An irregular tiled array technique is proposed for the application of massive MIMO systems, where the uniformly spaced antenna array elements are irregularly divided into subarrays fed by only one radio frequency (RF) chain separately. As compared to conventional beamforming architecture, the number of RF chains is reduced to one-half or one-quarter of the original number by using domino-shaped subarrays or tetromino-shaped subarrays, respectively. Two beamforming architectures for such a framework are proposed and a minimum mean square error (MMSE) method is applied to design the layouts of irregular arrays efficiently. In the framework of single-user massive MIMO systems, numerical simulation results show that the proposed architectures outperform conventional beamforming architectures and antenna selection architecture under the same number of RF chains conditions. With saving half of the transceivers, the loss of gain of the state-of-the-art sparsely sampled array is 1.9dB in the broadside and 2.2 dB for scanning to 30° in comparison with reference array (i.e., one transceiver per element). By contrast, there is no loss of gain of domino-shaped irregular array (i.e., one transceiver per two elements) in the broadside as compared to reference array and the loss of gain will be about 1.5dB for scanning to 30°.

This paper presents a dual polarized millimeter-wave antenna array, with advantages like compactness, low profile, wideband, wide-scan and low cross-polarization. The concept of tightly coupled dipole arrays (TCDA) is deployed to meet fifth-generation (5G) requirements of wider bandwidth along with low design complexity and compactness. The horizontal dipole arms are positioned above the ground plane and two thin layers of parasitic strips separated by air gap are placed above the dipole arms for better wide-scan impedance. Results for unit cell and 8×8 element array depict voltage standing wave ratio (VSWR) < 3 with impedance bandwidth of 22.6% from 23.5–29.5 GHz. Moreover, array is capable of scan to ±60° in both E and H-Planes. A prototype is fabricated to verify simulation outcomes. The Proposed antenna array can be deployed at base stations in 5G wireless systems.

Bridging the terahertz gap requires synergism between the microwave and photonic communities. Advances in each of these two communities are often complementary but sometimes overlooked. One example is the manipulation of waves, known as anomalous diffraction via the use of metamaterials. This is achieved by controlling the surface impedance of each pixel at the interface of two different materials or alternately the phase and magnitude of the wave diffracted off the pixel. In this paper, a review of developments in wave manipulation from microwave to optical frequencies is presented, together with our new results in the terahertz regime. Generation of phase curves for pixel design requires a priori information on material properties at terahertz frequencies. Fabrication of terahertz devices entails micromachining in the clean room while their experimental validation demands both amplitude and phase information. Through judicial selection of practices in microwave and photonic communities, we can further the exploration of wave phenomena at terahertz frequencies.

Effective downhole-to-surface transmission of the logging signals is one of the critical techniques for logging while drilling (LWD). This letter aims to evaluate an advanced scheme of signal transmission for the LWD proposed by Novatek, with an emphasis on the electromagnetic (EM) coupling between two adjacent pipes and the impedance matching between the coupler and the coaxial cables imbedded in drilling pipes. The numerical modeling of the EM coupling structure has been made by first using the full-wave simulation tool, and then the influence of the parameters of the coupler on the coupling coefficient has been discussed based on circuit simulation software. The optimization of the critical parameters has been made based on the given analysis. It has been found from the analysis that the air gap between the upper and the lower ferrite cores in the coupler is a key factor with remarkable influences on the impedance matching and the coupling coefficient.