招待講演

海外講師をお招きして招待講演を開催いたします。（※聴講は大会参加登録が必要です）

■日　時：9月18日(木)　14:40～15:10

■会　場：第11会場　[4階]A44講義室　　（論文番号　05-1P-01）

■開催セッション

International Session (1) Electromagnetic Waves and Antennas
国際セッション(1)（電磁波・アンテナ）

■共　催：IEEE Antennas and Propagation Society Fukuoka Chapter

■講　師：Prof. Jaward Y. Siddiqui （Royal Military College of Canada）

■講演概要
This work discusses the design of reconfigurable ultra-wideband (UWB) antennas exhibiting dual complementary characteristics such as a frequency-notched UWB response and a narrowband response. The key innovation lies in integrating a reconfigurable filter section composed of Split Ring Resonators (SRRs) onto the feed line of printed ultrawideband antennas.

Modern RF systems often require multiple antennas to support various frequency bands. Reconfigurable antennas address this need by providing frequency agility, compact size, and reduced hardware complexity. The proposed antenna achieves this through electrical reconfiguration enabled by the embedded SRRs and PIN diodes.

The techniques proposed in this work have been implemented on two types of UWB antennas, a printed monopole antenna [1]-[4] and a printed antipodal tapered slot antenna (ATSA) [5] to validate the concept on radiators with distinct radiation characteristics: omnidirectional and directional, respectively. In both cases, split ring resonators (SRRs), magnetically coupled to the CPW feed line, function as band-stop filters, introducing a frequency notch in the UWB response around their resonance. When a set of PIN diodes embedded in the feed line are forward biased (ON), the antenna transforms into a narrowband band-pass filter centered at the same resonance frequency, thereby realizing complementary frequency responses from a single antenna structure [6].

A key feature of the design is that it preserves the original radiator geometry. The SRRs are symmetrically positioned on the reverse side of the substrate, aligned precisely with the CPW slot gaps to ensure optimal magnetic coupling. The dual-state filter section was initially characterized independently, and measured S-parameters confirmed its intended functionality in both biasing conditions.

Radiation measurements of the monopole antenna revealed an omnidirectional pattern across the UWB band, with a distinct gain drop at the notch frequency in the diode OFF state. In the narrowband mode (diode ON), the antenna exhibited a peak gain of 3.59 dBi at the resonance frequency, consistent with a band-pass response [6]. In the case of the SRR-loaded ATSA, the directional radiation patterns remained consistent with the unloaded antenna across the operational band, except near the notch frequency, where expected dips were observed [5].

The study also demonstrated frequency tunability by adjusting the physical dimensions of the SRRs. Both the notch and passband frequencies shifted predictably with changes in geometry, offering customization flexibility without altering the radiator. Furthermore,

simulation of Poynting vector contours provided valuable physical insight into the behavior of electromagnetic energy propagation within the CPW-SRR structure. These plots illustrated how energy is either selectively blocked or transmitted based on the diode biasing, reinforcing the complementary nature of the antenna’s dual-state operation.

In conclusion, this work demonstrates a compact, versatile, and effective approach to achieving multifunctionality in UWB antennas. The integration of reconfigurable filtering into the feedline enables real-time switching between wideband and narrowband operation, making the design especially suitable for cognitive radio, multi-standard wireless systems, and MIMO applications. The modular nature of the filter also allows for easy adaptation to other printed antenna types.

References:

[1] J.Y. Siddiqui, C. Saha and Y.M.M. Antar, "Compact SRR Loaded UWB Circular Monopole Antenna with Frequency Notch Characteristics," IEEE Transactions on Antennas and Propagation, Vol. 62, no. 8, pp. 4015-4020, 2014

[2] J.Y. Siddiqui, C. Saha and Y.M.M. Antar, "Compact Dual SRR Loaded UWB Monopole Antenna with Dual Frequency and Wideband Notch Characteristics," IEEE Antennas and Wireless Propagation Letters, Vol. 14, pp. 100 - 103, 2015

[3] C. Saha, J.Y. Siddiqui and Y.M.M. Antar, “A Novel Ultra Wideband (UWB) Printed Antenna with a Dual Complementary Characteristic” IEEE Antennas and Wireless Propagation Letters, vol. 14 pp. 974-977,2015.

[4] L. Ahmed, C. Saha, Y.M.M. Antar and J.Y. Siddiqui, “ An antenna advance for Cognitive Radio: Introducing Multilayered Split Ring Resonator Loaded Printed Ultra-Wideband Antenna with Multi-Functional Characteristics” IEEE Antennas and Propagation Magazine , Vol. 60, issue. 2, pp 20-33, March 2018.

[5] J. Y. Siddiqui, C. Saha, C. Sarkar, L. A. Shaik and Y. M. M. Antar, "Ultra-Wideband Antipodal Tapered Slot Antenna With Integrated Frequency-Notch Characteristics," IEEE Transactions on Antennas and Propagation, vol. 66, no. 3, pp. 1534-1539, March 2018

[6] C. Saha, J. Y. Siddiqui, A. P. Freundorfer, L.A. Shaik and Y.M.M. Antar, “Active Reconfigurable Ultra-Wideband Antenna with Complementary Frequency Notched and Narrowband Response” IEEE Access, Vol. 8, pp. 100802-100809, June 2020.