FIELD OF THE DISCLOSURE

The disclosure relates generally to solid state power amplifiers and, more particularly, to antenna waveguide transitions for structures for solid state power amplifiers.

BACKGROUND

Traveling wave tube amplifiers (TWTAs) have historically been used to provide broadband microwave power amplification for high power commercial and defense communication applications such as radar, satellite, and electronic warfare. A typical TWTA provides amplification through the interaction of a radio frequency (RF) field and an electron beam within a vacuum tube. While TWTAs provide adequate output power necessary for high power applications, there are several drawbacks, including short lifetime, poor linearity, high cost, large size and weight, and the requirement of a high drive voltage.

In recent years, solid state power amplifier (SSPA) devices have begun to replace TWTAs for broadband microwave power amplification. SSPAs generate lower noise and have improved linearity when compared to TWTAs. Additionally, SSPAs provide superior reliability while achieving high output powers, bandwidths, and efficiencies needed for various applications. An SSPA is able to provide these operating characteristics while at the same time providing a device with a smaller overall size and weight.

In a typical SSPA, an electromagnetic signal is split across multiple amplifiers for amplification. Power combining schemes are utilized to subsequently combine outputs from the multiple amplifiers into an amplified output signal. The art continues to seek improved SSPAs that provide improved combinations of output power, bandwidth, and efficiency and are capable of overcoming challenges associated with conventional broadband power amplification devices.

SUMMARY

Aspects disclosed herein include antenna waveguide transitions for solid state power amplifiers (SSPAs). An SSPA includes a waveguide channel that is configured to propagate an input signal, such as an electromagnetic signal, from an input port to a solid state amplifier for amplification. The waveguide channel is further configured to propagate an amplified signal from the solid state amplifier to an output port. Waveguide transitions to and from the solid state amplifier may be bandwidth matched to the waveguide channel. Additionally, the waveguide transitions may be thermally coupled to the waveguide channel. The waveguide transitions may include antenna structures that have a signal conductor and a ground conductor. In this manner, the SSPA may have improved broadband coupling, as well as improved thermal dissipation for heat generated by the solid state amplifier.

In some aspects, an SSPA includes a solid state amplifier; an input port and an output port; a waveguide channel configured to propagate an input signal from the input port to the solid state amplifier and configured to propagate an amplified signal from the solid state amplifier to the output port; an input antenna structure inside the waveguide channel that is configured to transition the input signal from the waveguide channel to the solid state amplifier; and an output antenna structure inside the waveguide channel that is configured to transition the amplified signal from the solid state amplifier to the waveguide channel. In some embodiments, the input antenna structure further comprises an input signal conductor and an input ground conductor. The input signal conductor and the input ground conductor are on opposing faces of a substrate or they may be separated by air. In some embodiments, the input antenna structure and the output antenna structure are bandwidth matched to the waveguide channel. In some embodiments, at least one of the input antenna structure and the output antenna structure are thermally coupled to one or more walls of the waveguide channel. The solid state amplifier may include a monolithic microwave integrated circuit (MMIC) amplifier, such as a gallium nitride (GaN)-based MMIC.

In some aspects, an SSPA includes a plurality of solid state amplifiers; an input port and an output port; a waveguide channel connected to the input port and the output port, wherein the waveguide channel comprises: a first plurality of waveguide segments that individually connect with separate solid state amplifiers of the plurality of solid state amplifiers; and a second plurality of waveguide segments that individually connect with separate solid state amplifiers of the plurality of solid state amplifiers and combine the waveguide channel; a plurality of input antenna structures inside the first plurality of waveguide segments that are configured to transition portions of a signal propagating through the first plurality of waveguide segments to the plurality of solid state amplifiers; and a plurality of output antenna structures inside the second plurality of waveguide segments that are configured to transition portions of an amplified signal from the plurality of solid state amplifiers to the waveguide channel. In some embodiments, the plurality of solid state amplifiers comprises at least four solid state amplifiers. In some embodiments, each input antenna structure of the plurality of input antenna structures comprises an input signal conductor and an input ground conductor. In some embodiments, the input signal conductor and the input ground conductor are on opposing faces of a substrate. In other embodiments, the input signal conductor and the input ground conductor are separated by air. In some embodiments, each output antenna structure of the plurality of output antenna structures comprises an output signal conductor and an output ground conductor. The output signal conductor and the output ground conductor may be on opposing faces of a substrate or they may be separated by air. In some embodiments, at least one input antenna structure of the plurality of input antenna structures and at least one output antenna structure of the plurality of output antenna structures are thermally coupled to a wall of the waveguide channel. In some embodiments, the SSPA includes a housing that includes a plurality of housing segments that form the waveguide channel. In further embodiments, the plurality of housing segments comprises a plurality of hollow channels that form the waveguide channel.

Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.

