Analysis of Probes in a Rectangular Waveguide

Yeap, Kim Ho; Tham, Choy Yoong; Nisar, Humaira; Loh, Siu Hong

doi:10.1515/freq-2012-0117

Cited by 8 publications

(2 citation statements)

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“…Signals at terahertz frequencies quite often are from distant sources resulting in the signals at extremely low orders of magnitude [4]. Standard metallic waveguides may exhibit signal attenuation at levels unacceptable for such applications [5].…”

Section: Introductionmentioning

confidence: 99%

Attenuation in Superconducting Rectangular Waveguides

et al. 2015

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We present an accurate analysis on the attenuation of waves, propagating in rectangular waveguides with superconducting walls. The wavenumbers k x and k y in the x and y directions, respectively, are first obtained as roots of a set of transcendental equations developed by matching the tangential fields at the surface of the wall with the electrical properties of the wall material. The complex conductivity of the superconducting waveguide is obtained from the extended Mattis-Bardeen theory. The propagation constant k z is found by substituting the values of k x and k y into the dispersion relation. We have computed and compared the loss in the waveguides below and above the critical temperature. At frequencies above the cutoff frequency f c but below the gap frequency f g , the loss in the superconducting waveguide is significantly lower than that in a normal conducting waveguide. Above the gap frequency, however, the result indicates that the attenuation in the waveguide below the critical temperature is higher than that at room temperature. We attribute the higher loss as due to the higher surface resistance and field penetration for superconducting waveguides operating above the gap frequency.

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Section: Introductionmentioning

confidence: 99%

Attenuation in Superconducting Rectangular Waveguides

et al. 2015

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“…Incoming signal radiation is collected by both the primary and sub-reflectors and is subsequently focused onto a sensitive receiver located behind or at the bottom of the parabolic reflector. The incoming waves are then converted into electrical signals inside the receiver and processed to display the spectral and spatial information carried by the signal [6]- [8].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Offset Antennas in Radio Telescopes

Yeap

Yiam

Lai

et al. 2016

International Journal on Advanced Science, Engineering and Information Technology

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We present an analysis on the performance of two popular dual offset antennas design, i.e. the offset Cassegrain and Gregorian reflector antennas. In our study, we have adopted the design parameters for the Cassegrain configuration used in the Atacama Large Milimeter Array (ALMA) project. Modifications on the original parameters are made so as to meet the design requirement of the offset configurations. To reduce spillover loss, we have adjusted the angle between the axis of the primary reflector and that of the sub-reflector to 0.20 o. The results obtained from the physical optics computation show that the amplitude at the main lobe of the Gregorian configuration is approximately 74.02 dB, while that of the Cassegrain configuration is approximately 74 dB. The maximum (relative) side lobe level, SLL dB for the Cassegrain and Gregorian configurations are found as-3.67 dB and-3.69 dB respectively. Although the magnitude of the main lobe for both configurations is comparable, the Gregorian antenna gives relatively lower SLL dB. In other words, the Gregorian configuration performs relatively better than its Cassegrainian counterpart.

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