Hybrid Arrays: How Many RF Chains Are Required to Prevent Beam Squint?

TL;DR

This paper investigates the minimum number of RF chains needed in hybrid arrays to effectively prevent beam squint, demonstrating that a threshold exists below the total element count where performance matches fully digital arrays.

Contribution

It establishes that hybrid arrays can achieve near-digital array performance with significantly fewer RF chains than elements, providing a practical design guideline.

Findings

Hybrid arrays can match digital array performance with fewer RF chains.

A threshold number of RF chains exists for effective beam squint mitigation.

Performance robustness extends to beamspace architectures.

Abstract

With increasing frequencies, bandwidths, and array apertures, the phenomenon of beam squint arises as a serious impairment to beamforming. Fully digital arrays with true time delay per antenna element are a potential solution, but they require downconversion at each element. This paper shows that hybrid arrays can perform essentially as well as digital arrays once the number of radio-frequency chains exceeds a certain threshold that is far below the number of elements. The result is robust, holding also for suboptimum but highly appealing beamspace architectures.