The high power RF circuit board is designed with 0 pins.Mixer RF Type from the Evaluation board.Try searching with HMC521 if you're looking for variants.RF Board is included in the PCB mount.
109998-HMC521LC4 Features
0 pins Mixer Type
109998-HMC521LC4 Applications
There are a lot of Analog Devices Inc. 109998-HMC521LC4 RF Boards applications.