Title

Wideband Phased Array Design and Characterization

Date of Award

May 2014

Degree Type

Dissertation

Embargo Date

8-7-2016

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical Engineering and Computer Science

Advisor(s)

Tapan k. Sarkar

Second Advisor

Samuel P. Clemence

Keywords

antenna, flared notch, multioctave, phased array, scattering, wideband

Subject Categories

Engineering

Abstract

This dissertation presents the empirical design and electrical characterization of a unique antenna element suitable for use in polarization diverse wide frequency bandwidth phased arrays. The development of this wideband phased array antenna for use in airborne multi-function radar and electronic warfare systems is discussed in the context of the advancement of monolithic microwave integrated circuit technology. The general behavior of several classes of frequency independent antennas and their applicability for wideband phased arrays are examined. The emergence of the stripline-fed flared notch antenna as the best-suited element type for finite wideband phased arrays is discussed in terms of antenna performance, array architecture, and compatibility with Bragg lobe restrictions.

Both conformal and non-conformal versions of wide frequency bandwidth antenna designs are investigated for their electrical performance behavior over a multi-octave frequency bandwidth. A unique non-conformal antenna element is achieved by combining, with a power divider, two like-polarized flared notch antennas into a two-element subarray. This subarray element is essential in creating double density arrays that meet octave bandwidth antenna grating lobe and multi-octave bandwidth Bragg lobe lattice spacing restrictions. Several single and double density arrays with both linear and dual polarizations are designed, built, and measured to characterize in situ array-element performance behavior. This in situ array-element antenna performance includes scan impedance, scan element pattern, and gain.

The dissertation also discusses the parallel advent of electromagnetic formulations and computer simulation codes capable of modeling and predicting the radiation and scattering of complex integrated phased array and radome problems. Simulations are presented that provide insight into the near-field behavior of antenna radome interactions. The resonances visible in the near-field are shown to create significant distortions in the far-field antenna and scattering patterns. An application of electromagnetic computer simulation in illustrating a complex antenna and radome integration problem is presented. The potential benefit of using electromagnetic simulation software to optimize the gain and scattering of an integrated aircraft leading edge phased array and radome of complex media is detailed.

The application of this wideband stripline flared notch design in two demonstration phased arrays are presented in terms of both architectural design and electrical performance. Both a single density linear polarized array and double density dual polarized phased array are discussed. The double density array is shown to be advantageous in reducing the number of T/R modules in wideband planar phased arrays. An improvement in the E-plane scan impedance is shown in double density arrays with closely spaced antenna array-elements. The use of radar absorbing material in the double density array also enhances the H-plane beamwidth, cross-polarization level, and gain performance.

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