本文运用场匹配法对具有任意位错的双排矩形栅慢波结构的场分布、色散特性及耦合阻抗进行了研究.研究结果表明,场匹配法推导的色散特性与仿真软件CST和HFSS计算的结果完全一致,耦合阻抗介于CST和HFSS之间.在此基础上,详细研究了上下两排系统之间位错对色散特性及耦合阻抗的影响.当位错严格为半个周期时,第一阻带消失,第一个模式最高截止频率与第二个模式最低截止频率重叠,发生简并;当位错为0.45倍周期时,在保证耦合阻抗不变的情况下,基模的通带虽降低了2.8GHz,但阻带却增大了7.9GHz,从而可以有效避免简并及模式竞争的发生.
A mode analysis is presented for the double-grating rectangular waveguide slow-wave structure (SWS) with arbitrary longitu- dinal displacements between the two gratings. By matching boundary conditions along the sides of the gratings, the distribution of electromagnetic field and high frequency characteristics of the SWS are studied. The simulation results show that the dispersion curve deduced from field equations is in good agreement with that simulated by software while the interaction impedance is higher than that calculated by HFSS, but lower than by CST. It also demonstrates that the longitudinal displacement between two gratings has a great effect on the first stop-band. The upper cutoff frequency of the first mode almost overlaps the lower cutoff frequency of the second mode when the displacement is set to be strictly half period, that is to say, the first stop-band disappears. To avoid the mode degeneracy and competition, the displacement is reduced to be about 0.45 times of period, so that with the interaction impedance kept unchanged, the stop-band increases about 7.9GHz, while the pass-band declines about 2.8 GHz.