RHCP pattern-reconfigurable spiral antenna biased with two DC signals

A right-hand circularly polarized beam steering spiral antenna is presented in this article. It is designed using the standard p-i-n technology, enhanced with arm switches and biasing lines. The ensuing design is easily manufactured and is functionally competitive with the more complex ones, based on RF-MEMS. Three beams, tilted 40° with respect to the spiral central axis, are generated at 3.3 GHz, suitable for WiMax systems at this frequency. These beams are directed at approximately 90°, 180°, and 270° in the azimuth space. Beam directions depend on various configurations of the seven p-i-n diodes added to the spiral structure. The states of the diodes are subjected to the two DC bias voltages connected to the spiral arm. The radiation performance over the 200-MHz bandwidth (3.2–3.4 GHz) is relatively stable. Measurements in this band show the reflection coefficient below −10 dB and the axial ratio below or close to 3 dB at the peak beam directions. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1636–1640, 2014