Antenna arrays are widely used in wireless communication, radar, remote sensing, and other fields. Compared to traditional linear antenna arrays, novel nonlinear antenna arrays have fascinating advantages in terms of structural simplicity, lower cost, wider bandwidth, faster scanning speed, and lower side-lobe levels. This dissertation explores a novel design of a phased array antenna with an augmented scanning range, aiming to establish a clear connection between mathematical principles and practical circuitry. To achieve this goal, the Van der Pol (VDP) model is applied to a single-transistor oscillator to obtain the isolated limit cycle. The coupled oscillators are then integrated into a 1 times 7 coupled phased array, using the Keysight PathWave Advanced Design System (ADS) for tuning and optimization. The VDP model is used for analytic study of bifurcation, quasi-sinusoidal oscillation, quasi-periodic chaos, and oscillator death, while ADS schematics guide engineering implementation and physical fabrication. The coupled oscillators drive cavity-backed antennas, forming a one-dimensional scanning antenna array of 1 times 7. The approaches for increasing the scanning range performance are discussed.

Two commercial blade antennas for aircraft applications are investigated. The computed results are compared with measurements performed in the ASU ElectroMagnetic Anechoic Chamber (EMAC). The antennas are modeled as mounted on a 13-inch diameter circular ground plane, which corresponds to that of the measurements. Two electromagnetic modeling codes are used in this project to model the antennas and predict their radiation and impedance characteristics: FEKO and WIPL-D Pro. A useful tool of WIPL-D Pro, referred to as WIPL-D Pro CAD, has proven to be convenient for modeling complex geometries. The classical wire monopole was also modeled using high-frequency methods, GO and GTD/UTD, mounted on both a rectangular and a circular ground plane. A good agreement between the patterns of this model and FEKO has been obtained. The final versions of the solvers used in this work are FEKO (Suit 6.2), WIPL-D Pro v11 and WIPL-D Pro CAD 2013. Features of the simulation solvers are presented and compared. Simulation results of FEKO and WIPL-D Pro have good agreements with the measurements for radiation and impedance characteristics. WIPL-D Pro has a much higher computational efficiency than FEKO.