Wideband Dual Circularly Polarized Helical Antenna Array for Satellite Applications
Chunxu Mao, Mohsen Khalily, Rahim Tafazolli, Ahmed A. Kishk
Abstract
A novel wideband dual-sense circularly polarized (CP) helical array antenna with enhanced isolation is proposed in this letter. The left-handed CP (LHCP) and the right-handed CP (RHCP) radiation in the same band are realized by exciting two concentric helical antennas with different radii and winding directions. The parameters of the two concentric helical antennas are studied to keep them operate in the same frequency range while maintaining good CPs performance. To achieve a high isolation between the two nested helical antenna, the parameters, such as the number of turns, pitches, and offset rotation angles of the two helical antennas are studied. Then, a 2 × 2 dual-sense CP helical array antenna is developed by applying two sequentially rotated microstrip feeding networks on the same plane. To alleviate the congestion, the two feeding networks with 90-degree and 270-degree phase gradients are placed concentrically to excite RHCP and LHCP radiation, respectively. The dual-sense CP helical array antenna is prototyped and verified experimentally. Measured results agree well with the simulations, showing a wide overlapped impedance/3dB-AR bandwidth from 3.7-5.0 GHz (FBW = 30%) for both polarizations. The isolation is better than 22 dB over the frequency range.