Method and apparatus for exciting a television antenna using orthogonal modes

摘要

An antenna driving circuit for connecting an antenna to two transmitters is disclosed. The antenna driving circuit includes a hybrid combiner that has two isolated inputs. The hybrid is configured so that when a first signal is input to the first input, substantially one half of the energy of the first signal is output at the first output and the first signal is phase shifted by about -90 degrees at the first output. Substantially one half of the energy of the first signal is output at the second output and the first signal is phase shifted by about 0 degrees at the second output. When a second signal is input to the second input, substantially one half of the energy of the second signal is output at the second output and the second signal is phase shifted by about -90 degrees at the second output. Substantially one half of the energy of the second signal is output at the first output and the second signal is phase shifted by about 0 degrees at the first output. The input of a first power splitter is connected to the first output of the hybrid combiner and the output of the first power splitter is suitable for driving a first pair of dipole antenna arrays. The first pair of dipole antenna arrays are oriented in substantially opposite spatial directions. The input of a second power splitter is connected to the second output of the hybrid combiner and the output of the second power splitter is suitable for driving a second pair of dipole antenna arrays. The second pair of dipole antenna arrays are oriented in substantially opposite spatial directions that are oriented about 90 degrees away from both of the spatial directions of the first pair of dipole antenna arrays.