Polarization converting antenna

A new type of polarization converting antenna has been introduced. This antenna receives vertically polarized signals and re-radiates it with horizontal polarization, or vice-versa. This type of polarization converting antenna is useful for responder applications. The responder is a passive version of a transponder. The background noise or spurious echo is effectively removed by this type of antenna. The mode converting antenna can be utilized in the "in-line" mode or in the "reflection" mode. In the in-line mode, the antenna is placed between the transmitter and the receiver. In the reflection mode operation, the antenna is facing both the transmitter and the receiver which are on the same side. A direct coupled vertical/horizontal half-wave dipole antenna of 32mm long in-each direction was constructed and tested in the reflection mOde. The vertical element receives the vertically polarized waves and excites the horizontal element which is directly coupled to the vertical element at the current maximum point. The test frequency was 9.12 -9.745 GHz . The vertical to horizontal conversion loss was 15db but the signal to noise ration improvement, was more than 30 db.