In this article, a novel double-face logarithmic spiral metamaterial (LSMTM) superstrate-inspired multiple-input multiple-output (MIMO) for fully enhanced circularly polarized (CP) antenna system is examined for 5G wireless communications. This novel double-face LSMTM superstrate acts as a planar concave-concave lens. Initially, the antenna is designed with a circular spiral patch to generate CP radiation in the frequency band of interest. Then, at a height of 6.5 mm (0.606 λo) above the MIMO antenna, which has a 0.8 mm (0.075 λo) edge-to-edge separation, the LSMTM superstrate is employed for isolation, gain, and bandwidth improvement. The proposed superstrate enhances the isolation, gain, and bandwidth of the antenna by about 32 dB, 3.47 dB, and 900 MHz, respectively. In contrast to the conventional technique of verifying operation with a simulated surface current distribution, characteristic mode analysis (CMA) is used to provide a better explanation of the proposed antenna's different modes and the creation of circular polarization. Additionally, the CMA supports the development of an effective technique that can predict whether or not the isolation can be further improved. The simulated results align with the measured results and are well adapted for 5G wireless communication devices.

To design a low radar cross section (RCS) antenna, the major concern is not only to reduce scattering, but also to maintain its radiation parameters, viz. gain, voltage standing wave ratio (VSWR), etc. This paper presents a simple configuration of low RCS microstrip patch array with a periodic structure-based superstrate. The ground of the array is designed as reduced ground plane with high impedance surface elements, viz. rectangular patch and Jerusalem cross. The configuration of superstrate consists of multilayered, viz., two-layered and three-layered structures having partially absorbing and reflecting surfaces. In both the proposed configurations, the array gain of 12.5 dB is maintained with reduced structural RCS over the entire in-band frequency range. The reflection coefficient (~ −20 dB) and VSWR (~ 1.1) of the array are maintained. It is shown that the proposed superstrate-based patch array design has significantly reduced in-band RCS (−18 dBsm) at its resonant frequency.

A superstrate loaded cylindrical dielectric resonator antenna is developed and demonstrated for dual-band circular polarization. The proposed antenna employs a microstrip-fed rotated cross-shaped slot coupling technique for exciting the dielectric resonator (DR). The design is developed in a straight forward way. Firstly, the DR is coupled with a conventional plus-shaped slot and operates in linear polarization mode at 7.4 and 11.2 GHz. Secondly, the slot is rotated by 10° to enable out-of-phase excitation and ensure circular polarization at the above-mentioned frequencies. In the third step, a square dielectric superstrate is placed above the DR which creates multiple reflection and enhance the gain up to ~8 dBi in both the frequencies without affecting other performances. The development stages are discussed in detail. The proposed design is demonstrated through prototype fabrication and characterization. This antenna can be used for X-band satellite communications.

In this paper, a simple conical-shaped dielectric resonator antenna operating in HEM11δ mode is presented for X-band wireless applications. A rectangular slot with a running microstrip line is used for excitation purpose. By placing a FR-4 based superstrate at 7 mm height from the ground FR-4 substrate and incorporating a set of modified ground plane on either side of the feed line, gain is improved by 42.85% and bandwidth by 68.92%, simultaneously. A prototype of designed antenna is fabricated and characterized. The measured results are found to be good in matching with the simulated ones.