A horn-reflector antenna for high-performance submillimetre-wave imaging arrays
International Journal of Infrared and Millimeter Waves 18:2 (1997) 341-358
Abstract:
We have developed an antenna for high-performance submillimetre-wave imaging arrays. The antenna comprises a corrugated horn with an off-axis paraboloidal reflector at its aperture. The corrugated horn is machined directly into two halves of a split aluminium block. This approach avoids electroforming and is compatible with E-plane circuit technology. The resulting antenna is light weight and is ideal for space applications. For compatibility with submillimetre-wave optics, the the behaviour has been calculated by using Gaussian-Hermite modes, and the integrity of the theory has been verified by modelling the behaviour of a 17GHz antenna. The manufacturing procedure has been investigated by machining and testing a horn-reflector antenna for 450-500GHz. Our next step is to extend the technique to 1THz.Analytical expression for the input impedance of a microstrip probe in waveguide
International Journal of Infrared and Millimeter Waves 17:10 (1996) 1685-1705
Abstract:
We present a closed-form expression for the the input impedance of a microstrip probe in a rectangular waveguide. The probe extends only part way across the waveguide and is therefore compatible with RF components that require an open circuit at low frequencies. Our analysis is based on the spectral-domain method and is able to take into account the orientation of the antenna with respect to the direction of propagation. We have examined the validity of our model by carrying out extensive impedance measurements at 5GHz. In those cases where the probe did not extend more than half way across the waveguide, excellent agreement was obtained. We show that the bandwidth of a probe that stretches only part way cross the waveguide is very much greater than the bandwidth of a probe that stretches all of the way across the waveguide and that is earthed at both ends. Moreover, the input resistance is lower and more suited to submillimetre-wave detectors such as SIS tunnel junctions. Our expression suggests that it should be possible to develop low-impedance, wideband probes for nearly double-height waveguide, and this implies that the upper frequency limit to which probes and waveguides can be manufactured can be extended well into the THz frequency range. A related, and often neglected consideration, is that the ohmic loss associated with an oversized waveguide is very much smaller than the ohmic loss associated with a reduced-height waveguide. © 1996 Plenum Publishing Corporation.Loss in normal and superconducting millimetre-wave and submillimetre wave microstrip transmission line
IEE Conference Publication (1996) 149-154
Abstract:
We compare two techniques for calculating the loss of millimetre wave and submillimetre wave microstrip transmission line. The first method is based on conformal transformations and the second method is based on spectral domain analysis. The calculation of loss, through the spectral domain technique, is made possible by removing the current singularities from the path of integration and defining an effective width, based on loss. We use our technique to predict the behaviour of miniature submillimetre wave superconducting microstrip transmission line.A SEARCH FOR PRIMORDIAL ANISOTROPIES IN THE COSMIC MICROWAVE BACKGROUND-RADIATION - FIRST OBSERVATIONS AT 13.5 GHZ WITH THE COSMIC-ANISOTROPY-TELESCOPE
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 274:3 (1995) 861-868
ELECTROMAGNETIC MODELS FOR SUPERCONDUCTING MILLIMETER-WAVE AND SUB-MILLIMETER-WAVE MICROSTRIP TRANSMISSION-LINES
JOURNAL OF PHYSICS D-APPLIED PHYSICS 28:9 (1995) 1983-1991