Analysis and Design of a Millimeter Wave Cavity Backed Circularly Polarized Radiator Based on Fundamental Theory of Multi Port Oscillators
This paper presents the design and implementation of a millimeter wave fundamental frequency circularly polarized radiator, which employs a multi port cavity as the core of a high <inline formula> <tex math notation="LaTeX"$Q$ /tex math>/inline formula> resonator, a power combiner, and an antenna. A general theory of multi port oscillators and in particular, the widely used circularly symmetric oscillator topologies is presented, which quantitatively investigates and predicts all possible oscillation states, their associated modes of operation, and the oscillation stability. The outcomes of this theory are utilized to design a power optimized eight port rotationally symmetric radiator, excited at the oscillation state with a 45 phase difference between the adjacent ports, which, in turn, enables a high efficiency circularly polarized radiation. Fabricated in 0.13 <inline formula> <tex math notation="LaTeX"\mu \text{m} /tex math>/inline formula> BiCMOS process, this cavity backed circularly polarized radiator operates at the frequency of 114 GHz and achieves 14.2 dBm equivalent isotropic radiated power (EIRP) 5.2% dc to EIRP conversion efficiency, 8.2 dBm radiated power, 1.3% dc to radiation efficiency, and 99.3 dBc/Hz phase noise at 1 MHz offset, without using silicon lens.
IEEE Journal of Solid State Circuits