| The radiation of leaky wave antenna based on composite right left-handed trans-mission line is realized due to the theory of fast wave. The antenna’s phase shift con-stant varies from positive value to negative value continuously as the working frequencychanges, so main lobe direction of the antenna varies accordingly. Once lumped elementsare utilized, beamforming at fixed frequency can be realized by applying various DC bi-ases. The existing literatures always focus on the study of scanning range and workingfrequency but the polarization is seldom mentioned. In this paper, a novel2D circularly-polarized leaky wave antenna array is presented based on CRLH transmission line withacceptable axial ratio and return loss.First, studies on the principle of the CRLH LW antenna radiation are carried out andthe equivalent lumped circuit element values are extracted and the LW antenna array isdesigned which radiates from backfire to endfire. With the employment of varactor diodesbeamforming at fixed frequency is realized.Second, the circularly-polarized unit cell is designed. Consider that the via holewhich supplies left-handed character will modify the surface current, a novel unit cell ispresented to maintain the circularly-polarized feature in the scanning range. And a novelDC bias is designed,too.Third, the Blouch Impedance is studied as it is modified when the DC bias varies. Aimpedance matching network is designed to ensure that the return loss is below-10dB.Finally, the linear array is extended to a2D array. The return loss and axial ratio isstudied. |
PDF Full Text Request