A new type of slow-wave EBG microstrip rat-race hybrid ring is presented. It effectively reduces the occupied area to 11% of the conventional rat-race hybrid ring. It does not need any impedance transformers on the ports.

The 3D printing parameters are known to have a significant impact on manufactured parts, and the layered morphology of these parts makes mechanical design analysis for engineering applications difficult. In this work, the tensile strengths and microhardness of 3D printed polylactic acid (PLA) specimens with different orientations and numbers of individual layers of mesh material (polyvinyl chloride – PVC) were investigated as a laminate composite. Composite specimens were obtained using 3D printing via fused deposition modelling (FDM). Moreover, the influence of printing parameters (i.e. infill density and layer height) and the number and orientation of reinforced meshes on the mechanical response was investigated. Fracture strength of PLA/PVC laminate composites ranges from 31.30 MPa (3 PVC mesh layers; mesh height position: 25 %│50 %│75 %; infill density: 60 %; PVC mesh orientation: 90°│45°│90°; layer height: 0.2 mm) to 18.62 MPa (without PVC mesh; infill density: 30 %; layer height: 0.1 mm) demonstrating a significant impact of the number of the PVC mesh layers, infill density of PLA and layer height on the final mechanical parameters of printing PLA/PVC elements. The surface hardness at the micro load level showed that the number of reinforcement layers affects the microhardness value, as well as material filling and mesh orientation. The specimen with the following parameters gave the best results: layer height: 0.2 mm; 3 PVC mesh layers; infill density: 60 %; PVC mesh orientation: 90°│45°│90°. The average hardness values for one layer and three layers of mesh were in accordance with tensile test results.

A basic overview of electronics on textiles is given with an emphasis on self-adhesive conductive materials and their characteristics. It is kept on materials, self-adhesive conductive textiles and metal tapes and foils, which can be easily obtained. Their advantages compared to other techniques for electronics on textiles are described. The proposed structure is for the microwave area, which is a demanding area with regard to high frequencies.

A printed antenna array consisting of 10 wideband symmetrical pentagonal dipoles is presented. The feed network of impedance transformers is employed to provide appropriate amplitude and phase distribution necessary to obtain flat top beam pattern. The measured results demonstrate excellent radiation characteristics including 38° flat gain region with maximum ripple of 3.5 dB at the centre frequency. Furthermore, the proposed antenna that is placed in corner reflector with angle of 60° has good gain (17 dBi) and side lobe suppression (18.9 dB). Although it is designed at the centre frequencyf_c=12 GHz, it was shown to be capable of shaping a good flat top radiation pattern within a fractional bandwidth at least 6 % of centre frequency. Also, proposed antenna features cheap, simple and easy fabrication that makes it suitable for mass production.

A new type of microwave position sensor is introduced. It is a microstrip stub resonator with slotted ground plane under the stub. It produces frequency-modulated signal with frequency corresponding to covering of the slot in the ground plane. The sensing is performed by sliding the metal plate over the slot. The structure is simple, low fabrication cost and compact. It is without multilayers, coupling, via holes, air bridges, active or discrete components.

Novel design of low-pass microwave filters based on cascading of identical unit cells is proposed. Dispersion relation is used to determine the cell parameters for a given relative stop-band width. For a filter consisting of two cells, each made of single- or two-section transmission lines, the design formulas and curves are presented. Based on them typical filters are designed, fabricated, and measured. The presented filters feature a deep stop band and a wide rejection band, which can be controlled within the proposed design procedure. The design procedure and the simulation results are verified experimentally by measurement of the fabricated structures containing two and three cells.