In-Antenna Power Combining for Highly-Integrated Millimeter-Wave Transmitters

In this paper an in-antenna power-combining approach based on a circularly-polarized primary radiator is investigated. The radiation is based on the principle of an integrated lens antenna, where the primary radiator consists of a slot antenna with eight excitation elements. The output power of parallel amplifiers can be directly combined in the primary radiator itself without an additional power combiner network. The bandwidth, efficiency and axial ratio of the proposed primary radiator is investigated through simulations and wherever possible verified by measurements. In this work, the passive antenna, the connected amplifiers and the active antenna are investigated in detail and are finally compared with each other.