Document Type



Doctor of Philosophy (PhD)


Electrical and Computer Engineering

First Advisor's Name

Elias A. Alwan

First Advisor's Committee Title

Co-committee chair

Second Advisor's Name

John L. Volakis

Second Advisor's Committee Title

Co-committee chair

Third Advisor's Name

Arjuna Madanayake

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Pezhman Mardanpour

Fourth Advisor's Committee Title

Committee member


Antenna arrays, antenna subarrays, beamforming, frontend circuitry, front end circuits and systems, RF front ends, self-mixing, self-mixing array, self-mixing subarray, wideband apertures, wide beamwidth

Date of Defense



Research is showing an interest in redefining phased arrays and devising more flexible low-profile receivers. As such, there is a need to compensate for the bulkiness of existing systems which is mainly imposed by the phase shifters placed after each element. That is, we must circumvent hardware limitations by searching for alternatives for phase shifting the signals to introduce more flexibility in signal reception for more downsized radio systems. Therefore, self-mixing arrays are developed and now deployed for the beamforming process. The concept stems from applying mixing instead of shifting to eliminate the delays in reception. Central to its realization is mixing the elements with themselves. As a result, the mixing process yields a cancellation of the delays in reception and allows for coherent signal combining.

Current self-mixing beamformers are flexible to angles of arrival (AoAs), which is not feasible with traditional phased arrays. Such beamformers offer autonomous behaviour in phase delay compensation from any AoA. As such, the system receives the signal from all directions with a much finer angular resolution as compared to traditional beamformers. However, this enhancement in spatial coverage makes the system more vulnerable to interference from other users. In this regard, despite this unprecedented flexibility to AoA, the design encounters a degradation in interference mitigation and is limited only to analog beamforming configurations.

Consequently, we introduce a novel cross-mixing array design capable of avoiding this conundrum. Instead of mixing the elements with themselves, we proceed with a cross-element mixing beamforming (CMB) method wherein the elements engage in mixing one another. By doing so, we not only eliminate all delays in reception, but we can also preserve the AoA information of the received signal. As such, CMB knows the direction of the desired source and hence is capable of blocking the signals from all unwanted directions. More important, the cross-mixing architecture can be associated with hybrid beamforming configurations, which is not realizable with the other existing self-mixing array topologies. Therefore, CMB sets a precedent for self-mixing sub-array architectures and provides avenues for a new class of self-mixing beamforming.




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