A man-pack portable, multi-band ultra-high frequency turnstile-type SATCOM radio antenna for transmitting and receiving radio signals between terrestrial locations and an orbiting earth satellite includes a cylindrically shaped antenna superstructure base which has an elongated mast extending forward from a front transverse end wall of the base, and circumferentially spaced apart pairs of radiating elements which extend radially outwards from the mast, each opposed pair comprising in combination an electric dipole antenna which is electrically connected via coaxial cables disposed longitudinally through the mast to zero and ninety degree ports of a hybrid antenna matching network located in the base and having an input port electrically connected to a coaxial antenna base connector located in a rear transverse end wall of the base. A diplexer which includes a cylindrical housing longitudinally alignable with the base contains a low-frequency band-pass filter and a high-frequency band-pass filter having low and high center frequencies, respectively, the filters having a common output node electrically connected to coaxial diplexer output connector located on a front transverse end wall of the diplexer housing and longitudinally engageable with the antenna base connector. The diplexer has on a rear transverse end wall thereof two coaxial transceiver connectors connected to separate nodes of the high and low frequency filters, the transceiver connectors being connectable via coaxial cables to one or more radio transceivers, which are thus enabled to operate simultaneously in different frequency bands, without requiring any external diplexer.