PIER Letters | PIER Journals

2025-01-11

PIER Letters

Vol. 124, 31-36, 2025

download: 33

A High-Performance, Thin, Circularly Polarized Microstrip Antenna for Compact Radar Systems

Palaniselvan Sundaravadivel, Sathiyapriya Thangavel, Gold Beulah Patturose Jegajothi, Rethinasamy Meenakshi, Dhanushkodi Siva Sundhara Raja and Rajesh Kumar Dhandapani

This paper presents a novel, thin, circularly polarized microstrip antenna optimized for radar applications, designed to operate within the 7.5-7.7 GHz frequency band. The antenna is compact, with overall dimensions of 1.97λ x 1.08λ x 0.0025λ (where λ is wavelength calculated at 7.5 GHz) printed on a flexible polyimide substrate, offering advantages in terms of mechanical flexibility and integration into conformal systems. Circular polarization is achieved with an axial ratio of less than 3 dB across the operating bandwidth, while a peak gain of 6.25 dBi ensures adequate signal strength for radar detection and communication. Performance improvements are realized by introducing inverted C-shaped slots in the radiating element, effectively manipulating the surface current distribution and enhancing polarization purity and radiation efficiency. A prototype of the antenna was fabricated and tested, with experimental results closely matching simulation data, confirming the reliability of the design methodology. The results demonstrate that the proposed antenna is highly suitable for compact radar systems, offering an optimal balance among size, performance, and fabrication simplicity.

A High-performance, Thin, Circularly Polarized Microstrip Antenna for Compact Radar Systems

2025-01-10

PIER Letters

Vol. 124, 23-29, 2025

doi:10.2528/PIERL24091204

download: 51

A Dual-Band Rectangular Spiral Antenna for S-Band Applications

Chilakala Lokanath Reddy, Kallakunta Ravi Kumar, Nalluri Venkateswarlu, Kota Mahesh Babu, Tottempudi Venkata Rama Krishna, Ambati Navya and Kantamaneni Srilatha

A compact size, dual band rectangular spiral antenna with an inset feed is simulated and tested for S-band applications. Feeding of an antenna is given through a 50 Ω microstrip transmission line. The proposed design consists of a rectangular spiral radiating patch in the top plane and a Z-shaped structure in the bottom plane. Ansoft HFSSv13 has been utilised to design the rectangular spiral antenna, and parametric analysis has been done to verify the characteristics of an antenna. The rectangular spiral antenna is fabricated by utilising chemical etching, and it is tested by utilising MS2037C Anritsu combinational analyzer. Reflection coefficients of -16.5 dB and -16.2 dB, and fractional bandwidths of 8% (2.35-2.55 GHz) and 6.7% (3.22-3.44 GHz) are obtained at 2.4 GHz and 3.3 GHz respectively. Maximum gains of 3.1 dBi and 3.34 dBi are obtained at the two resonating frequencies. Omnidirectional and dipole type radiation patterns are obtained for different values of θ and Φ. The rectangular spiral antenna occupies an area of 16 × 16 × 1.6 mm³, and it is fabricated by using FR4 material. Simulated results are in good agreement with the measured ones. These results make the antenna suitable for many Zigbee/IEEE 802.15.4-based wireless data networks that operate in the 2.4-2.4835 GHz band, and it is also suitable for a wide range of applications including FWA systems.

A Dual-band Rectangular Spiral Antenna for S-band Applications

2025-01-03

PIER Letters

Vol. 124, 17-21, 2025

doi:10.2528/PIERL24103001

download: 67

A Miniaturization Dual-Passband Microwave Filter Based on Load-Coupled Open Stub Lines

Xinying Sun, Chuicai Rong, Huajie Gao and Menglu Zhang

In this Letter, a miniaturized U-shaped microstrip filter based on a load-coupled open line is proposed. It is composed of a step impedance resonator and parallel coupled open stub line. Interfinger feed is used to enhance coupling. This configuration and coupled open stub lines form four transmission zeros between two passbands as part of open coupled stub lines to increased out-of-band rejection. The analysis of formation reason of transmission zero is conducted using lossless transmission line theory and even-odd mode analysis techniques. A filter operating at 2.53 GHz and 5.53 GHz is simulated and fabricated. The insertion loss of first passband is 1.30 dB, and return loss is -18.60 dB. The insertion loss of the second passband is 0.70 dB, and return loss is 22.89 dB. The out-of-band rejection is maintained below -20.00 dB. The final model size is 0.20λ_g x 0.23λ_g. The final physical measurement results confirm theoretical results.

A Miniaturization Dual-passband Microwave Filter Based on Load-coupled Open Stub Lines

2024-12-13

PIER Letters

Vol. 124, 9-16, 2025

doi:10.2528/PIERL24091702

download: 179

Performance Enhancement of Substrate Integrated Waveguide Antenna for Wi-Fi Applications

Srisudharshan Manikandan, Anbazhagan Vidya Linkkesh, Shankaragouda M. Patil and Venkatesan Rajeshkumar

A single-band, linearly polarized Substrate Integrated Waveguide (SIW) antenna is designed specifically for WLAN 802.11a applications. The SIW design consists of four rectangular slots adjacent to each other through the SIW wall, with appropriate rectangular patch elements inserted in the two vertical slots for bandwidth enhancement. The structure is optimized to radiate at a frequency of 5.22 GHz, resulting in linear polarization caused by the excitation of the TE110 mode. The simulated design offers a gain of 7.275 dBi and a bandwidth of 47 MHz. The radiation pattern of the proposed fabricated antenna is measured in test environments where it is found to be unidirectional. The proposed design is compact and minimal in complexity, offering a higher gain.

Performance Enhancement of Substrate Integrated Waveguide Antenna for Wi-Fi Applications

2024-12-06

PIER Letters

Vol. 124, 1-7, 2025

doi:10.2528/PIERL24091001

download: 141

Application of Machine Learning in Urban Base Station Placement for 5G Communications and Beyond

Irfan Farhan Mohamad Rafie, Soo Yong Lim and Michael Jenn Hwan Chung

Optimal placement of wireless base stations in urban areas allows for maximum coverage and performance whilst maintaining minimal cost. In this paper, we propose a novel machine learning approach to place base stations rapidly in an urban environment for 5G communications and beyond. This is a noteworthy approach as 5G, especially those that involve millimeter wave frequencies tend to require significantly higher number of base stations for any particular area, unlike their counterpart low frequencies where a small number of base station is suﬀicient to cover a good geographical area. Our machine learning empowered path loss model is developed to tackle this change in gameplay head-on, and it bridges the gap between empirical and ray tracing methods where we achieve accuracy closer to ray tracing yet at a significantly lower computation cost. Promising preliminary results are obtained, with a minimum coverage area of 80% with potential for future improvements.