This letter discusses the design of a dual-polarized four-element linear antenna array with increased port-to-port isolation, intended for base stations of single-channel full-duplex systems. The antenna is designed for the U-NII 5.15—5.925 GHz frequency band and is characterized by port-to-port isolation higher than 57 dB and cross-polarization better than -27 dB within the main lobe. An electromagnetically-coupled microstrip antenna was used as a single element of the antenna array. Enhanced isolation was obtained owing to the multi-layer antenna structure and special feeding network utilizing the pairwise anti-phased feeding technique combined with a careful selection of phase-shifters and power dividers. The antenna parameters were optimized with the use of full-wave simulations, while the scattering parameters and radiation characteristics were verified by measurements.

In this letter, a CUDA-enabled graphics processing unit (GPU) accelerated implementation of the method of moments (MoM) for electromagnetic simulation of wire-grid models of arbitrary configurations of conducting surfaces and wires is presented. The solution based on the frequency-domain electric field integral equation (EFIE) discretized using piecewise-linear (triangular) functions for expansion and testing is considered. Some issues pertinent to porting a single-CPU sequential code to an inherently parallel GPU platform are addressed. The GPU numerical results for a user-created benchmark structure are backed up with comparison to CPU results. A noticeable speedup (about 6×) of the overall MoM simulation is achieved due to employing GPU.

In this letter, a CUDA-enabled graphics processing unit (GPU)-accelerated implementation of the method of moments (MoM) for solving three-dimensional conducting body-wire problems is presented. The solution is based on the mixed potential integral equation (MPIE) discretized using Rao-Wilton-Glisson (RWG) basis functions. The CUDA environment is employed to port a single-CPU sequential code to the parallel GPU platform, and some relevant issues are discussed. Numerical results are given for a helical antenna with a cylindrical cup reflector. The measured speedup of about eight times over the CPU implementation is demonstrated.

In this paper, a modified triple-tuned microstrip bandpass filter is presented. The filter consists of inductively cross-coupled resonators tuned with varactors. The application of the additional source-load couplings together with resonator branch swapping results in two transmission zeros tuned concurrently with operating frequency. These transmission zeros placed on both sides of the passband significantly increase slope steepness in transition bands. The example filter tuned from 0.36 to 0.78 GHz and controlled by a single voltage was manufactured and validated by measurements. It has a constant fractional bandwidth of 11%, low in-band insertion loss ranging from 1.8 to 2.5 dB, and out-of-band attenuation up to 5 GHz without parasitic passbands. The obtained filter parameters made it useful for preselector networks.

This article presents a novel compact widely tunable bandpass filter. The filter consists of two resonators that are double-coupled, inductively, where the coupling inductances are elements of the input and output networks. The application of double-coupling enabled the transmission zero next to the upper cutoff frequency. This makes the filter useful for applications in preselector networks used in receiving systems with a low to intermediate frequency with the desired channel frequency lower than the image channel frequency. The article shows the practical realisation of the varactor-tuned example filter fabricated as a microstrip planar network of an overall size of 0.03${\lambda }_g$ × 0.045${\lambda }_g$. The tuning range of the proposed filter is from 410 MHz to 880 MHz with the fractional bandwidth equal to 7.5–8.1% and an in-band insertion loss better than −3.4 dB. The achieved IP3 value exceeds 17.5 dBm.