Passive radiometers are well-known instruments used in the characterization of soil, sea surfaces and remote sensing of the earth atmosphere with satellites or airplanes. The instrument described in this article is a dual-polarised superheterodyne radiometer operating around 93 GHz. It is placed on a structure to measure road surface conditions (ice, water or oil) in a laboratory-controlled environment. This radiometer measures the reflected and emitted radiations from the road surface (asphalt and concrete) and the background temperature, in two orthogonal polarizations (H and V). The difference in the dielectric properties of the ice, oil and water from dry road surface allows to distinguish them efficiently. This kind of technique can be used for road surface recognition in all weather conditions and does not require presence of daylight or other sources of illumination. In this paper, calibration procedures and radiometric characterisations of the radiometer are studied in order to select the best and simpler method to operate the radiometer. It was found that calibrating the radiometer with only one blackbody target or using a table of gain and system noise temperature is sufficiently accurate over a long time to be able to distinguish dry from ice or water covered surfaces. The laboratory results are showing a high difference in the brightness temperature between road surface covered with ice, water or oil and the dry road surface. No ambiguities between those conditions exist but potential limitations could rise, for example if the road surface roughness changes during a measurement. Those promising results validate the potential of using radiometer for road safety and the automotive industry. The presented laboratory measurements are the first step towards the implementation of the instrument into a moving vehicle for alerting drivers ahead of unforeseen dangers.
A 110-170 GHz transceiver is designed and fabricated in a 130 nm SiGe BiCMOS technology. The transceiver operates as an amplifier for transmitting and simultaneously as a fundamental mixer for receiving. In a measured frequency range of 120-160 GHz, a typical output power of 0 dBm is obtained with an input power of +3 dBm. As a fundamental mixer, a conversion gain of -9 dB is obtained at 130 GHz LO, and a noise figure of 19 dB is achieved. The transceiver is successfully demonstrated as a FMCW radar front-end for distance measurement. With a chirp rate of 1.6×1012 Hz/s and a bandwidth of 14.4 GHz, a range resolution of 2.8 cm is demonstrated, and transmission test is shown on different objects.
This paper presents a pre-amplified detector receiver based on a 250 nm InP/InGaAs/InP double heterojunction bipolar transistor (DHBT) process available from the Teledyne scientific. The front end consists of a double slot antenna followed by a five stage low noise amplifier and a detector, all integrated onto the same circuit. Results of measured responsivity and noise are presented. The receiver is characterized through measuring its response to hot (293) and cold (78) K terminations. Measurements of the voltage noise spectrum at the video output of the receiver are presented and can be used to derive the temperature resolution of the receiver for a specific video bandwidth.
The FP7 Research for SME project IMAGINE - a low cost, high performance monolithic passive mm-wave imager
front-end is described in this paper. The main innovation areas for the project are: i) the development of a 94 GHz
radiometer chipset and matching circuits suitable for monolithic integration. The chipset consists of a W-band low noise
amplifier, fabricated using the commercially available OMMIC D007IH GaAs mHEMT process, and a zero bias
resonant interband tunneling diode, fabricated using a patented epi-layer structure that is lattice matched to the same
D007IH process; ii) the development of a 94 GHz antenna adapted for low cost manufacturing methods with
performance suitable for real-time imaging; iii) the development of a low cost liquid crystal polymer PCB build-up
technology with performance suitable for the integration and assembly of a 94 GHz radiometer module; iv) the assembly
of technology demonstrator modules. The results achieved in these areas are presented.
APEX, the Atacama Pathfinder Experiment, is collaboration between Max Planck Institut fur Radioastronomie (MPIfR) with Astronomisches Institut Ruhr Universitat Bochum, Onsala Space Observatory and the European Southern Observatory (ESO). The telescope was supplied by VERTEX Antennentechnik in Duisburg, Germany, and is a 12 m antenna with 15 μm rms surface accuracy operating at the Atacama Desert Llano Chajnantor, in the Chilean Andes at 5100 m altitude. APEX heterodyne single pixel facility receiver are placed in the telescope Nasmyth cabin A. The receivers are coupled to the antenna via relay optics providing possibility to operate either one of the two different PI-type instruments or a multi-channel facility heterodyne receiver to cover 211 - 1500 GHz frequency range. In this report, we present the optical design for APEX single-pixel facility heterodyne receiver providing frequency independent illumination of the secondary for all the receiver channels. We present design of the two-channel facility receiver APEX A, installed and operating since June 2005, and of the coming 6-channel APEX facility receiver. The report includes a brief review of the mixer technology development status for APEX Band 1, 211 - 270 GHz, using sideband separation technology (2SB), Band 2, 270 - 370 GHz, 2SB, Band 3, 385 - 500 GHz, 2SB, and Band T2, 1250 - 1390 GHz, HEB waveguide balanced mixer, those on the development at Onsala Space Observatory. We present description of the receiver control system and example observation of APEX 2a receiver.
The Atacama Pathfinder EXperiment (APEX) is a 12 m antenna operating at the Atacama Desert on the Chilean Andes at about 5000
m altitude. APEX would be equipped with a suit of single-pixel heterodyne receivers covering 211 - 1500 GHz frequency range. We
present here a design of a sideband-separating superconductor-insulator-superconductor (SIS) mixer for the APEX, receiver Band 3,
operating in 385 - 500 GHz band. The receiver uses quadrature scheme with the RF signal passing via a 90-degree waveguide 3 dB
hybrid and the LO is divided by a waveguide E-plane Y-junction. The outputs of the waveguide hybrid are coupled to the mixer SIS
junctions through an E-probe with integrated bias-T. For the LO coupler, conventional branch waveguide couplers are difficult to
manufacture at this high frequency with required accuracy as the branch waveguides become extremely narrow. In order to solve this
problem, we propose an on-chip LO injection, where the LO coupler is integrated onto the mixer chip and fabricated together with the
SIS junction and the tuning circuitry. The on-chip LO coupler is made of superconducting lines, which gives almost a lossless
solution and provides fabrication accuracy better than 0.5 μm by using optical lithography only. Furthermore, the mixer design
includes a novel component, an ellipse termination for the idle LO port, made of thin-film resistive material with sheet resistance
equal to the transmission line characteristic impedance, which gives very broadband performance using extremely compact area.
The Atacama Pathfinder EXperiment (APEX) is a 12 m antenna now operating at the Llano Chajnantor on the Atacama
Desert in Northern Chile at 5100 m altitude. APEX will be equipped with single-pixel heterodyne receivers covering
211 - 1500 GHz frequency range. We present a sideband separation (2SB) mixer using superconducting-insulator-superconductor
(SIS) junction for the APEX band 2, 275-370 GHz. The 2SB mixer is based on a previous development
of a double sideband (DSB) mixer, which is currently installed at the APEX telescope. This DSB receiver has a noise
temperature of about 40-50 K across the band, and, as installed on one of the best site on the Earth, yields total DSB
system noise temperatures of about 100 K for excellent weather.
The 2SB mixer layout uses a modular approach with two identical DSB mixers, independently tested, having similar
characteristics, and combined with an intermediate waveguide block, containing a 3 dB-90° branch-line coupler for the
RF signal and a 3 dB-180° divider for the LO signal. The LO signals are injected into the mixer using a novel
waveguide directional coupler based on 2 quartz chips containing E- probes, allowing to couple -15 dB of the LO to the
RF path. At the conference, we will present the first measurements of this 2SB mixer, together with the current
performance the DSB receiver at the APEX telescope.
APEX, the Atacama Pathfinder Experiment, has been successfully commissioned and is in operation now. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the world's outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of holography. Its surface smoothness of 17-18 μm makes APEX suitable for observations up to 200 μm, through all atmospheric submm windows accessible from the ground.
We present results of the development and measurements of a heterodyne sideband separating SIS mixer for 85-115 GHz band. The sideband separation is achieved by using a quadrature scheme where a local oscillator (LO) pumps two identical mixer junctions with 90° phase difference. A key component in the mixer is a waveguide to microstrip double probe transition used as a power divider to split the input RF signal and to provide transition from waveguide to microstrip line. The double probe transition enables the integration of all mixer components on a single compact substrate. The design also involves coupled lines directional couplers to introduce the LO power to the mixer junctions. An additional pair of SIS junctions is used to provide termination loads for the idle ports of the couplers. Several mixer chips were tested and similar and consistent performance was obtained. The best single sideband noise temperature is below 40 K with IF bandwidth 3.4-4.6 GHz. The sideband suppression ratio is better than 12 dB for both sidebands across the entire RF band. The mixer was also successfully tested with 4-8 GHz IF band. In this paper we present complete mixer characterization data.
Atacama Pathfinder EXperiment (APEX) submillimeter telescope is currently under completion on Chajnator, at an altitude of 5050 m on the Atacama Desert, in the Northern Chile. The telescope facility heterodyne receivers should have 3 bands covering 211-500 GHz. We present design of a 275-370 GHz SIS mixer to be used as a first light APEX Band 2 receiver. A novel waveguide-to-microstrip transition with integrated bias-T is used in this mixer. This structure allows coupling of the RF signal from a full height waveguide to a thin-film superconducting line via E-probe. The wide side of the probe is connected to another port via a specially shaped high impedance line that provides RF/DC isolation. This port is used to extract the IF signal and to inject a DC current that creates a local magnetic field parallel to the plane of the SIS junction to suppress the Josephson effect. The main advantage of this type of Josephson suppression circuit is its compactness as it uses the existing superconducting lines from the SIS integrated tuning circuitry. The entire structure with the probe, SIS junction with its tuning circuitry is placed on a quartz substrate. For more advanced designs, as a sideband separating or balanced mixer that we intend to have for the final version of the APEX telescope heterodyne receiver, the SIS junctions of two balanced or quadrature mixers will be at a very close distance. The standard solution of using superconducting coils to suppress Josephson effect is very difficult to implement and, therefore, this new structure should be of a great advantage.
Single sideband fixed-tuned design, 8 GHz intermediate frequency band per polarization and state-of-art noise performance are the specifications for the SIS mixers to be used for receiver of Atacama Large Millimeter Array (ALMA). A quadrature sideband-separating scheme that uses two identical SIS mixers with the input signal divided equally between the mixers pumped by a local oscillator with 90 degree phase difference, is a good candidate to fulfill these requirements. This side-band separating mixer technology has been successfully demonstrated for mm-wave band. We introduce a new sideband separation mixer aimed for the ALMA instrument, band 7 (275 - 370 GHz). In the design we use a novel fixed-tuned waveguide-to-microstrip double-probe coupler structure that provides a broadband low-loss distribution of the input RF signal between the two quadrature SIS mixers. We present results of HFSS simulations and scale model measurements at 10 and 100 GHz for this key component of the new receiver, the double-probe coupler. The SIS mixers can be placed on the same substrate with their respective integrated tuning circuitry directly coupled to the waveguide via the probes.