Comparing beam squinting and reflection cancelling slot methods for return loss improvement in RLSA antennas

In the standard design of the linearly polarised radial line slot array (LPRLSA) antenna, the radiation efficiency is reduced due to accumulative reflections from radiating slots. This paper explores two methods to reduce these reflections. The first method uses additional non-radiative slots which compensate for reflections from the radiating slots. The other modifies the pattern of the radiating slots so that the reflections are minimised but at the same time the antenna´s beam direction becomes squinted. For testing, three prototype surface slot patterns are produced, one standard LPRLSA antenna, one with reflection cancelling slots and one with a squint angle of 20/spl deg/. Measurements on these prototypes indicate that the modified antennas achieve significant improvement in return loss over the standard LPRLSA antenna.