The MeerKAT Galaxy Cluster Legacy Survey: I. Survey overview and highlights

Please abstract in the article.The South African Radio Astronomy Observatory (SARAO), the National Research Foundation (NRF), the National Radio Astronomy Observatory, US National Science Foundation, the South African Research Chairs Initiative of the DSI/NRF, the SARAO HCD programme, the South African Research Chairs Initiative of the Department of Science and Innovation.http://www.aanda.orghj2022Physic

Analytical prediction of feed efficiency in offset Gregorian reflector antennas with non planar log-periodic type feeds

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Offset dual-reflector antenna system efficiency predictions including subreflector diffraction

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Wide flare angle axially corrugated conical horn design for a classical offset dual-reflector antenna

This paper outlines the design of a wide flare angle axially corrugated conical horn for a classical offset dual-reflector antenna system. The design minimizes the input reflection coefficient of the horn and maximizes the antenna efficiency of the antenna system by simultaneously limiting the sidelobe and cross-polarization levels to the system specifications. The effects of the number of corrugations in the horn and the number of parameters used in the optimization are also investigated. © 2012 IEEE

Sub-reflector extensions for reduced noise temperature in low-side sub-reflector offset Gregorian systems

This paper describes a simple and low cost method to improve the noise performance of low-noise offset Gregorian antenna systems using a low-side sub-reflector mount configuration. A low-side mount has some logistical and maintenance advantages over the high-side counterpart, since the feed can be accessed without the need for a crane. A simple extension to the bottom of the sub-reflector is proposed which is shown to improve the antenna noise performance over that of the standard high-side mount configuration. © 2012 IEEE

Analytical evaluation of the efficiency improvement of shaped over classical offset dual-reflector antennas including sub-reflector diffraction

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An efficient grid placing technique for 2-D method of moments analysis of coupled line structures

In this paper an analysis routine is presented for a two dimensional method of moments analysis of coupled line structures to find the capacitance matrix. A method is proposed to significantly reduce the number of unknowns. The method borrows from physical optics to predict electrical 'shadows' where the charge density is negligible and can be ignored. This new method is implemented, and a significant improvement in analysis time is achieved with very little loss of accuracy. The analysis routine is used in an optimization loop to synthesize an interdigital filter which displays excellent performance. ©2007 IEEE.Conference Pape

Design of a wideband orthomode transducer

The design of an offset ridge quad-ridged waveguide (QRWG) orthomode transducer (OMT) is presented. By offsetting one of the ridges in the direction of propagation, a much wider single mode operating bandwidth can be achieved than that achievable in a traditional symmetric QRWG OMT's. This wide single mode operating bandwidth ensures that no higher order modes are excited at the feeds of the OMT, which in turn eliminates unwanted resonances often observed in traditional QRWG OMT's. The performance of the OMT is similar to that of traditional types, with reflections below -20 dB and cross coupling below -40 dB across most of the desired 1.7:1 bandwidth. © 2009 IEEE.Conference Pape

Broadband offset quad-ridged waveguide orthomode transducer

The design and measurement of an offset quad-ridge waveguide orthomode transducer (OMT) are presented. The transducer comprises two orthogonal ridges inserted in a square waveguide, with one ridge offset in the propagation direction to greatly increase the singlemode operating bandwidth of the structure. Measurements of an OMT designed to operate across the 2.4-4GHz band show a return loss of better than -20dB for both polarisations and cross-coupling levels of below -40dB over most of the required band. © 2009 The Institution of Engineering and Technology.Articl

Design of a ten-way conical transmission line power Combiner

Axially symmetric power combiners, such as radial line and conical line combiners, are very effective in combining the output signals from a large number of power amplifiers over a wide band with low losses. The main problem with radial lines is the behavior of the characteristic impedance against radial distance, which makes design of radial combiners difficult and normally optimization based. In this paper, a step-by-step design procedure is presented for the design of a conical line combiner. The design strategy relies on the transverse electromagnetic properties of the conical line to eliminate the need for complex full-wave optimization in the design process. Circuit models are instead employed and optimized to achieve a wide matched bandwidth. A ten-way proto-type was developed at X-band, which displayed more than an octave matched bandwidth with low insertion loss. © 2007 IEEE.Articl