In this letter, an X-band reflection-type phase shifter is presented. It is based on a single-layer stub-loaded coupled-line coupler loaded by two-varactor tuning circuits. This choice of coupler significantly improves on the phase shifter bandwidth achievable with a branch-line coupler, as it features a lower phase imbalance across the band of interest. The proof-of-concept prototype achieves better than 10-dB return loss across a 20% fractional bandwidth. The phase shifter further exhibits insertion loss of 2.1 ± 1.3 dB and maximum phase shift of 392° at 10 GHz, leading to a state-of-the-art figure of merit at X-band of 115°/dB. The occupied area is 0.25λg².

Oscillation-based testing of analogue electronic filters removes the need for test signal synthesis. Parametric faults in the presence of normal component tolerance variation are challenging to detect and diagnose. This study demonstrates the suitability of statistical learning and deep learning techniques for parametric fault diagnosis and detection by investigating several time-series classification techniques. Traditional harmonic analysis is used as a baseline for an in-depth comparison. Eight standard classification techniques are applied and compared. Deep learning approaches, which classify the time-series signals directly, are shown to benefit from the oscillator startup region for feature extraction. Global average pooling in the convolutional neural networks (CNN) allows for Class Activation Maps (CAM). This enables interpreting the time-series signal’s discriminative regions and confirming the importance of the start-up oscillation signal. The deep learning approach outperforms the harmonic analysis approach on simulated data by an average of 11.77% in classification accuracy for the three parametric fault magnitudes considered in this work.

Dielectric printed and plated waveguide components offer cost and weight benefits over metal printed equivalents, with silver plating using Tollens reagents holding significant advantages over electroplating. This work extends on previous demonstrations of this process in plating stereolithography (SLA) printed resin waveguide parts by investigating number of plating rounds, reaction temperature and plastic base. It is found that less than 1.5 dB/m attenuation is achievable in WR42 waveguide using white SLA plastic and silver plating, comparing favourably with the 10 dB/m achieved by printing the same part using Ti64 powder bed fusion. This process improvement is further demonstrated using waveguide power dividers, slow-wave delay sections and rectangular horn antennas.

A compact high‐power broadband absorptive filter is designed by cascading a slotted waveguide harmonic pad with a wide stop‐band reflective filter. Absorption is achieved by coupling a surface current standing wave to absorptive external auxiliary waveguides through a cascade of transversal broadwall slots in rectangular waveguide.

Gigahertz transverse electromagnetic (GTEM) cells are used extensively in industry for testing the impact of defined E-fields on devices sensitive to electromagnetic interference. Compared to anechoic chambers, GTEM cells are small, inexpensive and require less powerful amplifiers to achieve the same field strength. This paper presents the design, simulation and qualification of a compact GTEM cell capable of generating field strengths in excess of 600 V/m over a 20 × 20 × 15 cm test cavity, whilst being less than 2.2 × 1.3 × 1 m in total size. Specific hybrid FEM-MLFMM simulation strategies are provided to examine high power device characteristics prior to manufacturing, including accurate modelling of absorber materials. Practical notes on manufacturing and qualification are also presented.

Analog signal processing (ASP) is a promising alternative to DSP techniques in millimeter-wave (mm-wave) technologies such as 5G, with the second-order all-pass networks a key building block in ASPs. We present an active on-chip mm-wave second-order all-pass network in a 130-nm, 280-GHz f _max SiGe BiCMOS process with an effective bandwidth of 40 GHz, peak delay of 62 ps at 36 GHz, delay Q _D value of 3.6, and a magnitude ripple of 1.4 dB. A layout-focused design methodology incorporating layout parasitics and process tolerances is followed. This is the first reported mm-wave bandwidth second-order all-pass network and the first monolithic microwave integrated all-pass network with a Q _D value greater than 1.