A microwave pulse compressor (MPC) system formed by an inductive iris, a straight rectangular waveguide, and an H-plane T-junction is experimentally studied. The MPC design, which is based on an equivalent circuit simulation model, ensures the optimum cavity-storage gain at 1.3 GHz. A low-pressure gas discharge tube (GDT) that is placed at the side arm of the T-junction implements the switching trigger for the cavity energy extraction. The experimental results show that high pulse repetition frequency (PRF) operation together with optimal cavity-extraction gain is feasible by carefully selecting the GDT gas type, pressure level, and flow rate. Under optimal conditions, the MPC system approaches the theoretically predicted cavity-extraction gain of 19 dB and a PRF up to 300 Hz.

Wearable electronics have evolved from electronic components secured on the human body with straps and belts to partial electronic components integration onto textile structures. Cables and standard components defeat the purpose of the wearable approach by being bulky, rigid and especially not being able to withstand standard textile cleaning/care methods (washing, dry-cleaning, etc.). New 3D textile structures can provide a promising solution. In this research project, we examined the capacitive behaviour of specially prepared 3D weft knitted textile fabrics. The samples knitted specially for this project incorporated conductive outer layers and an insulating inner layer. The outer layers form the plates of the capacitor and the insulating layer plays a role of the dielectric material between the two plates. The structure of these 3D knits allows for inherent capacitive behaviour of the material. These 3D weft-knitted fabrics can be produced on usual existing knitting machines, without any need of dedicated, specialized or expensive equipment. The expected values of the capacitance, based on theoretical calculations, satisfactorily approach the values derived from the measuring process. The ability to customize the structure and hence the capacitance of the 3D fabrics-based capacitors is a positive point towards the design of the textile-based electronics systems in the future. Therefore, the development of textile capacitors based on the 3D fabrics is expected to be an essential contribution to the integration of the wearable system concept.

A microwave pulse compressor (MPC) consisting of an iris, a straight waveguide section, and a T-junction can be used in order to convert a long pulse with lower power to a shorter pulse with a higher power. A significant compression gain can be achieved, provided that the system is designed precisely. The duration of the compressed pulse is proportional to the cavity length, thus imposing a constraint on the development of mobile systems. In this work, we present the circuit/transmission-line-based design methodology that we follow in order to fold the cavity (while retaining the same electrical length) by using T-junction turns. For example, we design a 1.3-GHz folded compressor and compare its performance to the corresponding one of a straight-cavity compressor. The 3-D full-wave simulations with CST Studio Suite and experimental measurements with the developed compressor confirm the accuracy of the proposed design methodology.

A new method for the analysis and design of fiber Bragg gratings (FBGs) based on the theory of transmission lines has been developed and verified both theoretically and experimentally. The method is an extension of the coupled-mode theory and utilizes the equivalent transmission lines in order to simulate any type of grating, with an easy and direct implementation. The method provides the ability to analyze the optical devices without using full wave approaches, while also facilitating the incorporation of core materials with a complex or non-linear refractive index, non-uniform distributions of the grating’s refractive index, and tilted and phase-shifted gratings. The approach also allows the design of the grating for a given reflection spectra. Numerical results of the method’s application on a randomly varied inscription of the refractive index of a FBG have also been simulated and discussed. Using this method, the characteristics of an erbium-doped (ED)-FBG have been simulated and the predictions verified experimentally.

Microwave pulse compression systems using a waveguide cavity composed by an inductive iris and an H-plane T-junction with the primary arm shorted is studied using the individual components' equivalent circuits. The equivalent circuit model of the device is studied in detail and optimized design characteristics and performance figures such as the length of the waveguide cavity, the iris width, the length of the shorted arm as well as the cavity gain and leakage are calculated using closed form expressions. Based on the aforementioned analysis, an optimized design procedure is proposed. As a verification of the proposed method, a microwave pulse compressor working at 1.3 GHz is studied and then compared with the results of a full-wave three dimensional commercial electromagnetic code.

Automobiles are incorporating a vast number of automated electronic subsystems that control critical car functionalities related to safety, performance, and driving assistance. Electromagnetic compatibility is safeguarded by manufacturers but at the same time, these electronics offer a means of susceptibility to directed electromagnetic energy launched by law enforcement units aiming at controlling a car at a distance. In this article, we present the results of an experiments campaign evaluating the vulnerability of a car engine control and selected parts to intentional electromagnetic interference. Frequency bands of increased susceptibility are identified in order to minimize the impinging pulsed field's power, duty cycle, and number of pulses. The effect of car body electromagnetic attenuation is assessed and guidelines are given regarding the safety of passengers from both radiation and unexpected car behavior.