High-Efficiency Periodic Sparse Patch Array Based on Mutual Coupling

The loss and cost introduced by the feeding network and the associated components, e.g., T/R modules or phase shifters and so on, of a large array antenna are the main issue limiting its efficiency and applications. A novel idea in order to build a sparse periodic patch array is presented while keeping similar aperture efficiency by taking advantage of mutual coupling between array elements, and then the total cost of the array can be obviously decreased. Operating principles are carefully addressed based on electric field distributions and impedance matrix. Simulations and measurements show that when the active element spacing is as large as 1.67λ₀ (λ₀ is the free-space wavelength at the operating frequency), approximately equal directivity can be achieved, compared to an ideal conventional array with a half-element spacing (0.835λ₀) and an identical total size.