Cole-Cole relaxation models have been widely used by researchers to extrapolate the measured permittivity of biological tissues to higher frequencies. There is much variability of the measured permittivity from one sample to another for the same type of tissue requiring different Cole-Cole fitting parameters. However, no studies have been conducted on the dependence of the Cole-Cole fitting parameters on tissue constituents such as their geometry, concentration and distribution. In this communication, a single-pole Cole-Cole model is used to fit the frequency dependence of the dielectric permittivity of fatty tissues. Different geometries of water distribution in fat are studied. Multiple scattering full wave simulation is shown to be a useful approach to catalog and analyze different types of geometries. This study can serve as a useful tool to extract more detailed information about a biological tissue from its dielectric permittivity and explain the variation of the measured data.

It is shown that highly focused pulses can be shaped by exciting a finite aperture with a spread-out pulse train of X waves. The basis of the proposed scheme is that the peaks of X waves, characterized by different apex angles, travel at different velocities. This property allows one to vary the temporal starting points of the initial excitations of a sequence of X waves so that all their peaks meet at a chosen focusing point. It is demonstrated that this simple criterion can be effective in producing a highly focused, composite X-wave pulse that exhibits a slower decay behavior than the individual X-wave components used in synthesizing it.

In this study, we introduce a unique geometrical design of a rectangular patch antenna for sub-6 GHz 5G applications. The proposed antenna is designed at 5.2 GHz, and design criteria and performance characteristics have been investigated through numerical simulations and verified using measured data. A composite structure is suggested to overcome the restrictive parameters of conventional antennas. Two different materials, Rogers RT5880, and RT5870, are utilized, achieving a maximum gain of 6.210 dB, and a 90.2% radiation efficiency was attained. Four layers of superstrates are placed above the antenna to enhance the antenna's radiation performance further. The fabricated antenna is evaluated by measuring its radiation characteristics and return loss. The final antenna prototype offers a maximum bandwidth of about 896 MHz at a −10 dB reflection coefficient with a maximum gain of 9 dB. The proposed model achieved ultimate efficiency as high as 89% by employing four superstrates. The results showed good impedance matching (S11, VSWR), high efficiency, and appropriate radiation patterns. The outcomes from simulation and measurement are well aligned, making this antenna suitable for high-performance 5G applications.

A novel design of printed monopole antenna loaded with wire medium is developed for radar applications. The advocated design aims to simultaneously enhance the gain and bandwidth of the proposed geometry. The proposed antenna is composed of a circular patch etched with double C‐shaped slots and the ground is defected to achieve wide bandwidth. Wire medium superstrate and a metal reflector are implemented to provide high gain. The promising tunable wire medium superstrate consists of a periodic array of parallel metallic wires arranged in a rectangular pattern that mimic the behavior of epsilon‐near‐to‐zero (ENZ) metamaterial. This medium is suspended at a distance of a quarter‐wavelength in air above the antenna to provide the optimum gain and reduce the side lobes level. Prototype of the optimized antenna is fabricated using Rogers's substrate to offer −10 dB bandwidth over the entire frequency range (900 MHz to 2.85 GHz). Details of the design process are investigated through full wave electromagnetic simulations performed by CST software. Experimental results of the fabricated prototype are presented and also compared with simulation results where an appreciable agreement between them is demonstrated.