Fabrication of new micromachined transmission line with dielectric posts for millimeter-wave applications

Abstract

This paper describes a new GaAs-based surface-micromachined microstrip line supported by dielectric posts and with an air gap between the signal line and the ground metal. This new type of dielectric post and air-gapped microstripline (DAML) structure was developed using surface micromachining techniques to provide an easy means of air-bridge connection between the signal lines and to achieve low losses in the millimeter-wave frequency band with a wide impedance range. Each DAML is fabricated with a length of 5 mm. By elevating the signal lines from the substrate using micromachining technology, the substrate dielectric loss can be reduced. Compared with conventional microstrip transmission lines, which show over 10 dB cm−1 loss, the loss of a DAML can be reduced to 1.1 dB cm−1 at 50 GHz.

Micromachined rectangular-coaxial transmission lines

“…Custom processes are available either through in-house development or at several universities [16]- [20], [44]- [46]. In addition, the Defense Advanced Research Projects Agency (DARPA) 3-D microelectromagnetic RF systems (MERFS) program aims to develop a low-cost multilayer process utilizing copper as the structural material.…”

“…Over the past several years, work has progressed on the fabrication of transmission lines using electroplated films on top of the substrate, leading to the realization of suspended CPW transmission lines [16]- [20] and recta-coax lines [18]- [26]. Demonstrations of couplers and filters at microwave frequencies have shown the potential for these lines to simplify the design of millimeter-wave systems [21], [23]- [26].…”

A novel V‐band 90° hybrid using surface micromachining technology

“…In this paper, we utilize a novel microstrip line, dielectricsupported air-gapped microstrip line (DAML), which was pre-sented in [7], in order to reduce the loss at millimeter-wave and fabricate an integrated passive circuit using the conventional MMIC. The proposed novel multisectioned microstrip line hybrid consists of parallel coupled lines and symmetrical delay lines, as depicted in Figure 1, and exhibits tight coupling at the center frequency of 60 GHz.…”