High Frequency Systems Laboratory

04/12/2025

📢 HFS New Publication Alert!

We're excited to announce that our latest research is now published in MDPI Sensors: "Additively Manufactured Mechanically Tunable Cavity Resonator for Broadband Characterization of Liquid Permittivity"
The Challenge: Traditional cavity resonators are limited to single-frequency measurements, restricting their effectiveness in material characterization.
💡 Our Solution: A tunable cavity resonator that enables broadband characterization across multiple frequencies while maintaining the high accuracy cavity perturbation methods are known for.
🎯 Key Benefits:
* Characterize materials across a tunable frequency range, not just a single point.
* Particularly valuable for analyzing solutions at different concentrations with strong frequency dispersion
* Select optimal frequency ranges for maximum sensitivity
* Avoid measurement ambiguities caused by reverse signal trends

This work was made possible through our collaboration with the Materials and Production Engineering and
Materials for Energy Applications Group
📖 Read the full paper using the link provided:

HFS publication post statement: We share posts like this to acknowledge our team’s dedication and to highlight work that may benefit others. Every real achievement comes from long hours, uncertainty, limited resources, and the courage to keep going when the path is unclear.
To PhD students, postdocs, and early-career researchers: you are the backbone of our scientific community. When anxiety arises, seek strength from those who care about you.
Keep moving, keep learning, and trust in the value of your work. We look forward to celebrating your success soon.

This paper presents the design, fabrication, and experimental validation of a metal 3D-printed mechanically tunable cavity resonator operating in the hybrid TM–coaxial resonant mode for the broadband characterization of liquid permittivity. The proposed structure was developed based on a cylindric...

14/11/2025

HFS Publication Alert 📢

The early-access version of our paper, “Capacitance Characteristics of Glass-Embedded Interdigitated Capacitors for Touch Sensing Applications,” is now available in MDPI Sensors.

We are pleased to share the results of this research, conducted in collaboration with our long-term industrial partner, Thai Technoglass Group PLC.

Our proposed capacitive sensor design framework provides practical guidelines for how sensor designers can adjust structural dimensions and overlay materials to achieve the desired sensitivity—supporting the vision of transforming everyday surfaces into interactive interfaces.

A quick search on IEEE Xplore for building glass embedded capacitive sensors will show our work among the very first contributions in this area.

Read the paper here:

HFS publication post statement: We share posts like this to acknowledge our team’s dedication and to highlight work that may benefit others. Every real achievement comes from long hours, uncertainty, limited resources, and the courage to keep going when the path is unclear.
To PhD students, postdocs, and early-career researchers: you are the backbone of our scientific community. When anxiety arises, seek strength from those who care about you.
Keep moving, keep learning, and trust in the value of your work. We look forward to celebrating your success soon.

This paper investigates the capacitance characteristics of a glass-embedded interdigitated capacitive sensor (IDCS) for touch-sensing applications. The study analyzes both baseline (no-touch) and touch-induced capacitance variations through a combination of analytical modeling and experimental valid...

29/10/2025

We were delighted to welcome researchers from PTT Innovation Institute on October 27th to explore exciting possibilities in green, flexible and wearable electronics. PTT has developed innovative conductive ink with promising properties, and our HFS lab will investigate its potential applications in antennas, sensors, and semiconductors. We are looking forward to this collaboration.

29/08/2025

HFS Lab and SIIT collaborate on materials for green electronics.

Today, our lab welcomed Hasini, a PhD researcher supervised by Prof. Shu-Han Hsu from Sirindhorn International Institute of Technology (SIIT), who came to deliver material samples and discuss the electrical characterization of alternative materials for green and sustainable electronics. This collaboration aims to tackle the problem of electronic waste harming the environment. The alternative materials—both conductive and dielectric—should be environmentally friendly while still offering excellent electrical properties for IoT and other electronic devices.

Sirindhorn International Institute of Technology, Thammasat University, and the Sirindhorn International Thai-German Graduate School of Engineering, KMUTNB, are separate institutions with similar names. But beyond the names, we also share close collaboration in research projects. One of these works has already received the Best Paper Award at Thailand’s flagship electrical engineering conference, ECTI-CON 2025.

29/08/2025

HFS Weekend Post.

Today, HFS PhD candidate Muhammad Uzair successfully passed his progress examination. With his extensive research on alternative materials for glass-based and green electronics, the examination committee praised his work as being of very high standard, and recommended him to finalize the antenna design with the selected materials for the final stage of his PhD thesis. He is well on his way to an outstanding PhD. Keep it up, Muhammad—just one last step toward an important academic milestone!

21/08/2025

Our Latest Research on Metasurface-Integrated Mobile Phone Case Published

A collaborative work of our HFS lab with Assoc. Prof. Dr. Juin Acharjee from St. Thomas’ College of Engineering and Technology, Kolkata, India, has been published in Wireless Personal Communications (Scopus Q1, Springer Nature). The paper, titled “Dual-Broadband Metasurface Printed on Mobile Phone Back Cover for Enhanced Antenna Performance and SAR Reduction”, explores the use of a mobile phone case with an integrated metasurface to enhance antenna performance while reducing the specific absorption rate (SAR) in a human head model. Our lab would like to thank all co-authors and partners for this fruitful collaboration.

Access to the publication is subscription-based. If your institution subscribes to Springer Nature, you can access the paper via the link provided.

https://link.springer.com/article/10.1007/s11277-025-11803-6?utm_source=rct_congratemailt&utm_medium=email&utm_campaign=nonoa_20250821&utm_content=10.1007/s11277-025-11803-6

10/08/2025

This work by HFS Lab's PhD student Thipamas Phakaew has been published in the IEEE Open Journal of Antennas and Propagation. It is a pioneering effort that uses radar technology to prevent accidents involving trains and other vehicles or pedestrians.

The research is the result of a collaboration with Prof. Thomas Dallmann, Head of the Radio Technologies for Automated and Connected Vehicles Research Group at the Technical University of Ilmenau in Germany, and NECTEC NSTDA.

At HFS, we are committed to developing technologies that improve quality of life. This study also includes experiments in realistic scenarios, demonstrating its potential for real-world applications.

[A Wideband 4×4 Patch Array Antenna With Low Sidelobes for Radar-Based Obstacle Detection in Railway Transportation]

Thipamas Phakaew, Tiwat Pongthavornkamol, Danai Torrungrueng, Thomas Dallmann and Suramate Chalermwisutkul presents the design, fabrication, and measurement of a 4×4 patch array antenna for radar-based obstacle detection systems in railway transportation. Sidelobe suppression is achieved through amplitude tapering of sub-array elements in the E-plane and asymmetric power dividers in the feed network for the H-plane. The array antenna is framed by a coplanar ground conductor to further reduce sidelobes and fed by a coplanar waveguide port for enhanced impedance bandwidth. The proposed antenna offers an impedance bandwidth from 9.13 GHz to 9.76 GHz (6.3%) and a broadside gain of 18.15 dBi at the center frequency of 9.55 GHz. Sidelobe suppression exceeds 12.22 dB and 19.06 dB in the E- and H-plane, respectively.

Read their article here: https://ieeexplore.ieee.org/document/10912488/

10/08/2025

HFS Weekend Post, Publication Alert:

The work of HFS lab's PhD student Muhammad Uzair titled "Design and Characterisation of All-Dielectric Metasurface Reflector for mmWave Antennas" is now published in IET Microwaves, Antennas & Propagation. This is a result of our lab's long-term collaboration with the Institute of High Frequency Technology IHF, RWTH Aachen University in Germany. The paper reports a concept of using structured dielectric material as a zero-phase reflector for antennas, e.g., for automotive radar applications.

The proposed all-dielectric AMC is promising compared to AMCs with electric conductor structures, which are prone to losses due to surface roughness at the mmWave regime. We are grateful for the great collaboration with IHF and will continue to jointly contribute to the antenna and propagation community. The article can be accessed with the link provided.

This study presents an all-dielectric artificial magnetic conductor (AMC) operating at 77 GHz with zero-phase reflection, featuring a −1-dB reflection bandwidth of 3.6 and 8.2 GHz for ± 45° and ± 90°...

05/08/2025

Another milestone at HFS.

Today, Intira (Irene), an application engineer from CADFEM — a long-term channel partner of the simulation software company Ansys — joined our HFS lab as an external researcher. With her strong expertise in Ansys simulation, this marks the first academic–industry collaboration of its kind for our lab.

Together, CADFEM and HFS will co-develop content on electromagnetic, antenna, and high-frequency simulations, and work hand-in-hand to address real industrial challenges in the Thai ecosystem.

Welcome to HFS lab, Irene!

(It’s amazing—HFS just needs one more S to become HFSS 😄)

27/07/2025

🥈 Glassense Project Wins Innovation Award! 🏆✨

We're proud to announce that “Glassense: Smart Glass with Embedded Touch Sensor” has won Second Runner-Up at the KMUTNB Invention and Innovation Contest 2025!

This exciting project reimagines laminated glass as an interactive touch-enabled surface — a game-changer for smart buildings and urban interfaces. 💡

Team Members:
– Assoc. Prof. Dr. Suramate Chalermwisutkul
– Asst. Prof. Dr. Kittisak Paebua
– Mr. Alexander Dressler
– Mr. Apichat Kaewcharoen
– Mr. Muhammad Uzair

Big thanks to the team and supporters behind this innovation. This is just the beginning for Glassense and our mission to shape the future of smart materials and embedded sensing!