1. UKM Learning and Research Repository
2. PHD Thesis / Tesis PHD
3. Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

Title:	Analysis of microwave range metamaterial absorber for communication system
Authors:	Saif Hannan (P98220)
Supervisor:	Mohammad Tariqul Islam, Prof. Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Metamaterial absorber Microwave range Communication system
Issue Date:	28-Apr-2022
Description:	Metamaterial (MM) absorbers have become the essential part of electromagnetic (EM) communication systems due to many practical applications like radar cross-section reduction, enhancement of antenna gain and directivity, EM coupling reduction in radio frequency devices, sensing enhancement of EM sensors, EM energy harvesting, specific absorption rate reduction, etc. Along with the absorption of EM waves, the negative value of permittivity or permeability can lead to unnatural EM properties named MM characteristics. These MM properties ensure the law of energy conservation as per the Poynting theorem and thus can be applied for practical applications. Many MM absorbers are proposed, but the problem is none have shown any relation or formula connecting the MM properties with the design parameters. There are no explanations for being an MM absorber co-polarization insensitive or perfect absorber. Moreover, there are no frequency-targeted MM absorbers found for microwave applications in recent literature. The objective of this research was to discover these unknown factors, and thus six MM absorbers have been designed and analyzed. A frequency-targeted copolarization insensitive MM absorber for 2.4 GHz and 5 GHz dual-band WiFi applications was developed to relate the structural parameters with resonance frequencies. On the other hand, the perfect MM absorbers were designed with a 90- degree rotational symmetric resonator structure for C, X, and Ku bands that can absorb both co- and cross-polarized EM waves effectively at several resonance frequencies. Both types were designed without any lumped element in the resonator patch. The dualband WiFi absorber was designed using two compact and co-centred split-ring resonators (SRR) with an effective medium ratio of 12.49 that showed insensitivity up to 180-degree incident angle with a negative permittivity value and maximum absorptions at the resonance frequencies. The structural parameters were formulated to connect the SRR dimensions with the resonance frequencies and with a novel idea, the "filling factor". The effective absorptions by perfect absorber were found from 4.1021 GHz to 4.2686 GHz, 5.22 GHz to 5.3058 GHz, 8.6133 GHz to 8.7548 GHz, 9.2568 GHz to 9.3807 GHz, and 10.11 GHz to 10.254 GHz considering at least -10 dB value of both S11 and S21 parameters, corresponding to at least 90% absorption and a total of 0.6617 GHz perfect absorption. In addition, a near-zero refractive index of 14 GHz bandwidth was achieved for one of the perfect absorbers for the whole operating frequency. The EM behaviour of the absorbers was validated by proper equivalent circuits and finally measured by a vector network analyzer to justify the performances. These analyses have made it possible to design any frequency-targeted and perfect MM absorbers and propose practical EM applications for next-generation microwave devices.,Ph.D.
Pages:	160
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.