Unilateral/Nonreciprocal Filter Design: Recent Advances and Emerging Strategies

Next-generation wireless systems demand highly-modular and highly-functional RF transceivers with ultra small size, weight, power and cost (SWaP-C). Unilateral/non-reciprocal filters, which combine frequency selectivity with directional transmission, are vital for the development of smaller, multi-functional and flexible RF systems. The paper reviews recent advances and emerging design strategies for unilateral filters, with a particular emphasis on reconfigurability, and multi-functional designs are discussed. This paper also highlights ongoing challenges and future research directions for this rapidly developing field.