A phased array antenna system for a space-borne platform, said system comprising: a front-end circuit including a plurality of antenna channels where each antenna channel includes a front antenna element and a rear antenna element, said front antenna element being operable to receive signals from the environment or transmit signals into the environment, each antenna channel further including a beam scan phase shifter and a true time delay, TTD, phase shifter through which the receive signals or the transmit signals propagate; a variable attenuator positioned between the beam scan phase shifter and the TTD phase shifter that provides signal attenuation, and an amplifier positioned between the beam scan phase shifter and the front antenna element that is a low noise amplifier for the receive signals from the environment or a high power amplifier for transmitting signals into the environment; and a back-end circuit spaced apart from the front-end circuit and including a single feed horn receiving the receive signals from the rear antenna elements or transmitting the transmit signals to all of the rear antenna elements, said back-end circuit further including an ortho-mode transducer that separates the transmit signals or the receive signals into orthogonally polarized signals, and a first coupler and a second coupler, wherein the ortho-mode transducer includes a first output coupled to a first input of the first coupler and a second output coupled to a second input of the first coupler, and wherein a first output of the first coupler is coupled to a first input of the second coupler and a second output of the first coupler is coupled to a second input of the second coupler, said back-end circuit further including a first polarization phase shifter provided between the second output of the ortho-mode transducer and the second input of the first coupler and a second polarization phase shifter provided between the second output of the first coupler and the second input of the second coupler. a front-end circuit including a plurality of antenna channels where each antenna channel includes a front antenna element and a rear antenna element, said front antenna element being operable to receive signals from the environment or transmit signals into the environment, each antenna channel further including a beam scan phase shifter and a true time delay, TTD, phase shifter through which the receive signals or the transmit signals propagate; a variable attenuator positioned between the beam scan phase shifter and the TTD phase shifter that provides signal attenuation, and an amplifier positioned between the beam scan phase shifter and the front antenna element that is a low noise amplifier for the receive signals from the environment or a high power amplifier for transmitting signals into the environment; and a back-end circuit spaced apart from the front-end circuit and including a single feed horn receiving the receive signals from the rear antenna elements or transmitting the transmit signals to all of the rear antenna elements, said back-end circuit further including an ortho-mode transducer that separates the transmit signals or the receive signals into orthogonally polarized signals, and a first coupler and a second coupler, wherein the ortho-mode transducer includes a first output coupled to a first input of the first coupler and a second output coupled to a second input of the first coupler, and wherein a first output of the first coupler is coupled to a first input of the second coupler and a second output of the first coupler is coupled to a second input of the second coupler, said back-end circuit further including a first polarization phase shifter provided between the second output of the ortho-mode transducer and the second input of the first coupler and a second polarization phase shifter provided between the second output of the first coupler and the second input of the second coupler.