jonas, Tan, Boon-Kok, Yassin, Ghassan, Grimes, Paul, Leech, Jamie, Jacobs, Karl, Withington, Stafford, Tacon, Mike, Groppi, Christopher, Holland, Wayne S., Zmuidzinas, Jonas, Tan, Boon-Kok, Yassin, Ghassan, Grimes, Paul, Leech, Jamie, Jacobs, Karl, Withington, Stafford, Tacon, Mike, and Groppi, Christopher

Abstract

We present the design of a broadband superconductor-insulator-superconductor (SIS) mixer operating near 700 GHz. A key feature of our design is the utilisation of a new type of waveguide to planar circuit transition comprising a unilateral finline taper. This transition is markedly easier to design, simulate and fabricate than the antipodal finline we employed previously. The finline taper and the superconducting circuitry are deposited on a 15 mu m thick silicon substrate. The employment of the very thin substrate, achieved using Silicon-On-Insulator (SOI) technology, makes it easy to match the incoming signal to the loaded waveguide. The lightweight mixer chip is held in the E-plane of the waveguide using gold beam leads, avoiding the need for deep grooves in the waveguide wall. This new design yields a significantly shorter chip, free of serrations and a wider RF bandwidth. Since tuning and all other circuits are integrated on the mixer chip, the mixer block is extremely simple, comprising a feed horn and a waveguide section without any complicated mechanical features. We employ a new type of smooth-walled horn which exhibits excellent beam circularity and low cross polarisation, comparable to the conventional corrugated horn, and yet is easier to fabricate. The horn is machined by standard milling with a drill tool shaped into the horn profile. In this paper, we describe the detailed design of the mixer chip including electromagnetic simulations, and the mixer performance obtained with SuperMix simulations. We also present the preliminary measurements of the smooth-walled horn radiation patterns near the mixer operating frequencies.

Published
2010

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