Investigation of Aperture Coupled Microstrip Antenna to Obtain a High Efficient Active Integrated Antenna by Using Class F and Inverse Class F Power Amplifiers

Liu, Lei (2013) Investigation of Aperture Coupled Microstrip Antenna to Obtain a High Efficient Active Integrated Antenna by Using Class F and Inverse Class F Power Amplifiers. Doctoral thesis, University of Northumbria.

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Abstract

In wireless communications and radar systems, there are requirements for high efficiency, small size, low cost, and wide bandwidth of transmitter front –end usage for commercial and also military applications. Active integrated antenna (AIA) could satisfy almost all the requirements. The overall objective of the proposed research is to model, optimise, and design a compact and high efficient AIA using an aperture coupled microstrip antenna (ACMA) by integrating with a power amplifier (PA). Research on ACMA has been focused on the transmissions line (TL) model (TLM) and full wave electromagnetic (EM) model analysis. The full wave investigation is rigorous and elegant but because the dimension of the physical model and the value of the circuit elements are interdependent, the design of the antenna is still difficult. TLM analysis has lower accuracy but easier to analysis and optimise than full wave EM model analysis. To increase the accuracy, the challenge is the coupling ratios between feed/slot, and slot/patch where no unique solution at the moment exists. In this thesis, a novel and simplified method has been produced to investigate these ratios using Scattering (S) parameters. A dual frequency ACMA has been designed to verify these results. Research on the class F and inverse class F PAs is carried out by a novel and simplified load/pull method. A new design method of harmonic load matching network has been presented using lump elements and TLs. Both linear and nonlinear modelling has been investigated. High power added efficiency (PAE) and high gain which are up to 60% and 12dB have been obtained. Finally AIAs have been produced based on previous investigation on class F, inverse class F PAs and a broadband circular polarized ACMA design with 350 MHz bandwidth and 8.5 dB gain at 2 GHz.

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