1-to- $N$ Ring Power Combiners With Common Delta Ports

In this paper, we present a new 1-to-N way ring combiner that is an adaptation of the ring-hybrid (rat-race) structure. We present the general design guidelines for N-way planar ring combiners based on theoretical analysis of the structures. The proposed 1-to-N way ring structure offers a compact, planar layout that includes a single common delta port. This is beneficial to applications where power monitoring, calibration, or energy recycling can be leveraged. It offers similar loss to other N-way structures. To demonstrate the combiners operation, we present completely passive structures and structures with embedded power amplifiers for 4- and 6-way variants. The designs are optimized for operation in the 5-6 GHz unlicensed bands. The passive 4- and 6-way combiners achieve IL of 1.3 and 1 dB, respectively, with associated port isolations of <;-30 dB. The combiners with embedded amplifiers show similar performance and are validated using modulated signals and demonstrate good measured linearity when combining up to 6 amplifiers for output powers >1 W.