Online

Fennelly, Evan Michael

Electrical and Biomedical Engineering

2020

M.S.

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.