A comprehensive review of integrated circuit antennas suitable for millimeter and terahertz applications is presented. A great deal of research was done on integrated circuit antennas in the last decade, and many of the problems associated with electrically thick dielectric substrates, such as substrate modes and poor radiation patterns, have been understood and solved. Several antennas, such as the integrated horn antenna, the dielectric-filled parabola, the Fresnel plate antenna, the dual-slot antenna, and the log-periodic and spiral antennas on extended hemispherical lenses, which have resulted in excellent performance at millimeter-wave frequencies, are covered in detail. A review of the efficiency definitions used with planar antennas is included. >

Millimeter-wave and terahertz integrated circuit antennas

Overview of frequency domain measurement techniques of the complex permittivity at microwave frequencies is presented. The methods are divided into two categories: resonant and non-resonant ones. In the first category several methods are discussed such as cavity resonator techniques, dielectric resonator techniques, open resonator techniques and resonators for non-destructive testing. The general theory of measurements of different materials in resonant structures is presented showing mathematical background, sources of uncertainties and theoretical and experimental limits. Methods of measurement of anisotropic materials are presented. In the second category, transmission–reflection techniques are overviewed including transmission line cells as well as free-space techniques.

https://iopscience.iop.org/article/10.1088/0957-0233/17/6/R01/pdf

Frequency domain complex permittivity measurements at microwave frequencies

This review discusses the present state-of-the-art of passive high-power microwave components for applications in microwave systems for RF plasma generation and heating, plasma diagnostics, plasma and microwave materials processing, spectroscopy, communication, radar ranging and imaging, and for drivers of next generation high-field-gradient electron-positron linear colliders. The paper reports on high-power components for overmoded high-power transmission systems such as smooth-wall waveguides, HE/sub 11/ hybrid mode waveguides and quasi-optical TEM/sub 00/ beam waveguides. These include various types of mode converters, polarizers, cross-section tapers, bends, mode selective filters, pulse compressors, DC-breaks, directional couplers, beam combiners and dividers, vacuum windows, and instruments for mode analysis. Problems of ohmic attenuation and unwanted conversion to parasitic modes are discussed in detail and rules for alignment requirements are given. In the case of waveguide transmission, this review mainly concentrates on circular waveguide components but also deals with rectangular waveguide.

Passive high-power microwave components

In previous work, we have described novel smooth-walled multiple flare-angle horns designed using a genetic algorithm. A key feature of these horns is that they can be manufactured very rapidly and cheaply in large numbers, by repeated direct drilling into a single plate of aluminum using a shaped machine tool. The rapid manufacturing technique will enable the construction of very low cost focal-plane arrays, offering an alternative to conventional electroformed corrugated horn arrays. In order to experimentally demonstrate the new technology, we constructed a 230 GHz focal-plane array comprising 37 smooth- walled horns fabricated by direct drilling. We present the measured beam patterns for a large sample of these horns across the array, demonstrating the suitability of our manufacturing techniques for large format arrays. We have measured the cross coupling between adjacent feeds and have shown that it is negligible. We also present high quality beam patterns measured for a much smaller 700 GHz horn, showing the promise of the extending this technology to THz frequencies.

Experimental Investigation of a Low-Cost, High Performance Focal-Plane Horn Array

Silicon platelet corrugated feedhorn arrays for cosmic microwave background (CMB) measurements at millimeter wavelengths (130 GHz to 170 GHz) have been developed for deployment for the polarization-sensitive upgrade to both the Atacama Cosmology Telescope (ACTpol) and the South Pole Telescope (SPTpol). We present fabrication developments and the first results of a prototype monolithic feedhorn array consisting of 84 horns. Measurements at room temperature show good beam quality across the needed bandwidth, return loss of <−20 dB, an insertion loss of <−0.4 dB, and cross polarization of <−23 dB. The 32 platelets were aligned to a 1σ variation of 8 μm.

An 84 Pixel All-Silicon Corrugated Feedhorn for CMB Measurements

Corrugated horns are widely used and highly efficient, especially in their use as feeds for microwave reflector antennas. This book is devoted to the theory and design of corrugated horns and scalar feeds and explains why hybrid mode feeds are ideal feeds for reflectors.

Corrugated Horns for Microwave Antennas

The design principles used to realize smoothly profiled corrugated horns are described. The smooth profiling causes power to be converted to higher order HE/sub 12/ modes which radiate to produce high sidelobes in the copolarization patterns. A computer-aided spherical modal-matching technique is used to study the higher-order mode conversion. The results show good agreement with measurements. A profiled horn using a series of discrete conical sections is proposed to eliminate most of the mode conversion. A horn designed in this way is presented and shown to possess improved performance characteristics in comparison to a smoothly profiled design. >

Design of profiled corrugated horns

Profiled dielectric loaded horns are investigated with the aim of obtaining low peak crosspolar level and high aperture efficiency. A number of nonlinear profiles are considered. The paper also looks into the influence of profiling on the bandwidth of the horn and the effect of nonuniformities in the dielectric material on horn performance.

Design and performance of profiled dielectric-loaded horns

The dielectric cone loaded horn consists of a central cone of solid or foam dielectric supported by a second dielectric with a metallised outer layer. The horn has low cross-polarisation over a wide bandwidth and the absence of flanges means better utilisation of the aperture area. The dielectric gives an additional method of controlling the fields in the horn. The authors investigates dielectric loaded horns with a shaped profile. They show that the profiled dielectric horn gives useful control over the performance of the horn. It can be designed in two distinct ways. Either the length of the horn can be kept the same as a linear tapered horn which will give improved electrical performance, or the length (and weight) of the horn can be reduced by comparison with the linear horn, whilst maintaining similar low levels of cross-polarisation.

A. D. Olver

Papers

Corrugated Horns for Microwave Antennas

Design of profiled corrugated horns

Design and performance of profiled dielectric-loaded horns

Profiled dielectric loaded horns