Designs Of Endfire Antenna Based On Spoof Surface Plasmon Polaritons And Coplanar Stripline

Spoof Surface Plasmon Polaritons(SSPPs)are surface waves with dispersity and high field confinement that excited on periodically metal surface.This paper includes several researchs and designs of endfire antennas and arrays based on SSPPs and coplanar stripline(CPS).The contents are outlined as below:(1).A wideband endfire antenna based on spoof surface plasmon polaritons(SSPPs)is proposed.The SSPPs is supported by dipole-shaped unit cells.Since the introduction of phase reversal crossover,the ordinary antenna is segment to two sections SSPPs with half-length that make up a two-element array.The endfire directivity of the proposed modified SSPPs antenna is enhanced due to the extra phase added by the phase reversal crossover.It achieves 67% relative bandwidth from 4 to 8 GHz.The maximum measured endfire gain attains 7.9 d Bi.(2).A wideband and high-gain planar endfire antenna based on SSPPs at millimeter-wave(MMW)band is presented.First,a unilaterally corrugated surface antenna is demonstrated to radiate endfire beam tilted up from the flat plane of corrugated metal teeth due to the effect of finite ground plane.Then,a SSPPs endfire antenna is designed with two symmetrically corrugated surfaces on the double sides of a metal strip.To excite the desired beam,the feeding network is comprised by a power divider and two L-shaped slots,so as to simultaneously produce oppositely tangential electric fields and identically normal electric fields.Moreover,the two equivalent identically tangential magnetic current sources above the corrugated surfaces are excited by flared feeding slot transitions.As a result,a synthetic endfire beam with zero tilted angle is achieved.In final,such an antenna,operating in a range from 30 to 50 GHz with 50% fractional bandwidth,is designed with maximum gain 16 d Bi.(3).A compact endfire CPS antenna is presented.A design method to achieve the endfire radiation based on CPS short ended structure is proposed.By short ending both sides of the CPS,the two shorted-edges realized an endfire radiation.The current vectors on the two shorted-edges are out-ofphase,thus the two shorted-edges make up a two-element endfire array by choosing a separation distance condition of half-wavelength in free space.The endfire CPS antenna realizes maximum gain of 4.02 d Bi at the center frequency of 6.32 GHz.(4).To increase the directivity of the CPS endfire antenna in(3),six CPS elements of onewavelength are cascaded by using phase reversal crossover,which make up an ordinary 6-elements endfire array.A phase reversal crossover can be equivalent to electric dipole while lead to 180 degree phase difference in transmission line.Therefore,the phase difference of the element of the array is achieved 180 degree.As a result,the endfire CPS array realizes maximum gain of 7.45 d Bi at the frequency of 6.45 GHz.(5).Since the directivity of the ordinary array in(4)is not largest,the Hansen-Woodyard condition is introduced to design a directivity-enhanced array.Meanwhile,a microstrip line-CPS transition balun and a quarter-wavelength impedance transition is used to increase the bandwidth of the array.The directivity-enhanced array achieves 28% relative bandwidth from 5.68 to 7.54 GHz.The maximum endfire gain attains 12.8d Bi.The proposed antennas in this paper are analyzed in theory and verified experimentally.Moreover,the antennas are low-profile and easy-fabricated with planar circuits.