为克服高分辨率星载合成孔径雷达相控阵天线系统中的波束色散问题，设计了一种X波段宽带真时间延迟线。该延迟线通过在基片集成波导的上表面加载电磁带隙结构形成。这相当于增加了单位长度上的电感电容，实现了慢波效应。还引入了一种微带线-SIW锥形过渡结构，在大带宽情况下实现了低损耗。实测结果表明，在8~12 GHz频段，延迟倍数达到4倍，即延迟线的延迟时间是相同长度50 Ω微带线的4倍。此外，延迟波动，即最大和最小延迟量之差仅占设计延迟量的2.5%，插入损耗优于-2.5 dB，回波损耗优于-15 dB。与现有延迟线相比，所提出的延迟线具有延迟效率高、延迟误差小、带宽大、损耗低的优点，具有良好的实用价值和应用前景。
关键词：
SIW; EBG; 低损耗; 高效; 宽带
In this paper, a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system. The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide. This is equivalent to including an additional inductance-capacitance for energy storage, which realizes the slow-wave effect. A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth. In the frequency band between 8-12 GHz, the measured results show that the delay multiplier of the delay line reaches 4 times, i.e., delay line’s delay time is 4 times larger than 50 Ω microstrip line with same length. Furthermore, the delay fluctuation, i.e., the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%, the insertion loss is less than -2.5 dB, and the return loss is less than -15 dB. Compared with the existing delay lines, the proposed delay line has the advantages of high delay efficiency, low delay error, wide bandwidth and low loss, which has good practical value and application prospects.
[1] Frankel M Y, Matthews P J, Esman R D. Fiber-optic true time steering of an ultrawide-band receive array[J]. IEEE Transactions on Microwave Theory and Techniques, 1997, 45(8): 1522-1526. DOI: 10.1109/22.618469.
[2] Reindl L, Ruppel C C W, Berek S, et al. Design, fabrication, and application of precise SAW delay lines used in an FMCW radar system[J]. IEEE Transactions on Microwave Theory and Techniques, 2001, 49(4): 787-794. DOI: 10.1109/22.915465.
[3] Hui W, Li S L. New design of delay line based on slow-wave structure[C]//2017 4th International Conference on Information Science and Control Engineering (ICISCE). July 21-23, 2017, Changsha, China. IEEE, 2017: 1556-1558. DOI: 10.1109/ICISCE.2017.324.
[4] Caloz C, Itoh T. Transmission line approach of left-handed (LH) materials and microstrip implementation of an artificial LH transmission line[J]. IEEE Transactions on Antennas and Propagation, 2004, 52(5): 1159-1166. DOI: 10.1109/TAP.2004.827249.
[5] Uchimura H, Takenoshita T, Fujii M. Development of a “laminated waveguide”[J]. IEEE Transactions on Microwave Theory and Techniques, 1998, 46(12): 2438-2443. DOI: 10.1109/22.739232.
[6] Zhou Y L, Jin H Y, Huang Y M, et al. Slow-wave effect enhanced substrate integrated waveguide with multi-antipodal blind via-holes and distributed metal strips[J]. IEEE Microwave and Wireless Components Letters, 2020, 30(8): 753-756. DOI: 10.1109/LMWC.2020.3004236.
[7] Jin H Y, Wang K D, Guo J P, et al. Slow-wave effect of substrate integrated waveguide patterned with microstrip polyline[J]. IEEE Transactions on Microwave Theory and Techniques, 2016, 64(6): 1717-1726. DOI: 10.1109/TMTT.2016.2559479.
[8] Xu F, Wu K. Guided-wave and leakage characteristics of substrate integrated waveguide[J]. IEEE Transactions on Microwave Theory and Techniques, 2005, 53(1): 66-73. DOI: 10.1109/TMTT.2004.839303.
[9] Li D, Tong C M, Bao J S, et al. A novel bandpass filter of substrate integrated waveguide (siw) based on s-shaped ebg[J]. Progress in Electromagnetics Research Letters, 2013, 36: 191-200. DOI: 10.2528/pierl12110202.
[10] Deslandes D. Design equations for tapered microstrip-to-Substrate Integrated Waveguide transitions[C]//2010 IEEE MTT-S International Microwave Symposium. May 23-28, 2010, Anaheim, CA, USA. IEEE, 2010: 704-707. DOI: 10.1109/MWSYM.2010.5517884.
[11] Deslandes D, Wu K. Integrated microstrip and rectangular waveguide in planar form[J]. IEEE Microwave and Wireless Components Letters, 2001, 11(2): 68-70. DOI: 10.1109/7260.914305.
[12] Deslandes D, Wu K. Analysis and design of current probe transition from grounded coplanar to substrate integrated rectangular waveguides[J]. IEEE Transactions on Microwave Theory and Techniques, 2005, 53(8): 2487-2494. DOI: 10.1109/TMTT.2005.852778.
[13] Zhang J, Cheung S W, Yuk T I. Compact composite right/left-handed transmission line unit cell for the design of true-time-delay lines[J]. IET Microwaves, Antennas & Propagation, 2012, 6(8): 893. DOI: 10.1049/iet-map.2011.0579.
[14] Liu Z Q, Xia H Y, Liu H, et al. Slow wave gap waveguide with bandpass filtering functionality[J]. IEEE Microwave and Wireless Components Letters, 2022, 32(8): 953-956. DOI: 10.1109/LMWC.2022.3162610.
[15] Deng J Y, Wang Z J, Sun D Q, et al. Slow-wave substrate integrated groove gap waveguide[J]. IEEE Microwave and Wireless Components Letters, 2020, 30(5): 461-464. DOI: 10.1109/LMWC.2020.2983017.
[16] Ghazizadeh M H, Medi A L. Novel trombone topology for wideband true-time-delay implementation[J]. IEEE Transactions on Microwave Theory and Techniques, 2020, 68(4): 1542-1552. DOI: 10.1109/TMTT.2019.2959319.
