Abstract: The disclosure relates to a four-port diplexer device which includes a first port configured to pass signals within a first frequency band and to block signals within a second frequency band; a second port configured to pass signals within the second frequency band and to block signals within the first frequency band; a third port configured to transmit a first signal portion of a combination of the signals received from the first port and the signals received from the second port; and a fourth port configured to transmit a second signal portion of the combination of the signals received from the first port and the signals received from the second port.

Abstract: A horn antenna element includes a septum polarizer configured to transform a linear polarized input signal into a circular polarized output signal at a common port, and a horn radiator. The horn radiator includes an input geometry formed as a quad-ridge waveguide to receive the circular polarized output signal at the common port and an aperture grid to radiate a grid-based circular polarized output signal. The septum polarizer is embedded in the quad-ridge waveguide at the common port.