A FURTHER INVESTIGATION ON THE PERFOR- MANCE OF THE BROADSIDE COUPLED RECTANGU- LAR SPLIT RING RESONATORS

Abstract-In this paper, a numerical study based on the Finite Element Method (FEM) formulation of Ansoft's High Frequency Structure Simulator (HFSS) is reported to investigate the performance of a conformal Broadside Coupled Rectangular Split Ring Resonators (BC-SRR) of negative effective permeability around a resonant frequency of 1.27 GHz for non-linear polarization applications. The size of the BC-SRR is 15 mm × 15 mm × 0.8 mm on a polyimide substrate with a relative permittivity of 3.5 and a loss tangent of 0.004. The performance of the BC-SRR is characterized in terms of reflection and transmission spectra, effective relative permittivity and permeability, and the dispersion diagram for both flat and twisted profiles. The flat BC-SRR operates over the frequency range from 1.2615 to 1.2842 GHz. The twisted BC-SRR inclusions are investigated at 90 • . It has been found that the resonant frequency is changed to 1.1064 GHz and bandwidth becomes from 1.08 GHz to 1.0537 GHz for the twisted profile. Moreover, it is found that the unit cell of the twisted BC-SRR profile is based on two BC-SRRs inclusions. Furthermore, it is found that the twisted profile exhibits negative relative permittivity and permeability simultaneously

Design of a Planar Sensor Based on Split-Ring Resonators for Non-Invasive Permittivity Measurement

The permittivity of a material is an important parameter to characterize the degree of polarization of a material and identify components and impurities. This paper presents a non-invasive measurement technique to characterize materials in terms of their permittivity based on a modified metamaterial unit-cell sensor. The sensor consists of a complementary split-ring resonator (C-SRR), but its fringe electric field is contained with a conductive shield to intensify the normal component of the electric field. It is shown that by tightly electromagnetically coupling opposite sides of the unit-cell sensor to the input/output microstrip feedlines, two distinct resonant modes are excited. Perturbation of the fundamental mode is exploited here for determining the permittivity of materials. The sensitivity of the modified metamaterial unit-cell sensor is enhanced four-fold by using it to construct a tri-composite split-ring resonator (TC-SRR). The measured results confirm that the proposed technique provides an accurate and inexpensive solution to determine the permittivity of materials

A Printed Reconfigurable Monopole Antenna Based on a Novel Metamaterial Structures for 5G Applications

A novel antenna structure is constructed from cascading multi-stage metamaterial (MTM) unit cells-based printed monopole antenna for 5G mobile communication networks. The proposed antenna is constructed from a printed conductive trace that fetches four MTM unit cells through four T-Resonators (TR) structures. Such a combination is introduced to enhance the antenna gain-bandwidth products at sub-6GHz bands after exiting the antenna with a coplanar waveguide (CPW) feed. The antenna circuitry is fabricated by etching a copper layer that is mounted on Taconic RF-43 substrate. Therefore, the proposed antenna occupies an effective area of 51 × 24 mm2. The proposed antenna provides an acceptable matching impedance with S11 ≤ −10 dB at 3.7 GHz, 4.6 GHz, 5.2 GHz, and 5.9 GHz. The antenna radiation patterns are evaluated at the frequency bands of interest with a gain average of 9.1–11.6 dBi. Later, to control the antenna performance, four optical switches based on LDR resistors are applied to control the antenna gain at 5.85 GHz, which is found to vary from 2 dBi to 11.6 dBi after varying the value of the LDR resistance from 700 Ω to 0 Ω, in descending manner. It is found that the proposed antenna provides an acceptable bit error rate (BER) with varying the antenna gain in a very acceptable manner in comparison to the ideal performance. Finally, the proposed antenna is fabricated to be tested experimentally in in free space and in close to the human body for portable applications

Minkowski Based Microwave Resonator for Material Detection over Sub-6 GHz 5G Spectrum

This paper describes the performance of a low-cost, high-sensitive microwave resonator for 5G modern wireless communication systems operating through sub-6GHz spectrum. Here, the proposed resonator is constructed from a Minkowski fractal open stub that is coupled to an interdigital capacitor. It is fetched to a circular spiral inductor structure with a back loop to increase the resonator quality and it operates at a frequency resonance of 524 MHz. Since the purpose of the study is to apply such technology to characterize liquid properties, the presented resonator is mounted on an FR4 substrate with a thickness of 1.6 mm and an area of 40× 60 mm2, Using CST MWS commercial software, the resulting design dimensions are optimized. The proposed design performance which is demonstrated in terms of S21 magnitude is found to vary significantly by the variations in the photo-resistor. Such a property motivated the authors to consider it for material detection as the frequency stability with a photo-resistor value change is relative to the light incidence. In such a manner, the achieved results are found to behave linearly without discrepancy due to the effects of diffraction from the resonator layers. This technology is frequently used as a strong contender for a variety of contemporary wireless technologies that may invoke optical-based interface systems

Design of Compact Flexible UWB Antenna Using Different Substrate Materials for WBAN Applications

In this paper, the design process of compact flexible ultra-wideband (UWB) antenna using various substrate materials such as FR4, Kapton, and Rogers RT5880 is discussed and experimentally investigated. The proposed antenna is structured as a flexible model that can conform to suite the human body surface to be suitable for wireless body area network (WBAN) applications. The performance parameters of the antenna have been evaluated by using CST Microwave Studio software and very similar results have been achieved by applying FR4, Kapton, and Rogers RT5880 substrates, but the latter substrate provides optimized results. Therefore, the Rogers RT5880 substrate was chosen to realize the experimental antenna to validate its performance. There was excellent agreement between the simulated and measured results. The proposed antenna is miniature having dimensions of 22×28×1.6 mm3 and operates at dual band across 4.8-5.3 GHz and 7.0-8.6 GHz. It has a high gain above 5.5 dBi at both bands and radiates omnidirectionally. Moreover, it has a simple geometry making it easy to manufacture and is therefore cost effective. This antenna is applicable for wireless body area network (WBAN)