A two-layer higher order mode circularly polarised (CP) rectangular dielectric resonator antenna (RDRA) is proposed at a frequency range of 10 to 13 GHz using a single-feed. The configuration incorporates the DRA and a dielectric coat with respective dielectric constants of 10 and 3.5. Utilising the outer layer offers a number of advantages such as wider impedance and CP bandwidths of μ21%, and 9.5%, respectively, as well as a high gain of ~11dBic. Close agreement has been achieved between experimental and simulated results.

A compact multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) that is suitable for internet of things (IoT) sensor networks is proposed with reduced coupling between elements. Two rectangular-shaped DRAs have been placed on the opposite sides of a Rogers substrate and each is fed using a coplanar waveguide (CPW) feed with slots etched in a dedicated metal ground plane that is located under the DRA. Moreover, locating the elements at the opposite sides of the substrate has improved the isolation by 27 dB without the need to incorporate additional complex structures, which has reduced the overall antenna size. Furthermore, a dual band operation is achieved since each antenna resonates at two frequencies: 28 GHz and 38 GHz with respective impedance matching bandwidths of 18% and 13%. As a result, the corresponding data rates are also increased independently. In addition to the advantages of improved isolation, compact size and dual band operation, the proposed configuration offers a diversity gain (DG), envelope correlation coefficient (ECC) and channel capacity loss (CCL) of 9.98 dB, 0.007, 0.06 bits/s/Hz over the desired bands, respectively. A prototype has been built with good agreement between simulated and measured results.

In the paper, an extremely compact multiple-input-multiple-output (MIMO) antenna is proposed for portable wireless ultrawideband (UWB) applications. The proposed prototype consists of four monopole antenna elements, which are placed perpendicularly to achieve polarization diversity. In addition, the mutual coupling between antenna elements is suppressed by designing the gap between the radiation element and the ground plane. Moreover, a matching stub has been connected to the feedline to ensure impedance matching in high frequency. Both simulated and measured results indicate that the proposed antenna has a bandwidth of 3–20 GHz, with a high isolation better than 17 dB. In addition, the designed MIMO antenna offers excellent radiation characteristics and stable gain over the whole working band. The envelope correlation coefficient (ECC) is less than 0.1, which shows that the antenna can meet the polarization diversity characteristics well.

A flexible and totally wearable textile antenna is proposed by embroidering the conductive threads into garments. A purely polyester substrate has been utilized, which provides a tag that can be easily integrated with the clothes. The proposed tag antenna is small with dimensions of 72 × 20 × 2.75 mm³ and offers an enhanced performance in terms of gain and stability when worn on different body locations. Experimental results demonstrate an improved impedance matching owing to the elasticity of the E-shaped inductive feeder. Close agreement has been achieved between the simulated and measured results.

The realization of all-semiconductor epitaxially regrown photonic crystal (PC) surface-emitting lasers is reported. PC coupling strengths, band structure, optimization of epitaxial regrowth, and operating characteristics are discussed. Room temperature operation allows agreement between theoretical and experimental band structure to be confirmed.

Asymptotic expressions are derived for the dyadic Green's functions of antennas radiating in the presence of a multilayered cylinder, where analytic representation of the asymptotic expansion coefficients eliminates the computational cost of numerical evaluation. As a result, the asymptotic extraction technique has been applied only once for a large summation order. In addition, the Hankel function singularity encountered for source and evaluation points at the same radius has been eliminated using analytical integration.