The paper presents wave digital models of Wilkinson power
splitters for both equal-split and unequal-split (symmetric
and asymmetric) configurations. Wilkinson-type splitters
are widely used in RF (radio frequency) and microwave
circuits for their matched ports and inherent isolation. By
translating conventional designs into wave digital
frameworks, the proposed models capture power division,
reflection, and isolation characteristics efficiently.
Unequal-split models are demonstrated to handle arbitrary
division ratios while maintaining numerical stability.
Simulation results confirm the accuracy of the wave digital
models compared to standard circuit simulators,
highlighting their potential for rapid analysis,
optimization, and prototyping of multiport RF networks. The
novelty of this work lies in providing a unified wave
digital modeling approach that efficiently represents both
equal and unequal power splits, offering improved
computational efficiency and intuitive insight into energy
flow in complex microwave circuits.

This paper presents an investigation of an integrated
harmonic tag combined with an RF energy harvesting circuit
implemented in microstrip technology. The study considers
both single-tone excitation and dual-tone signals with
frequency offsets of 1 kHz, 1 MHz, and 10 MHz. The proposed
design incorporates two textile patch antennas operating at
2.45 GHz and 4.9 GHz, along with a harmonic tag functioning
at these frequencies. The tag includes a nonlinear element,
specifically a Schottky diode, which enables the generation
of harmonic components. A diplexer is employed to separate
the fundamental frequency from the 2nd harmonic, while the
energy harvesting module utilizes a voltage doubler
rectifier operating at 2.45 GHz. To ensure efficient energy
transfer across the system, impedance matching networks are
carefully designed between the antennas and the harmonic
tag, as well as between the rectifier and the tag. The
performance of the system is evaluated through simulations
carried out in Keysight Advanced Design System (ADS) under
different input power conditions. The obtained results
provide insight into the behavior of both the harmonic tag
and the RF energy harvesting circuit, including metrics
such as generated 2nd harmonic power, harvested DC output,
and overall conversion efficiency.

An experiment with a specially made microwave SIW cavity
sensor was given. The SIW cavity structure consists of a
microstrip tape on a substrate which is then completely
covered with metallization using conductive textile,
without via-holes. The material under test (MUT) area is a
formed rectangular hole in the SIW structure that has only
the bottom metallization. Specific experiments with water
as MUT were tested.

This paper presents an approach based on electromagnetic
(EM) analysis and artificial neural networks (ANN) for the
efficient bandwidth estimation of a planar blade dipole
antenna. The neural model is based on a MultiLayer
Perceptron (MLP) architecture, which relates the antenna’s
geometric parameters, specifically its length and tapering
coefficient, to the lower and upper operating frequency
bounds. The results demonstrate that the proposed MLP model
provides high predictive accuracy with a drastic reduction
in computational time compared to conventional EM
simulations, making it an effective tool for rapid antenna
design.

This paper investigates the impact of the human body on
impedance matching of wearable microstrip antennas under
bending conditions. A cylindrical 3-D Transmission Line
Matrix (TLM) in-house solver with conformal mesh is used
for parametric analysis, enabling accurate modeling of
curved geometries and antenna–body interaction. The study
focuses on separating body-induced effects on reflection
coefficient and resonant frequency from bending
deformation-related mechanisms such as patch elongation,
substrate thickness reduction, and permittivity variation.
Results show that body loading significantly degrades
impedance matching, while bending can partially reduce this
effect by decreasing electromagnetic coupling with tissue.
The proposed approach provides an efficient and physically
consistent framework for predicting antenna performance in
realistic wearable environments.