A waveguide fed transverse slot has been analysed using the Method of Moments (MoM) formulation, wherein the internal admittance matrix elements have been evaluated from image theory and using the images of the slot due to waveguide walls. The contribution from all the images not in the same row as the slot has been evaluated using a closed-form expression and a rapidly converging series with negligible contribution. The contribution from the row containing the reference slot has been evaluated by adding the mutual admittance between a few images and the reference slot using some recently developed simple and accurate approximations. The formulation has been extended to transverse slots radiating between the baffles. The results calculated using this simple, efficient and intuitive method are in excellent agreement with other theoretical as well as measured results. The technique can be extended to other slot configurations such as an inclined slot and for other slot aperture distributions such as with an edge condition in configurations permitting image formation.

The time-domain simultaneous signal and noise analysis of mm-wave/THz devices (diode) modelled as a transmission line is considered. For such devices, stochastic telegrapher's equations of a transmission line are extracted assuming a quasi-transverse electromagnetic mode. Since the analytical solution for these equations does not exist, numerical analysis of such equations is presented here in millimetre-wave and terahertz frequencies. These equations are analysed with two different numerical methods in the time domain, namely the finite-integration technique and the Method of Moments. A semi-distributed model in the ADS commercial software is used to validate the numerical results. Non-linear effects in the model are introduced to simulate a Schottky diode. Using this non-linear model signal and noise behaviour in a Schottky diode is analysed, resulting in the simulation of the noise figure of the device.

This article proposes a simple method of designing a highly efficient wideband parallel-circuit (PC) class-E/F₃ power amplifiers (PAs). A combination of the double-reactance compensation technique and fundamental as well as third-harmonic series-tuned resonators is used for the design of the PC class-E/F₃ PA output matching network. The step-by-step design flow and corresponding equations to calculate each component's value are also presented. Based on this method, the simulated optimal impedances of the reactance compensation network present almost a constant over the desired band, which satisfies the requirement of the wideband performance. Measured results reveal that using a GaN high electron mobility transistor (HEMT), the fabricated PA demonstrates the measured drain efficiencies of 60.1–80.5%, as well as output powers of 36.0–40.9 dBm from 350 to 730 MHz (fractional bandwidth = 70.4%).

Guided modes excited by a current source in a multilayer cylindrical structure is thoroughly investigated. The guidance condition in the multilayer structure is formulated. Based on this, three antenna configurations in cylindrical stratified media that are of strong practical interest are rigorously investigated: viz. a monopole antenna, a conformal axially-directed slot antenna and an azimuthal slot antenna in a cylindrical layered medium. While previous treatments of such configurations did not investigate the mode-excitation problem of antennas in stratified cylindrical media and were limited in their applicability for a dipole antenna in a cylindrical medium or assumed the slot-current distribution for a slot antenna over a conducting cylinder only, the current investigation provides an in-depth and rigorous insight to the modes excited and power coupled to the excited modes for the antenna configurations and removes such restrictions. In addition to the efficient and rigorous investigation of the coupling problem for the three antenna structures, the radiation characteristics of the antenna configurations are also evaluated using the method of stationary phase, enabling a comprehensive treatment of the antenna structures from both the coupling and radiation aspects.

This study presents the implementation of a waffle-iron filter in multi-layered substrate integrated waveguide technology, together with an approximate technique for measuring the stop-band scattering parameters of such a multi-mode waveguide filter. Two filters are designed for different stop-band widths, and tested. Two measurement techniques are presented – one utilising a set of measurements with different probe positions, and one using a radiating horn. Measured results for the two prototypes, show better than 12 dB pass-band return loss over 8.5–10.5 GHz for both, with stop-band attenuation in excess of 70 dB over the harmonic bands 15–43 GHz for one and 15–48 GHz for the other.