A novel aperture-isolation circuit for use in phased array systems

A novel electronically controlled matching network has been demonstrated as an aperture-isolation circuit. This approach offers smaller size, lower weight, and potentially lower cost than circulators. The circuit presently demonstrated has loss comparable to a circulator, however, in certain applications (e.g., lower frequency of operation) and with improved devices, it is anticipated that this approach will offer lower insertion loss than circulators. Monolithic microwave IC (MMIC)-compatible GaAs p-i-n diodes have demonstrated a cutoff frequency of 2.4 THz and a breakdown voltage of 95 V. The aperture-isolation MMIC was designed to match radiating element impedances with reflection coefficients of tip to 0.5 of any phase. The designed frequency band was 9.2-10.2 GHz. The vertical p-i-n diode structure, circuit design, and performance are described.<>