Date of Award

2020

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical Engineering

First Advisor

Jeff Frolik

Second Advisor

Adrian Del Maestro

Abstract

The increased use of internet of things (IoT) devices will result in them being deployed

in a wide variety of environments and therefore warrant antenna systems that can be

adapted to improve link performance. Flexible communication technologies allow for

increased throughput, reliability, and improved efficiency in wireless channels. This

can be accomplished by implementing phased array antennas, among others. Phased

arrays create a beam that can be steered electronically, but are expensive to implement

given the many phase precise hardware components that need to be adjustable. A

software defined radio approach to beamforming can reduce this complexity for each

array adaptation, if made in software.

This thesis leverages software defined radio (SDR) for the purpose of phase measurements

and beamforming. A phase measurement system was created in GNU

Radio to determine phase differences between SDRs. This algorithm was tested on

a direction-finding system measuring the angle of arrival of a moving transmitter.

In addition, transmit beamforming was implemented via SDR on a tripolar array

and a four-element patch antenna array. Through simulation, the tripolar array has

an 3 dB improvement in gain over a single monopole antenna in azimuth. The

measured antenna patterns did not match the simulation, but the reconfigurability

of the SDR platform provided the ability to correct the nonidealities in the physical

antenna. The azimuth test results show that beamsteering can be accomplished with

a median power increase of 3 dB over the omnidirectional beamsteering case. The

patch antenna array was tested by simulating a Butler matrix, a beamforming network

typically implemented in hardware. The array pattern had a 3 dB beamwidth

of 22° in simulation and 20° through testing, with a maximum steering error of

3° across the four Butler cases. The presented validation of the phase measurement

and beamforming systems is promising for future work in the realm of beamforming

via software defined radio.

Language

en

Number of Pages

93 p.

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