High-Resolution Radiometer for Remote Sensing of Solar Flare Activity from Low Earth Orbit Satellites

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause.For this Article Withdrawal Statement, please click on: https://ojs.bilpublishing.com/index.php/jasr/article/view/621Abstract: Solar flares, intense bursts of radiation, can disrupt the atmosphere and potentially affect communication, navigation and electrical systems. A newly developed miniaturised microwave radiometer used on a space-borne platform should offer astronomers unprecedented understanding of the largest explosive phenomena in our solar system. In this paper the activity and results of the EU funded research project FLARES are presented. Objective of FLARES has been the study, analysis and design of millimetre-wave (mm-wave) system-on-chip (SoC) radiometer for space-borne detection of solar flares. The proposed approach has contributed to reduce significantly the power consumption and weight with respect to the existing instruments for the observation and study of solar flares. In particular, the proposed SoC Dicke radiometer can achieve one order of magnitude improvement in terms of resolution, so allowing the detection of solar flares with relatively low intensity, i.e. about 100 times lower than those currently detected by the existing systems, owing to space-borne operations and the microchip-level miniaturization through silicon technology under space qualification

TERASENSE: THz device technology laboratory: final summary

The use of THz frequencies, particularly W and G band allows reaching higher resolution and deeper penetration in emerging applications like imaging, sensing, etc. The development of those new applications lays on reliable technologies, background of expertise and know-how. The CDS2008-00068 TERASENSE CONSOLIDER project has given the opportunity to extent upwards in frequency the previous background of the microwaves research group partners. This article summarizes the developments of the TERASENSE work package “THz Device Technology Laboratory”.This work was supported by the Spanish Ministerio de Ciencia e Innovación through the CONSOLIDER-INGENIO 2010 program reference CSD2008-00068 TERASENSE

Coherent Receiver Arrays for Astronomy and Remote Sensing

Monolithic Millimeter-wave Integrated Circuits (MMICs) provide a level of integration that makes possible the construction of large focal plane arrays of radio-frequency detectors—effectively the first “Radio Cameras”—and these will revolutionize radio-frequency observations with single dishes, interferometers, spectrometers, and spacecraft over the next two decades. The key technological advances have been made at the Jet Propulsion Laboratory (JPL) in collaboration with the Northrop Grumman Corporation (NGC). Although dramatic progress has been made in the last decade in several important areas, including (i) packaging that enables large coherent detector arrays, (ii) extending the performance of amplifiers to much higher frequencies, and (iii) reducing room-temperature noise at high frequencies, funding to develop MMIC performance at cryo-temperatures and at frequencies below 150GHz has dropped nearly to zero over the last five years. This has severely hampered the advance of the field. Moreover, because of the high visibility of < 150GHz cryogenic detectors in astrophysics and cosmology, lack of progress in this area has probably had a disproportionate impact on perceptions of the potential of coherent detectors in general. One of the prime objectives of the Keck Institute for Space Studies (KISS) is to select crucial areas of technological development in their embryonic stages, when relatively modest funding can have a highly significant impact by catalyzing collaborations between key institutions world-wide, supporting in-depth studies of the current state and potential of emerging technologies, and prototyping development of key components—all potentially leading to strong agency follow-on funding. The KISS large program “Coherent Instrumentation for Cosmic Microwave Background Observations” was initiated in order to investigate the scientific potential and technical feasibility of these “Radio Cameras.” This opens up the possibility of bringing support to this embryonic area of detector development at a critical phase during which KISS can catalyze and launch a coherent, coordinated, worldwide effort on the development of MMIC Arrays. A number of key questions, regarding (i) the importance and breadth of the scientific drivers, (ii) realistic limits on sensitivity, (iii) the potential of miniaturization into receiver “modules,” and (iv) digital signal processing, needed to be studied carefully before embarking on a major MMIC Array development effort led by Caltech/JPL/NGC and supported by KISS, in the hope of attracting adequate subsequent government funding. For this purpose a large study was undertaken under the sponsorship and aegis of KISS. The study began with a workshop in Pasadena on “MMIC Array Receivers and Spectrographs” (July 21–25, 2008)1, immediately after an international conference “CMB Component Separation and the Physics of Foregrounds” (July 14–18, 2008)2 that was organized in conjunction with the MMIC workshop. There was then an eight-month study period, culminating in a final “MMIC 2Workshop” (March 23–27, 2009).3 These workshops were very well attended, and brought together the major international groups and scientists in the field of coherent radio-frequency detector arrays. A notable aspect of the workshops is that they were well attended by young scientists—there are many graduate students and post-doctoral fellows coming into this area. The two workshops focused both on detailed discussions of key areas of interest and on the writing of this report. They were conducted in a spirit of full and impartial scrutiny of the pros and cons of MMICs, in order to make an objective assessment of their potential. It serves no useful purpose to pursue lines of technology development based on unrealistic and over-optimistic projections. This is crucially important for KISS, Caltech, and JPL which can only have real impact if they deliver on the promise of the technologies they develop. A broad range of opinions was evident at the start of the first workshop, but in the end a strong consensus was achieved on the most important questions that had emerged. This report reflects the workshop deliberations and that consensus. The key scientific drivers for the development of the MMIC technology are: (i) large angular-scale Bmode polarization observations of the cosmic microwave background—here MMICs are one of two key technologies under development at JPL, both of which are primary detectors on the recently-launched Planck mission; (ii) large-field spectroscopic surveys of the Galaxy and nearby galaxies at high spectral resolution, and of galaxy clusters at low resolution; (iii) wide-field imaging via deployment as focal plane arrays on interferometers; (iv) remote sensing of the atmosphere and Earth; and (v) wide-field imaging in planetary missions. These science drivers are discussed in the report. The most important single outcome of the workshops, and a sine qua non of this whole program, is that consensus was reached that it should be possible to reduce the noise of individual HEMTs or MMICs operating at cryogenic temperatures to less than three times the quantum limit at frequencies up to 150 GHz, by working closely with a foundry (in this case NGC) and providing rapid feedback on the performance of the devices they are fabricating, thus enabling tests of the effects of small changes in the design of these transistors. This kind of partnership has been very successful in the past, but can now be focused more intensively on cryogenic performance by carrying out tests of MMIC wafers, including tests on a cryogenic probe station. It was felt that a properly outfitted university laboratory dedicated to this testing and optimization would be an important element in this program, which would include MMIC designs, wafer runs, and a wide variety of tests of MMIC performance at cryogenic temperatures. This Study identified eight primary areas of technology development, including the one singled out above, which must be actively pursued in order to exploit the full potential of MMIC Arrays in a timely fashion: 1. Reduce the noise levels of individual transistors and MMICs to three times the quantum limit or lower at cryogenic temperatures at frequencies up to 150 GHz. 2. Integrate high-performing MMICs into the building blocks of large arrays without loss of performance. Currently factors of two in both noise and bandwidth are lost at this step. 3. Develop high performance, low mass, inexpensive feed arrays. 4. Develop robust interconnects and wiring that allow easy fabrication and integration of large arrays. 5. Develop mass production techniques suitable for arrays of differing sizes. 6. Reduce mass and power. (Requirements will differ widely with application. In the realm of planetary instruments, this is often the most important single requirement.) 7. Develop planar orthomode transducers with low crosstalk and broad bandwidth. 8. Develop high power and high efficiency MMIC amplifiers for LO chains, etc. Another important outcome of the two workshops was that a number of new collaborations were forged between leading groups worldwide with the object of focusing on the development of MMIC arrays

G-band waveguide to microstrip transition for MMIC integration

In recent years, Millimetre-Wave (MMW) frequencies (30-300 GHz) have been exploited for a variety of attractive applications such as astronomical observation, medical imaging, aircraft aided-control landing, security and concealed weapons detection. All this was also possible thanks to the advances in high frequency circuits where Monolithic Microwave Integrated Circuits (MMICs) represent a key factor. Systems working at MMW often use metal waveguides as interconnect elements and transitions are em- ployed to transfer the signals from these elements to the Radio Frequency (RF) circuits. The objective of this thesis is to design, fabricate and characterise electromagnetic transitions between rectangular waveguide (WR) and planar transmission lines at G-band frequencies (140-220 GHz). The first part of this work presents an overview of the electromagnetic properties of the atmosphere at MMW frequencies and their use for passive MMW imaging applications. Fundamental design concepts and prototypes of real-time imagers are also represented, based on the pioneering work carried out at QinetiQ Ltd. An extensive review of the scientific literature on waveguide transitions presents previous designs and architectures. The work proceeds through design, simulation, fabrication and measurements of G-band transitions highlighting advantages and disadvantages of different structures. The novel design of Elevated E-plane probes, used as waveguide to microstrip transitions in this work, extends the fabrication technique of MMIC air-bridges to build suspended metal structures and provides an additional optimising parameter to improve the reflection performance of the transition by decomposing the substrate influence on the metal probe. The innovative Elevated E-plane probe is fabricated on Semi-Insulated Gallium Arsenide (SI-GaAs) and it is MMIC-integrated, reducing system complexity and optimizing fabrication and assembly costs. The core of the thesis details the fabrication processes and procedures and a separate section describes the manufacture of G-band rectangular waveguide blocks that host the transitions. The overall fabrication is carried out using in-house facilities at the University of Glasgow without the aid of external facilities. Measured results are presented and discussed, validating design and simulations. This work has led to a successful design and fabrication of GaAs-integrated rectangular waveg- uide to microstrip line transition at G-band

Millimeter-Wave Band Pass Distributed Amplifier for Low-Cost Active Multi-Beam Antennas

Recently, there have been a great interest in the millimeter-wave (mmW) and terahertz (THz) bands due to the unique features they provide for various applications. For example, the mmW is not significantly affected by the atmospheric constraints and it can penetrate through clothing and other dielectric materials. Therefore, it is suitable for a vast range of imaging applications such as vision, safety, health, environmental studies, security and non-destructive testing. Millimeter-wave imaging systems have been conventionally used for high end applications implementing sophisticated and expensive technologies. Recent advancements in the silicon integrated and low loss material passive technologies have created a great opportunity to study the feasibility of low cost mmW imaging systems. However, there are several challenges to be addressed first. Examples are modeling of active and passive devices and their low performance, highly attenuated channel and poor signal to noise ratio in the mmW. The main objective of this thesis is to investigate and develop new technologies enabling cost-effective implementation of mmW and sub-mmW imaging systems. To achieve this goal, an integrated active Rotman lens architecture is proposed as an ultimate solution to combine the unique properties of a Rotman lens with the superiority of CMOS technology for fabrication of cost effective integrated mmW systems. However, due to the limited sensitivity of on-chip detectors in the mmW, a large number of high gain, wide-band and miniaturized mmW Low Noise Amplifiers (LNA) are required to implement the proposed integrated Rotman lens architecture. A unique solution presented in this thesis is the novel Band Pass Distributed Amplifier (BPDA) topology. In this new topology, by short circuiting the line terminations in a Conventional Distributed Amplifier (CDA), standing waves are created in its artificial transmission lines. Conventionally, standing waves are strongly avoided by carefully matching these lines to 50 Ω in order to prevent instability of the amplifier. This causes that a large portion of the signal be absorbed in these resistive terminations. In this thesis, it is shown that due to presence of highly lossy parasitics of CMOS transistor at the mmW the amplifier stability is inherently achieved. Moreover, by eliminating these lossy and noise terminations in the CDA, the amplifier gain is boosted and its noise figure is reduced. In addition, a considerable decrease in the number of elements enables low power realization of many amplifiers in a small chip area. Using the lumped element model of the transistor, the transfer function of a single stage BPDAs is derived and compared to its conventional counter part. A methodology to design a single stage BPDA to achieve all the design goals is presented. Using the presented design guidelines, amplifiers for different mmW frequencies have been designed, fabricated and tested. Using only 4 transistors, a 60 GHz amplifier is fabricated on a very small chip area of 0.105 mm2 by a low-cost 130 nm CMOS technology. A peak gain of 14.7 dB and a noise figure of 6 dB are measured for this fabricated amplifier. oreover, it is shown that by further circuit optimization, high gain amplification can be realized at frequencies above the cut-off frequency of the transistor. Simulations show 32 and 28 dB gain can be obtained by implementing only 6 transistors using this CMOS technology at 60 and 77 GHz. A 4-stage 85 GHz amplifier is also designed and fabricated and a measured gain of 10 dB at 82 GHz is achieved with a 3 dB bandwidth of 11 GHz from 80 to 91 GHz. A good agreement between the simulated and measured results verifies the accuracy of the design procedure. In addition, a multi-stage wide-band BPDA has been designed to show the ability of the proposed topology for design of wide band mmW amplifiers using the CMOS technology. Simulated gain of 20.5 dB with a considerable 3 dB bandwidth of 38 GHz from 30 to 68 GHz is achieved while the noise figure is less than 6 dB in the whole bandwidth. An amplifier figure of merit is defined in terms of gain, noise figure, chip area, band width and power consumption. The results are compared to those of the state of the art to demonstrate the advantages of the proposed circuit topology and presented design techniques. Finally, a Rotman lens is designed and optimized by choosing a very small Focal Lens Ratio (FL), and a high measured efficiency of greater than 30% is achieved while the lens dimensions are less than 6 mm. The lens is designed and implemented using a low cost Alumina substrate and conventional microstrip lines to ease its integration with the active parts of the system.1 yea

Integration of Planar Antennas with MMIC Active Frontends for THz Imaging Applications

In recent years, there has been constant growth in using THz frequencies or mm, sub- mm wavelengths for various applications such as: Astronomy, Atmospheric studies, security, bio-medical imaging. All these applications are now seen more feasible due to rapid enhancements of semi-conductor processing technologies. The state of the art MMIC processing techniques offering increased cut-off frequencies (> 500 GHz) of HEMT/HBT transistors open up new opportunities for integrating systems on chip along with an antenna for either Transmit/Receive architecture. The work carried out in this thesis mainly deals with the development of antenna structures which are compatible to available MMIC processes and have well defined interface with the active circuit components for microwave as well as mm/sub-mm wave applications. The thesis briefly reviews the THz applications and modern MMIC process techniques. There- after the emphasis is on various possible antenna structures which are feasible to fabricate with MMIC layer topologies. Such antenna structures are further compared in terms of their Gain, Bandwidth, Directivity, Gaussian Coupling Efficiency and Compactness. The main focus of the thesis is towards the development of multi-pixel front ends for THz imaging of concealed weapons for security applications. The requirement in this type of application is the heterodyne detection of reflected THz signals from the distant objects (> 20 m) with tightly integrated pixels constituting of antenna integrated receiver (Antenna + Mixer + LO-Multiplier chain) giving real-time video imaging. Thus the work is focused towards Co-design of Antenna + Mixer aiming towards compactness and minimizing physical area of pixel for tighter integration. One of the important results obtained in this work, is the integration of a Double Slot Antenna with a sub-harmonically pumped resistive mixer. The novelty in this work is the new geometrical placements of slots and microstrip feed network. This new topology has differential excitation of two parallel slots for broadside beam. With this new arrangement, the need of conventional power combining network from two slots is eliminated and the transistors can directly be placed between the two slots, thus minimizing the physical area. Such arrangement is fabricated and tested at frequency of 200 GHz using 50 nm HEMT process. Encouraging results are obtained with mixer conversion loss of ~15 dB with +3 dBm LO power at sub-harmonic of 100 GHz. The next key result of this thesis is the integration of a differential 2 x 2 array of microstrip patch antennas with Gilbert Cell type sub-harmonically pumped mixer. This integration is achieved using 250 nm DHBT process. Considering the antenna ohmic efficiency, mixer conversion loss and gain of IF amplifier; the overall receiver front end features a conversion gain of ~ 14±1 dB at frequency of 320 GHz when pumped with sub-harmonic LO of 160 GHz with ~4 dBm on chip power. This receiver was also tested close to 340 GHz, which is a target frequency for security imaging applications. Another important aspect of this work is to quantify the ability of a planar antenna to couple radiated power in to the THz quasi-optical system. This is often evaluated as Gaussian Coupling Efficiency or Gaussicity. Therefore MMIC integrated antennas are needed to be characterized in terms of their Gaussicity as well. For this, a new algorithm has been developed which accepts the far-field of the antenna as input and computes the optimum beam parameters (waist and its position) which maximize the Gaussicity. Furthermore this algorithm is applied to different antenna array configurations to quantify their radiation pattern for Gaussian Coupling Efficiency

Journal of Telecommunications and Information Technology, 2007, nr 1

kwartalni

Coherent Receiver Arrays for Astronomy and Remote Sensing

Monolithic Millimeter-wave Integrated Circuits (MMICs) provide a level of integration that makes possible the construction of large focal plane arrays of radio-frequency detectors—effectively the first “Radio Cameras”—and these will revolutionize radio-frequency observations with single dishes, interferometers, spectrometers, and spacecraft over the next two decades. The key technological advances have been made at the Jet Propulsion Laboratory (JPL) in collaboration with the Northrop Grumman Corporation (NGC). Although dramatic progress has been made in the last decade in several important areas, including (i) packaging that enables large coherent detector arrays, (ii) extending the performance of amplifiers to much higher frequencies, and (iii) reducing room-temperature noise at high frequencies, funding to develop MMIC performance at cryo-temperatures and at frequencies below 150GHz has dropped nearly to zero over the last five years. This has severely hampered the advance of the field. Moreover, because of the high visibility of < 150GHz cryogenic detectors in astrophysics and cosmology, lack of progress in this area has probably had a disproportionate impact on perceptions of the potential of coherent detectors in general. One of the prime objectives of the Keck Institute for Space Studies (KISS) is to select crucial areas of technological development in their embryonic stages, when relatively modest funding can have a highly significant impact by catalyzing collaborations between key institutions world-wide, supporting in-depth studies of the current state and potential of emerging technologies, and prototyping development of key components—all potentially leading to strong agency follow-on funding. The KISS large program “Coherent Instrumentation for Cosmic Microwave Background Observations” was initiated in order to investigate the scientific potential and technical feasibility of these “Radio Cameras.” This opens up the possibility of bringing support to this embryonic area of detector development at a critical phase during which KISS can catalyze and launch a coherent, coordinated, worldwide effort on the development of MMIC Arrays. A number of key questions, regarding (i) the importance and breadth of the scientific drivers, (ii) realistic limits on sensitivity, (iii) the potential of miniaturization into receiver “modules,” and (iv) digital signal processing, needed to be studied carefully before embarking on a major MMIC Array development effort led by Caltech/JPL/NGC and supported by KISS, in the hope of attracting adequate subsequent government funding. For this purpose a large study was undertaken under the sponsorship and aegis of KISS. The study began with a workshop in Pasadena on “MMIC Array Receivers and Spectrographs” (July 21–25, 2008)1, immediately after an international conference “CMB Component Separation and the Physics of Foregrounds” (July 14–18, 2008)2 that was organized in conjunction with the MMIC workshop. There was then an eight-month study period, culminating in a final “MMIC 2Workshop” (March 23–27, 2009).3 These workshops were very well attended, and brought together the major international groups and scientists in the field of coherent radio-frequency detector arrays. A notable aspect of the workshops is that they were well attended by young scientists—there are many graduate students and post-doctoral fellows coming into this area. The two workshops focused both on detailed discussions of key areas of interest and on the writing of this report. They were conducted in a spirit of full and impartial scrutiny of the pros and cons of MMICs, in order to make an objective assessment of their potential. It serves no useful purpose to pursue lines of technology development based on unrealistic and over-optimistic projections. This is crucially important for KISS, Caltech, and JPL which can only have real impact if they deliver on the promise of the technologies they develop. A broad range of opinions was evident at the start of the first workshop, but in the end a strong consensus was achieved on the most important questions that had emerged. This report reflects the workshop deliberations and that consensus. The key scientific drivers for the development of the MMIC technology are: (i) large angular-scale Bmode polarization observations of the cosmic microwave background—here MMICs are one of two key technologies under development at JPL, both of which are primary detectors on the recently-launched Planck mission; (ii) large-field spectroscopic surveys of the Galaxy and nearby galaxies at high spectral resolution, and of galaxy clusters at low resolution; (iii) wide-field imaging via deployment as focal plane arrays on interferometers; (iv) remote sensing of the atmosphere and Earth; and (v) wide-field imaging in planetary missions. These science drivers are discussed in the report. The most important single outcome of the workshops, and a sine qua non of this whole program, is that consensus was reached that it should be possible to reduce the noise of individual HEMTs or MMICs operating at cryogenic temperatures to less than three times the quantum limit at frequencies up to 150 GHz, by working closely with a foundry (in this case NGC) and providing rapid feedback on the performance of the devices they are fabricating, thus enabling tests of the effects of small changes in the design of these transistors. This kind of partnership has been very successful in the past, but can now be focused more intensively on cryogenic performance by carrying out tests of MMIC wafers, including tests on a cryogenic probe station. It was felt that a properly outfitted university laboratory dedicated to this testing and optimization would be an important element in this program, which would include MMIC designs, wafer runs, and a wide variety of tests of MMIC performance at cryogenic temperatures. This Study identified eight primary areas of technology development, including the one singled out above, which must be actively pursued in order to exploit the full potential of MMIC Arrays in a timely fashion: 1. Reduce the noise levels of individual transistors and MMICs to three times the quantum limit or lower at cryogenic temperatures at frequencies up to 150 GHz. 2. Integrate high-performing MMICs into the building blocks of large arrays without loss of performance. Currently factors of two in both noise and bandwidth are lost at this step. 3. Develop high performance, low mass, inexpensive feed arrays. 4. Develop robust interconnects and wiring that allow easy fabrication and integration of large arrays. 5. Develop mass production techniques suitable for arrays of differing sizes. 6. Reduce mass and power. (Requirements will differ widely with application. In the realm of planetary instruments, this is often the most important single requirement.) 7. Develop planar orthomode transducers with low crosstalk and broad bandwidth. 8. Develop high power and high efficiency MMIC amplifiers for LO chains, etc. Another important outcome of the two workshops was that a number of new collaborations were forged between leading groups worldwide with the object of focusing on the development of MMIC arrays

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance