Polymer-Based Micromachining for Scalable and Cost-Effective Fabrication of Gap Waveguide Devices Beyond 100 GHz
Doctoral thesis, 2023

The terahertz (THz) frequency bands have gained attention over the past few years due to the growing number of applications in fields like communication, healthcare, imaging, and spectroscopy. Above 100 GHz transmission line losses become dominating, and waveguides are typically used for transmission. As the operating frequency approaches higher frequencies, the dimensions of the waveguide-based components continue to decrease. This makes the traditional machine-based (computer numerical control, CNC) fabrication method increasingly challenging in terms of time, cost, and volume production. Micromachining has the potential of addressing the manufacturing issues of THz waveguide components. However, the current microfabrication techniques either suffer from technological immaturity, are time-consuming, or lack sufficient cost-efficiency. A straightforward, fast, and low-cost fabrication method that can offer batch fabrication of waveguide components operating at THz frequency range is needed to address the requirements.

A gap waveguide is a planar waveguide technology which does not suffer from the dielectric loss of planar waveguides, and which does not require any electrical connections between the metal walls. It therefore offers competitive loss performance together with providing several benefits in terms of assembly and integration of active components. This thesis demonstrates the realization of gap waveguide components operating above 100 GHz, in a low-cost and time-efficient way employing the development of new polymer-based fabrication methods.

A template-based injection molding process has been designed to realize a high gain antenna operating at D band (110 - 170 GHz). The injection molding of OSTEMER is an uncomplicated and fast device fabrication method. In the proposed method, the time-consuming and complicated parts need to be fabricated only once and can later be reused.

A dry film photoresist-based method is also presented for the fabrication of waveguide components operating above 100 GHz. Dry film photoresist offers rapid fabrication of waveguide components without using complex and advanced machinery.

For the integration of active circuits and passive waveguides section a straightforward solution has been demonstrated. By utilizing dry film photoresist, a periodic metal pin array has been fabricated and incorporated in a waveguide to microstrip transition that can be an effective and low-cost way of integrating MMIC of arbitrary size to waveguide blocks.

Dry film photoresist

Terahertz frequency

Injection molding

MEMS

mmWave

Gap waveguide

Antenna

Waveguide

Polymer microfabrication

Kollektorn, MC2
Opponent: Dr. Goutam Chattopadhyay NASA Jet Propulsion Laboratory California Institute of Technology Pasadena, California, United States

Author

Sadia Farjana

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems

Realizing a 140 GHz Gap Waveguide–Based Array Antenna by Low-Cost Injection Molding and Micromachining

Journal of Infrared, Millimeter, and Terahertz Waves,;Vol. 42(2021)p. 893-914

Journal article

Low Loss Gap Waveguide Transmission line and Transitions at 220-320 GHz Using Dry Film Micromachining

IEEE Transactions on Components, Packaging and Manufacturing Technology,;Vol. 11(2021)p. 2012-2021

Journal article

Micromachined Wideband Ridge Gap Waveguide Power Divider at 220-325 GHz

IEEE Access,;Vol. In Press(2022)

Journal article

Micromachined Low-Loss Transition from Waveguide-to-Microstrip Line for Large MMIC Integration and Packaging at 250 GHz , submitted to IEEE Transactions on Terahertz Science and Technology

The terahertz (THz) frequency band (100 GHz–10 THz) has gained significant attention over the past few years due to the growth of applications in different fields. Above 100 GHz the losses in transmission lines become problematically high, and waveguides are used for the transmission of signals. The dimensions of the waveguide-based components continue to decrease as the frequency increases, and this makes traditional machine-based (computer numerical control, CNC) fabrication increasingly challenging in terms of accuracy, time, cost, and volume production. Micromachining has the potential of addressing the above-mentioned issues. Still, the current microfabrication techniques either suffer from technological immaturity, are time-consuming, or are costly. A straightforward, fast, and low-cost fabrication method that can offer batch fabrication of waveguide components operating at THz frequency is required. This thesis proposes two different fabrication methods focusing on high fabrication accuracy, fewer fabrication steps, less fabrication time, batch production, and low cost. The proposed template-based injection molding process can fabricate devices ⁓10 times faster than the conventional micromachine methods. The proposed SUEX dry film photoresist-based method can overcome the complications of liquid photoresists and offers a straightforward method of volume production, with fewer processing steps and without the requirement of using sophisticated fabrication tools and an advanced laboratory environment.

Areas of Advance

Nanoscience and Nanotechnology

Subject Categories

Electrical Engineering, Electronic Engineering, Information Engineering

Nano Technology

Infrastructure

Nanofabrication Laboratory

ISBN

978-91-7905-845-6

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5311

Publisher

Chalmers

Kollektorn, MC2

Online

Opponent: Dr. Goutam Chattopadhyay NASA Jet Propulsion Laboratory California Institute of Technology Pasadena, California, United States

More information

Latest update

5/5/2023 7