96-GHz Complementary Split Ring Resonator for Thin Photoresist Film Thickness Characterization

Non-destructive thickness measurement offers a valuable feature for thin polymer-based applications in both industrial and medical utilization. Herein, we developed a novel, non-destructive, millimetre-wave WR-10 waveguide sensor for measuring a dielectric film layer on a transparent substrate. Complementary split-ring resonator (CSRR) was integrated on top of a customized WR10 waveguide and operated at 96 GHz. The thickness of the SU-8 layers, ranging from 3-13 μm, coated on a glass substrate was then examined using the resonant frequency shift. The thickness values obtained from this novel sensor strongly resemble the values obtained from standard surface profiler measurement method, with less than 5 % difference. Thus, our novel design offers a comparable accuracy with a better cost effectiveness when compare with an existing commercial instrument

An X-band Portable 3D-printed Lens Antenna with Integrated Waveguide Feed for Microwave Imaging

This paper presents a portable 3D-printed lens antenna fed by a standard rectangular waveguide at X-band for object classification. The proposed lens antenna can integrate with the standard rectangular waveguide without any additional assistant tools. A high impact polystyrene is used to design the 3D-printed hemispherical lens antenna by using the fused deposition modelling technique. This additive manufacturing gives several advantages including rapid prototyping, better cost and time effectiveness. Five lens radiuses, e.g., 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm, are investigated to increase the gain of the antenna. The optimum dielectric tapered transition dimensions are simulated and obtained by using the 3D EM Simulation tool CST Studio, resulting in the reflection coefficient (S 11 ) of five lens antennas better than -10 dB across the WR-90 band. From the simulation results, the lens radiuses of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm, provide the average realized gain of 12.9 dBi, 15.2 dBi, 16.7 dBi, 17.7 dBi, and 18.6 dBi, respectively. To confirm the antenna performances of the proposed design, two lens radiuses, e.g., 20 mm and 30 mm are selected to fabricate. The gains of the lens radius of 20 mm and 30 mm are 12.1 dBi, and 14.2 dBi, respectively. The half-power beamwidth (HPBW) of lens radius of 20 mm and 30 mm are approximately 35° and 24°, respectively. The proposed dielectric lens antenna also offers other advantages, such as ease of design, low fabrication and material cost, and ease of mount and un-mount with WR-90 waveguide flange. Moreover, the narrow HPBW of lens antenna fed by standard waveguide can be applied to improve the resolution of the imaging system

A Square Patch Partially Reflective Surface for Improving the Antenna Gain Characteristic of Low-Cost Dual Polarized Microstrip Antenna

This paper presents an improvement gain of a dual-polarized microstrip patch antenna by using the partially reflective surface (PRS). The PRS is designed from a 10×10 array patches structure, which is patterned on a 0.8-mm FR-4 substrate. A-dual-port fed by two SMA connectors, which is selected to use as the source of an experiment. The square metallic patch is used to design the PRS layer. The dimension of the square patch is 5 mm ×5 mm. The length of the square patch is varied from 3.0mm to 4.5 mm by step of 0.5 mm to investigate the reflection coefficients, e.g., magnitude response and phase response. Based on the simulated results, a 4.5-mm square patch provides the highest reflection coefficient of 0.53. To prove the design concept, the size of a square patch of 4.5 mm is selected to fabricate and measure the radiation pattern. At an operating frequency of 3.5 GHz, the maximum gain at the zero degrees is increased from 1.2 dBi to 4.96 dBi when compared without and with PRS

A Portable 3D-Printed Dielectric Lens Antennas for Liquid-Mixture Characterization

The Fused Deposition Modeling (FDM) method is utilized in this research to present dielectric lens antennas that were 3D printed. The ultra-wideband (UWB) stub antenna’s antenna characteristic is intended to be improved by the 3D-printed dielectric lens antennas. The proportion of ethanol in the liquid mixture sample is categorized using the transmission-line measuring technique. The device-under-test (DUT) is placed between two 3D-printed dielectric lens antennas. The glass bottle is filled with a 100-ml liquid sample and covered with a plastic cap. The 3D EM Simulation CST Studio is used to optimize the 10 mm gap between the dielectric lens antennas and the DUT. Six concentrations of the ethanol/water mixture, such as empty, 60%, 65%, 70%, and 80%, are measured to examine the measurement system. The measurement outcomes indicate the various S21 (transmission coefficient) levels between 9 GHz and 11 GHz. According to the trend of the suggested system, the level of the transmission coefficient, S21, will change downward when the proportion of ethanol is increased. Several better advantages, such as a non-destructive method, non-contact measurement, and support with a real-time monitoring system, are provided by the transmission-line measuring methodology using 3D-printed dielectric lens antennas

Non-Destructive pH Sensor Using Honeycomb Resonator for Liquid-Mixture Characterization

This paper presents a feasibility study of a pH sensor utilizing the microwave transmission technique within the CST Microwave Studio software. The resonator is designed based on the modified split ring resonator shape (SRR) by incorporating six segments in a circular shape. The proposed resonator shape resembles a honeycomb structure with a capacitive gap to enhance the electric field (E-field) distribution in its area. The operating frequency is set to the Industrial, Scientific, and Medical (ISM) band of 5.82 GHz. According to the simulation, the E-field demonstrates its maximum strength at the focused area, measuring 29,863 V/m. Consequently, this position is deemed suitable for selecting the sensing area for liquid-mixture detection. To investigate the performance of the proposed sensor, the industry model of a Teflon tube is imported and placed atop the focused honeycomb resonator. The performance of the proposed sensor is evaluated by modeling various liquid samples, adjusting electrical properties such as relative permittivity, εr, and loss factor. The simulated results indicate that the proposed sensor provides a satisfactory transmission coefficient, S21, response for classifying relative permittivity, εr, changes within the range of 1 to 81. However, for future development, the proposed sensor will undergo fabrication and further investigation to assess its performance in practical applications

A Controllable Planar Wideband Bandpass Filters using the Combination of Microstrip and Substrate Integrated Waveguide Structure

This paper presents a planar wideband bandpass filter using a combination of microstip structure and substrate integrated waveguide (SIW). To control the bandwidth of the wideband bandpass filter, the proposed filter is designed by cascading structure between the high pass filter and low pass filter characteristic. The SIW, which is a high pass filter characteristic, is designed to determine the lower cutoff frequency. Then, the microstrip, which is a and low pass filter characteristic, is designed to determine the higher cutoff frequency. To verify the concept of the proposed filter design, three wideband bandpass filters, e.g., 2–5 GHz, 3–5 GHz and 4–5 GHz, have been simulated and achieved, resulting in fractional bandwidth of 80%, 50% and 20%, respectively. To prove the simulated results, the 4–5 GHz wideband bandpass filter is selected to fabricate on the low-cost FR-4 substrate with a thickness of 1.6 mm. The results show that measured and simulated results are agreed well in the reflection and insertion responses

THz Photo-Polymeric Lens Antennas for Potential 6G Beamsteering Frontend

This paper presents a 3D-printed THz hemispherical lens antenna integrated with the open-ended rectangular waveguide at WR-10 band for antenna characteristics enhancement, e.g., gain and half-power beamwidth (HPBW). The digital light processing (DLP) technique, which is one of the famous 3D printing techniques, is chosen for fabricating the hemispherical lens antenna. The proposed design can be integrating the 3D-printed lens antenna without any extra assistant tools during assembly lens antenna with an open-ended WR-10 waveguide. In the simulation, the lens radiuses are investigated by varying from 2 mm to 5 mm in step with 1 mm. The optimum dimensions of the 3D-printed hemispherical lens antennas are obtained by using the 3D electromagnetic simulation tools. Based on the simulation results, at 90 GHz, the lens radiuses of 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, provide the maximum realized gain of 11.7 dBi, 13.1 dBi, 14.8 dBi, 15.8 dBi, and 16.3 dBi, respectively. The proposed technique gives many advantages, including ease of design, inexpensive material, low-cost fabrication process, rapid prototyping, etc. Moreover, the narrow HPBW and high gain of the proposed lens antenna can be applied to the 6G beamsteering frontend system

An Incorporated 3D-Printed Lens with Square Microstrip Patch Antenna for NaCl Solution Discrimination

This paper presents a 3D-printed hemispherical lens incorporated with a square patch microstrip antenna for liquid-mixture characterization. The proposed hemispherical lens antenna is designed, fabricated, and integrated with the microstrip patch planar antenna. An Acrylonitrile Butadiene Styrene (ABS) is selected to design the 3D-printed lens antenna by using the fused deposition modeling (FDM) method, due to available 3D-printed material in the laboratory. The optimum dimensions and shape of the hemispherical lens antenna are obtained by using the 3D EM Simulation CST Studio, which is used to investigate the characteristic of the antenna, e.g., gain, radiation pattern, and reflection coefficient. To characterize the liquid content in NaCl solution, the level of the transmission coefficient (S21) is detected. The proposed sensor system offers various preferable features, e.g., non-destructive method and non-contact measurement. Five liquid solutions under test (LUT), e.g., 5%, 10%, 15%, 20%, and 25% NaCl in the NaCl-aqueous solutions, are measured and performed to generate the extraction model. The proposed sensor also offers other advantages, e.g., real-time monitoring and no life-cycle limitation