A Novel (1.05 to 1.25) GHz Filtering Antenna Feeding Network With Reconfigurable Frequency and Polarization

In this article, a novel 1.05-1.25 GHz filtering antenna feeding network with reconfigurable frequency and polarization is proposed. It simply consists of a reconfigurable in-/out-of-phase filtering power divider (RFPD) and a 90° hybrid coupler. By controlling the varactors in the RFPD without any switch component, the proposed 3-port feeding network offers continuous reconfigurable filtering responses with four switchable output patterns including: equal power dividing with phase difference of negative or positive 90°, single-ended output at either output port. With this proposed feeding network connecting to a regular dual-polarized antenna, the resulted antenna system can easily realize reconfigurable polarization of vertical polarization (V-LP), horizontal polarization(H-LP), left-handed circularly polarization (LHCP) and right-handed circularly polarization (RHCP), in addition to its reconfigurable filtering responses. A prototype using microstrip technology is designed, fabricated and measured to demonstrate the proposed technique. Good agreement between simulated and measured results is obtained. The measured results show that the feeding network covers a frequency range of 1.05-1.25 GHz, and the error of phase difference and amplitude imbalance are less than 5° and 0.5 dB, respectively. The resulted antenna beams can be freely switched in four polarization states with good performance.