PCB Slot Based Transformers to Avoid Common-Mode Resonances in Connected Arrays of Dipoles

The scanning performances of connected arrays are degraded by the excitation of common-mode resonances that are compatible with balanced feeding lines. Here, a strategy to avoid these resonances is outlined. The strategy involves feeding the dipoles via printed circuit board (PCB) based transformers and significantly reducing the feeding periods in the direction of the dipoles. The number of transmit/receive (T/R) modules does not have to be increased as a consequence of the increased sampling of the dipoles. Full wave simulations that validate the procedure are presented.