Efficient Numerical Analysis of a Periodic Structure of Multistate Unit Cells

Application of the synthetic function expansion (SFX) algorithm to the analysis of active 1- and 2D periodic structures is presented. The single unit cell consisting of a microstrip line loaded by patches positioned below the line is turned into an active structure by inserting a pair of 2 switches to the two ends of each patch; the states of the pair of switches are changed contemporaneously. Variation of the states of the switches modifies the current distribution on the structure. The tunable multistate unit cell is arranged in 24-, 120-, and 9 × 24 element configurations and numerically analyzed. The computational complexity required for the characterization of the large number of possible configurations is lightened by the use of the proposed numerical method

Darkening Low-Earth Orbit Satellite Constellations: A Review

The proliferation of low-earth orbit (LEO) satellites and the LEO satellite internet will be a game-changer for the low-latency high-speed global internet. While this new generation of the satellite internet in conjunction with fifth generation network (5G) and sixth generation network (6G) enabled emerging technologies, such as precision farming and smart cities, it will bring new challenges, such as satellite collision, limited satellite lifespan, security concerns, and satellite brightness. This article discusses the satellite brightness caused by LEO constellations that potentially affect the ongoing astronomical studies. It reviews the underlying contributors to the satellite brightness as well as the state-of-the-art technologies proposed to mitigate this emerging challenge.This work was supported in part by Macquarie University; in part by the Australian Research Council Discovery Grants Scheme; and in part by the Faculty of Engineering and Information Technology, University of Technology Sydney, Seed Grant

IEEE Access Special Section Editorial: Bio-Compatible Devices and Bio-Electromagnetics for Bio-Medical Applications

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Mutual Coupling Reduction Between Implanted Microstrip Antennas on a Cylindrical Bio-Metallic Ground Plane

The mutual coupling between two antennas within a human body model is studied. Our multilayer cylindrical body model includes highly lossy body tissues under which a biocompatible metal implant is inserted. This cylindrical bio-metal implant serves as the common ground plane for the conformal antennas. The mutual coupling between two such conformal microstrip antennas is studied and quantified for different spacing between them. Three methods are proposed to reduce mutual coupling between the two antennas. Each of them are investigated in details and their effectiveness is compared

Switchable frequency selective surface for reconfigurable electromagnetic architecture of buildings

A frequency selective surface (FSS) that is electronically switchable between reflective and transparent states is tested. It can be used to provide a spatial filter solution to reconfigure the electromagnetic architecture of buildings. The FSS measurements show that the frequency response of the filter does not change significantly when the wave polarization changes or the angle of incidence changes up to +/- 45 degrees from normal. The FSS is based on square loop aperture geometry, with each unit cell having four PIN diodes across the aperture at 90 degree intervals. Experiments demonstrated that almost 10 dB additional transmission loss can be introduced on average at the resonance frequency, for both polarizations, by switching PIN diodes to ON from OFF state

Flexible and transparent circularly polarized patch antenna for reliable unobtrusive wearable wireless communications

This paper presents a circularly polarized flexible and transparent circular patch antenna suitable for body-worn wireless-communications. Circular polarization is highly beneficial in wearable wireless communications, where antennas, as a key component of the RF front-end, operate in dynamic environments, such as the human body. The demonstrated antenna is realized with highly flexible, robust and transparent conductive-fabric-polymer composite. The performance of the explored flexible-transparent antenna is also compared with its non-transparent counterpart manufactured with non-transparent conductive fabric. This comparison further demonstrates the suitability of the proposed materials for the target unobtrusive wearable applications. Detailed numerical and experimental investigations are explored in this paper to verify the proposed design. Moreover, the compatibility of the antenna in wearable applications is evaluated by testing the performance on a forearm phantom and calculating the specific absorption rate (SAR)

High-gain wideband circularly polarized stacked microstrip antennas with single microstrip feeds and short horns

A single feed system is developed to improve the axial ratio bandwidth of circularly polarized rectangular stacked microstrip antennas (CPSMAs) to about 18% by optimizing the feed location and a few other parameters. A main radiator and a parasitic patch of identical size are considered and the separation between them and location of the feed has been optimized to achieve a good AR bandwidth and minimum AR value. For improving the gain of antenna, surface mounted short horn (SMSH) has been used on the CPSMA. The structure has the directive gain of more than the 10dBic over the impedance bandwidth and a 3dB AR bandwidth of 18.8%. The 10dB return-loss bandwidth is 29.6%. The proposed feed system is very useful for rapid design of circularly polarized stacked microstrip antennas with high gain and large AR bandwidth and also very useful to design high gain and wide band microstrip antennas.4 page(s

A Low-profile compact microwave antenna with high gain and wide bandwidth

We demonstrate a low-profile, compact antenna consisting of a cross dielectric resonator on a microstrip patch and a quasi-planar surface mounted short horn (SMSH). The measurements show a 10 dB return loss bandwidth from 6.07 GHz to 7.52 GHz (21.3%) and a gain better than 9.0 dBi over this bandwidth. The total height of the antenna is only 8.61 mm and the aperture size is 48.1 mm 43.1 mm. The cross-polarization level of the antenna at boresight is better than 28 dB in both E-and H-planes over the impedance bandwidth.4 page(s