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The Theory of Characteristic Modes (TCM) is proposed as a systematic approach to antenna design to achieve the goal of finding the antenna structure with optimum broadband behavior. This theory provides a physical insight to the radiating nature of microstrip patch antennas and reduces the design optimization time. In this work, the resonant behavior of the highly radiating structure of the single U-slot rectangular patch on a single-layer εr = 4.4 substrate is analyzed using TCM. Modal analysis of this single-layer structure with different single feed excitations concludes that VSWR ≤ 2 impedance bandwidth in the order of 96% can be achieved with a single T-probe feed. Experimental results, included here, show VSWR ≤ 2 impedance bandwidth in the order of 71%. [ABSTRACT FROM AUTHOR]

Ultra-wideband (UWB) phased arrays are increasingly used in radar and medical applications. Mutual coupling reduction between the phased array elements is critical in achieving good scan bandwidth. This study investigates the mutual coupling of a UWB U-slot microstrip patch 2-element array to find the patch orientation and U-slot topology with the least mutual coupling. Electromagnetic (EM) simulation results indicate that, for εr = 2.2 substrate, diamond patch orientation with opposite U-slot topology has the least coupling between the array elements. Results also indicate that the current density distribution on the microstrip patch has an effect on mutual coupling between the array elements. Results show good agreement between MoM and FEM EM solvers. [ABSTRACT FROM AUTHOR]

The need for low-profile and ultra-wideband (UWB) antennas is rising in wireless communication and medical applications. The method of dimensional invariance, which is a class of U-slot patch design methods, is utilized to realize an initial, low-profile, wideband design. Building on this initial wideband design, this study establishes ideal L-probe feed dimensions through extensive parametric study on εr = 2.2 and 4.5 substrates to propose empirical guidelines for the design of L-probe feeds which yield first-pass optimum impedance bandwidth. The established ideal L-probe dimensions, after further extrapolation, are used successfully on other substrates, εr = 3.27, 6.0 and 9.2, for the design of first-pass L-probe feeds which yield impedance bandwidth over 55%, 60%, and 53%, respectively. The results of three commercially available EM simulation solvers show good agreement [ABSTRACT FROM AUTHOR]

This paper presents electromagnetic (EM) absorption loss over breast mass as a new approach in the detection of breast cancer tumors. A linear curve of absorption loss over breast mass is used to establish acceptable normal absorption loss values. Since tumor-infected breast tissues should have higher absorption loss than normal breast tissues, the measured absorption loss of a tumor-infected breast will be higher than the established normal absorption loss value, and the breast will be diagnosed as infected. EM simulations of normal and infected breast tissues are run at 915, 2450, and 4000 MHz. Results show that 915 MHz presents the best linear curve fit and resolution. Also, the absorption loss for an infected breast, at 915 MHz, is higher than the absorption loss for a normal breast and is least affected by tumor location.