In this work, a novel design of patch antenna with two symmetrical slits and two closely spaced resonances is proposed. Novel patch antenna demonstrates a great flexibility in impedances adjustment at both resonances that is of a great importance in the design of series fed antenna arrays with a large number of radiating elements. Printed antenna with two linear arrays consisting of 16 serially fed patches is designed and fabricated. Measured results agree very well with simulations. Antenna operation frequency range is 15.6–17.3 GHz that is 10.3% of a relative bandwidth. The measured antenna gain is 19.5 dBi with a small variation of 1.2 dB within the whole operating bandwidth, sidelobe levels are below −22 dB in H-plane and −11.5 dB in E-plane. Half power beamwidth is less than 8° and 40°, in H-and E-planes, respectively. Antenna array exhibits the enhanced impedance and radiation bandwidth in comparison with similar antenna structures and is very suitable for various radar applications, notably for compact, low-cost frequency-modulated continuous wave systems.

A new geometry for uniplanar, ultra-wideband monopole antenna has been proposed for operations in the 1.8–30 GHz band, thanks to its fractal structure in the form of a cardioid. The antenna has extremely small dimensions at 0.21$\lambda$ × 0.285$\lambda$ at the lowest frequency of 1.8 GHz. A parametric analysis of the influence of certain antenna dimensions on its characteristics was performed in order to achieve the widest possible impedance bandwidth. This antenna is designed for low-cost FR-4 substrate because it is primarily intended for use in broadband energy harvesting and IoT systems, but it is also suitable for applications in communication systems. Simulation results show that the antenna has a reflection coefficient $\left(S_{11}\right)$ below −10 dB in the entire 1.8 GHz to 30 GHz frequency range, which covers all existing cellular bands: 3G, 4G, 5G Wi-Fi, ISM, satellite communication and radar bands. The antenna exhibits gains up to 5 dBi.

In this paper, the S-parameters of SMS 7630 zerobias Schottky diode are modeled with artificial neural network (ANN). A single network is trained with the data obtained from the measurements using a vector network analyzer. The frequency band of those measurements is 0.5 – 5 GHz, and input power is ranging from-25 dBm to 5 dBm. The learning and generalization capabilities of the developed ANN were tested, and results turned up to be satisfactory and useful, especially considering a limited number of different input powers for network training.

This paper is intended to draw attention to underutilized principle of multiphase feeding structures of circular polarized (CP) printed antennas, and especially advantages of using tree phase feeding structures over the more conventional quadrature feeds, like increasing axial ratio (AR) bandwidth. This is done by constructing simple tri-pole radial slot antenna and feeding it by a phasing structure derived from a cross between double-Y baluns and the theory of 3-phase static phase converters.

Baluns have been studied for several decades. They have been used in antennas as unbalanced-to- balanced signal convertors and have sometimes taken on the role of impedance transformers. Apart from their use in antennas, baluns can be found across a variety of applications, ranging from mixers and samplers to power dividers and amplifiers. Good reviews of the most common balun types can be found in [1]–[3].