Abstract: A duo-quad wideband wave guide combiner includes a circular waveguide having a center axis with a cross section with four quadrants; and two waveguides, each waveguide being bifurcated at an input to the wave guide combiner by a thin septum to split each of the two waveguide into two bifurcated waveguides, each of the bifurcated waveguides rotating to a respective one of the four quadrants about the center axis of the circular waveguide with converging walls terminating when a composite cross section becomes circular.

Abstract: An improved transverse electromagnetic (TEM) horn antenna comprises a resistive loading material on the exterior surfaces of the antenna plates. The resistive loading material attenuates or inhibits currents on the exterior surfaces of the TEM horn antenna. The exterior electromagnetic fields are of opposite polarity in comparison to the primary and desired interior electromagnetic field, thus inherently cause partial cancellation of the interior wave upon radiation or upon reception. Reducing the exterior fields increases the radiation efficiency of the antenna by reducing the cancellation of the primary interior field (supported by the interior surface currents). This increases the transmit gain and receive sensitivity of the TEM horn antenna, as well as improving the transient (time-domain) response.