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.
ZHANG Hongxi
,
WANG Pei
. An improved high efficiency low error substrate integrated waveguide wideband delay line[J]. Journal of University of Chinese Academy of Sciences, 2025
, 42(5)
: 677
-685
.
DOI: 10.7523/j.ucas.2023.034
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