Design and Cold-Test Study of W-Band Suspended Array Ring-Rod Dual-Channel Integrated Microstrip Meander Line Slow Wave Structure

This article presents a suspended array ring-rod microstrip meander-line SWS (SARR-MML SWS), developed from the suspended ring-rod microstrip meander line SWS (SRR-MML SWS). The proposed configuration combines two SRR-MML traveling-wave tube (TWT) units through microstrip power dividers to enable efficient power combining. High-frequency simulations were performed in CST Microwave Studio to systematically analyze and characterize the high-frequency properties and electric field distributions of both the proposed SARR-MML SWS and the conventional single-channel SRR-MML SWS. Particle-in-cell (PIC) simulations systematically assessed the impact of interchannel spacing$d$on output power, operational stability, saturation power, gain, and electronic efficiency. Under a 10-kV beam voltage, 263-A/cm2current density, and 9.0-mm interaction length, the SARR-MML TWT achieves a saturation output power at 97 GHz that is 5251% higher than the single-channel design, confirming effective power combining under full coupling between channels. With a 10-W input power, the output reaches 166.66 W, corresponding to a gain of 12.21 dB and an electronic efficiency of 4.16%, along with a 3-dB saturation bandwidth of 92–100 GHz, indicating broad operating bandwidth. The SARR-MML SWS was fabricated via photolithography and validated through cold-test measurements, which showed a reflection coefficient S$11\lt -143$dB and transmission coefficient S21 between −3.7 and −5.1 dB across 90–100 GHz, in good agreement with simulations, thereby affirming the reliability of the integrated design.