Circularly Polarized Horn Antenna With Miniaturized Longitudinal Dimension for Vehicular Satellite Communications

A wideband circularly polarized (CP) horn antenna with miniaturized longitudinal dimension is proposed for satellite communications, by cutting a pair of antipodal tapered slots (ATSs) on the broad walls of the horn and loading simple metal blocks near the ATSs. By introducing a pair of ATSs, a linear cross polarization is generated with almost equal amplitude and quadrature phase relative to the original polarization, and a circular polarization is realized. Then the CP horn is longitudinally shortened by 33.3% for miniaturized dimension, but the circular polarization is deteriorated because the two linear polarizations are perturbed. Critically, three pairs of simple metal blocks introducing extra capacitances are loaded near the ATSs to enhance the cross polarization, so the two orthogonal linear polarizations are rebalanced and the circular polarization is reconstructed. Other two pairs of metal blocks are embedded on the throat of the horn to improve the impedance match on the operating band, achieving a 32.8% bandwidth of 11.35-15.8 GHz for both impedance and axial ratio bandwidths. The proposed antenna is easy to be fabricated by standard mechanical manufacture process, showing a compact and low-cost candidate for vehicular satellite communications.