An apparatus (100; 1200), comprising: a first port (110; 1210) configured to convey a first signal at a first frequency; a second port configured to convey a second signal at a second frequency, said second frequency being higher than said first frequency; a third port configured to convey said first signal and said second signal with a feed for a multiband antenna, said third port having an inner waveguide and a coaxial waveguide , an inner surface of the coaxial waveguide defining an outer surface of the inner waveguide; a first network coupling said first port with said coaxial waveguide and configured to propagate said first signal between said first port and said coaxial waveguide; and a second network (910; 920) coupling said second port with said inner waveguide and configured to propagate said second signal between said second port and said inner waveguide, wherein said first network comprises a coaxial turnstile junction having waveguides extending radially therefrom configured to convert said first signal between a first mode in said first network and a coaxial mode in said coaxial waveguide and wherein the coaxial turnstile junction comprises tuning surface variations between the waveguides, said first network comprises a first signal splitter configured to convert between said first signal and an in-phase first signal and an opposing phase first signal, and said first signal splitter comprises a T-junction splitter having a splitter port configured to convey said first signal, an in-phase port configured to convey said in-phase first signal and an opposing phase port configured to convey said opposing phase first signal. a first port (110; 1210) configured to convey a first signal at a first frequency; a second port configured to convey a second signal at a second frequency, said second frequency being higher than said first frequency; a third port configured to convey said first signal and said second signal with a feed for a multiband antenna, said third port having an inner waveguide and a coaxial waveguide , an inner surface of the coaxial waveguide defining an outer surface of the inner waveguide; a first network coupling said first port with said coaxial waveguide and configured to propagate said first signal between said first port and said coaxial waveguide; and a second network (910; 920) coupling said second port with said inner waveguide and configured to propagate said second signal between said second port and said inner waveguide, wherein said first network comprises a coaxial turnstile junction having waveguides extending radially therefrom configured to convert said first signal between a first mode in said first network and a coaxial mode in said coaxial waveguide and wherein the coaxial turnstile junction comprises tuning surface variations between the waveguides, said first network comprises a first signal splitter configured to convert between said first signal and an in-phase first signal and an opposing phase first signal, and said first signal splitter comprises a T-junction splitter having a splitter port configured to convey said first signal, an in-phase port configured to convey said in-phase first signal and an opposing phase port configured to convey said opposing phase first signal. <EOS>