What is the Hybrid Beamforming Gain?

Hybrid beamforming is a technique to partition beamforming between the digital and RF domains to reduce the cost associated with the
a number of RF signal chains.

Source: Matlab

Hybrid beamforming designs are developed by combining multiple array elements into subarray modules. A T/R module is dedicated to a subarray within the larger array, and therefore fewer T/R modules are required in the system.

The number of elements and the positioning within each subarray can be selected to ensure that system-level performance is met across a range of steering angles.