Broadband Differential-Line-to-Waveguide Transition in Multi-Layer Dielectric Substrates With an X-Shaped Patch Element in 280 GHz Band

Abstract

A broadband differential-line-to-waveguide transition covering the 260-300 GHz band was developed in this study. This transition consists of a differential line inserted from the narrow wall of the waveguide that excites an X-shaped patch located at the waveguide center. As the two corners of the patch are excited electromagnetically via differential signal lines in the opposite phase, orthogonal current components that radiate the TE 10 mode into the waveguide are generated. Broadband operation is achieved via the double resonance of the X-shaped patch and a cavity formed by the via-hole arrangement with apertures patterned in a multi-layer substrate. The transition geometries are optimized via electromagnetic simulation using a finite element method. Transition performance is evaluated through measurements and simulations.

Broadband Waveguide-to-Differential-Line Transition in Multi-Layer Substrates With Triple Stacked Patch in 300 GHz Band

“…Therefore, comparisons with the most similar methods are provided to evaluate the effectiveness of this paper, focusing mainly on the waveguide-to-differential-line transitions [39]- [43], but the bandwidth is still not wide. For [49], the bandwidth of the reflections less than −10 dB was 66.3 GHz (23.6%) and the measured transmission coefficient for the single transition was −2.6 dB at 275 GHz. For this work, the frequency bandwidth of 100 GHz (37.0%) at the reference S11 below −10 dB was consistent with the waveguide standard of WR-3.…”

“…A study focused on investigating losses in transmission line structures on package substrates tailored for the 100 GHz to 300 GHz frequency range. The performance of these transmission lines was evaluated through a combination of analytical and experimental methods, as implemented in [49], [54]. To obtain the transmission loss of the differential line, transitions with back-to-back configurations connected by differential lines of different lengths were fabricated as shown in Fig.…”

“…Therefore, there remains a challenge for existing designs to achieve broadband in terahertz band. A comparison with our previous work [49], the transition using a differential line inserted from the narrow wall of the waveguide and multiresonance of the X-shaped patch used for broadband operation. However, the bandwidth was insufficient to fully cover the WR-3 band.…”

“…Many techniques, such as aperture excitation, have been applied to waveguides [44]. Broadband techniques have been developed using waveguide taper [45], back-short structure [46], fin-line taper [47], unilateral substrateless finline structure [48], and differential line inserted from the narrow wall of the waveguide with X-shaped patch [49]. In addition, the development of this transition depends on its implementation in applications.…”