Uncooled Receivers Research Articles

HIGH-EFFICIENCY INFRARED RECEIVER

Recent research and development show promising use of high-performance solid-state receivers of the electromagnetic radiation. These receivers are based on the low-barrier Schottky diodes. The approach to the design of the receivers on the basis of delta-doped low-barrier Schottky diodes with beam leads without bias is especially actively developing because for uncooled receivers of the microwave radiation these diodes have virtually no competition. The purpose of this work is to improve the main parameters and characteristics that determine the practical relevance of the receivers of mid-infrared electromagnetic radiation at the operating room temperature by modifying the electrodes configuration of the diode and optimizing the distance between them. Proposed original design solution of the integrated receiver of mid-infrared radiation on the basis of the low-barrier Schottky diodes with beam leads allows to effectively adjust its main parameters and characteristics. Simulation of the electromagnetic characteristics of the proposed receiver by using the software package HFSS with the basic algorithm of a finite element method which implemented to calculate the behavior of electromagnetic fields on an arbitrary geometry with a predetermined material properties have shown that when the inner parts of the electrodes of the low-barrier Schottky diode is performed in the concentric elliptical convex-concave shape, it can be reduce the reflection losses to -57.75 dB and the standing wave ratio to 1.003 while increasing the directivity up to 23 at a wavelength of 6.09 μm. At this time, the rounded radii of the inner parts of the anode and cathode electrodes are equal 212 nm and 318 nm respectively and the gap setting between them is 106 nm. These parameters will improve the efficiency of the developed infrared optical-promising and electronic equipment for various purposes intended for work in the mid-infrared wavelength range.

A terahertz receiver based on electromagnetic materials

It is shown that the detector and antenna parts of an uncooled terahertz receiver based on submillimeter and nanometer resonance structures in the form of spiral fragments and microresonators in the form of round holes enable one to obtain a reflection loss of -24.29 dB, a standing-wave ratio of 1.13 and a conversion efficiency of 99.63%. The wide range of potential possibilities of the practical use of terahertz radiation is due to the fact that the individ- ual frequencies of molecules of any material lie precisely in the gap between the radio-frequency and optical bands. For prac- tical applications of terahertz technology, highly sensitive, simple, reliable and cheap radiation receivers are required. Recently, ways of constructing such receivers based on artificial media, belonging to the class of composite metamaterials, have been actively investigated. These electromagnetic materials, which contain elements of special form with dimensions that are small compared with the wavelength of the electromagnetic radiation and which are capable of exciting electric cur- rents, possess unique electrical, radio and optical properties, not possessed by natural materials. These properties depend on the resonance interaction of an electromagnetic wave with a heterogeneous medium, consisting of a mass of artificial reso- nance elements, which sense the radiation as a continuous electromagnetic medium (1-4). The purpose of this paper is to develop and investigate one of the possible ways of constructing an integrated uncooled terahertz receiver, the detector and antenna parts of which are based on submillimeter and nanometer resonance structures in the form of spiral fragments and microresonators in the form of round holes. The constructional form of the proposed integrated uncooled receiver is shown in Fig. 1. Arrays of left spiral frag- ments 2 and right spiral fragments 7 are formed directly on a substrate 1 in a strict geometrical order, along the trajectory of a log-periodic spiral. Output leads 3 are constructed in the form of a two-arm Archimedes spiral. An absorber 4 contains microresonators 6 - four circular fragments - and are situated on heat-sensitive element 5, along the perimeter of which the spiral fragments 2 and 7 are arranged in a certain order. We used the Ansoft HFSS v. 12 software for a computer investigation of the expected fundamental parameters and characteristics of the terahertz radiation receiver. The numerical package of three-dimensional electrodynamic modeling for solving Maxwell's equations is based on the finite element method with tetrahedral subdivision of the model, which enables the electromagnetic field distribution to be calculated and is a reliable instrument for developing highly effective components (5, 6). Each element of the subdivision grid can be made separately from any material of the database, which provides the possibility of analyzing complex structures with different electrodynamic parameters. A numerical calculation of the integrated uncooled receiver was carried out taking the boundary conditions into account, namely, no reflected waves in a limited volume of open space and an input electromagnetic radiation power of 1 mW. The source of electromagnetic radiation was a wave port, placed parallel to the plane of the receiver. The minimum distance

A new compact microwave spectroradiometer-ozonometer

A new-generation mobile microwave spectroradiometer intended for studying the Earth’s ozone layer is described. The device receives thermal radio-frequency emission of the stratospheric ozone at the frequency of its rotational transition (110 836 MHz) in a 240-MHz frequency band. The spectral resolution at the O3 line center is 1 MHz. The effective noise temperature of the uncooled receiver in the single-sideband mode is ∼2000 K. The ozonometer is equipped with a computer-aided data measurement, calibration, and preprocessing control system. The device is intended to obtain an ozone profile in a 20- to 60-km altitude interval within 15–20 min.

ALOFT: A Potential Low Frequency Space VLBI Mission

We present a preliminary study of A LOw Frequency Orbiting Telescope (ALOFT) which co-observes with ground radio telescopes, in a similar fashion to the current VSOP mission. Our current straw-man ALOFT mission has a spacecraft operating at three frequency bands (0.33, 0.6, and 1.4—1.6 GHz) in an orbit with a 10,000 km apogee height. It should be relatively low cost as the lower frequencies less stringently constrain the design, for example uncooled receivers, narrower bandwidth, and simple antennae. The major science goal to be addressed by this mission is to examine scattering phenomena through the technique of space VLBI, although other problems, such as AGN physics, can of course also be addressed.

Uncooled receivers for CO2 laser radiation

This article summarizes the data on low-inertia uncooled singleelement and matrix type radiation receivers for CO/sub 2/ laser radiation that have a high degree of reliability and are immune from interference from various external sources. The RR are based on the use of various effects produced when radiation interacts with matter, so that their classification can be quite arbitrary. The effects on which RR can be based, and the customary names of the detectors are listed: the hot-electron bolometer, Putley detector, carrier drag effect, photoemission and IR photon counters. Thermal receivers are examined including bolometers, thermocouples, optacoustic receivers and pyroelectric receivers.