Mahmoud A. Abdalla

Compact and Closely Spaced Metamaterial MIMO Antenna With High Isolation for Wireless Applications

This letter presents a design of a two-element multiple-input-multiple-output (MIMO) metamaterial-based antenna. The two antenna elements operate at 5.8 GHz for wireless applications. The two antenna elements are designed employing only one left-handed unit cell. The reduction of mutual coupling between the two antenna elements is achieved by using a simple defected ground structure between them to limit the surface waves between them. The distance between the two antenna elements is only 1.8 mm (0.034 λ0). The designed antenna elements have better than -45 dB coupling isolation between the two inputs. Moreover, the proposed MIMO antenna has the advantage of compactness (its size is only 2.36 × 2.6 cm2). The design represents size reduction of more than 50% compared to conventional patch antennas operating at the same frequency. The proposed MIMO system has -55 dB correlation coefficient between its two elements.

On the study of left-handed coplanar waveguide coupler on ferrite \r\nsubstrate

This paper introduces a 3 dB tunable symmetric left handed coupled line coupler implemented on ferrite substrate. The proposed coupler is realized in LH coplanar waveguide configuration constructed using interdigital capacitors and meandered line inductors. The analytical analysis and the numerical verification of the proposed couple line coupler are presented. The full wave numerical simulation results for different DC magnetic bias indicate that a tunable left handed coupled line coupler propagation with transmission coefficient up to 3 dB and isolation level more than 25 dB over a wide bandwidth can be achieved.

Graphene Nanoflakes Printed Flexible Meandered-Line Dipole Antenna on Paper Substrate for Low-Cost RFID and Sensing Applications

In this letter, a graphene nanoflakes printed antenna is presented. Graphene nanoflakes conductive ink has been screenprinted on paper substrate and compressed to achieve the conductivity of 0.43 × 105 S/m. Low-profile meandered-line dipole antenna has been fabricated as a proof of concept due to its electrically small size and simple structure. The maximum gain is measured to be -4 dBi, the -10-dB bandwidth ranges from 984 to 1052 MHz (6.67%), and the radiation pattern is verified as being typical radiation patterns of a dipole-type antenna. The radiation efficiency is 32%. The measurement results reveal that graphene nanoflakes printed antenna can provide practically acceptable return loss, gain, bandwidth, and radiation patterns for midand short-range RFID, and sensing applications. Furthermore, screenprinting technique employed in this work is of extremely low cost and capable of producing antennas in mass production.

Design and Analysis of Tunable Left Handed Zeroth-Order Resonator on Ferrite Substrate

This paper presents, for the first time, a tunable left handed coplanar waveguide zeroth-order resonator on a ferrite substrate. Analysis and design procedures of the proposed resonator are introduced. The proposed resonator is designed to be tuned over the frequency band from 3 to 4.85 GHz with lower than 3-dB insertion loss and better than 10-dB return loss. The dimensions of the proposed resonator are 8.3 times 20 mm. The advantages of the proposed resonator are its tuning capability in addition to its compact size.

Multi-Band Functional Tunable LH Impedance Transformer

This paper presents, for the first time, the analysis and design performance of tunable left handed coplanar waveguide transformer designed on a ferrite substrate. The proposed transformer is studied analytically and verified numerically. Results show that the proposed transformer has tunable dual band of operation with frequency tuning range from 2.35 GHz to 3.85 GHz with return loss from 10 dB to 25 dB. Such tunability can be achieved by changing the DC magnetic bias. The advantages of the proposed transformer are its tuning capability, its multi functionality operation, and its compact size.

A dual mode CRLH TL metamaterial antenna

This paper presents a novel configuration for dual mode CRLH metamaterial antenna. The proposed configuration comprises two short and open circuits in CRLH unit cells. The proposed antenna configuration has the advantages of its independent dual band design capabilities the design can be extended to achieve a wide band antenna performance. Moreover, the structure is very compact in size. Different studied cases are introduced in this paper to confirm all these advantages. Only one coplanar waveguide CRLH cell was employed in the study which consists of a series interdigital capacitor and shunt strip inductor. A prototype band WiMAX antenna performance is examined experimentally. The results illustrates that the antenna has a dual band at 3.5 GHz and 5.2 GHz with return loss better than 10 dB. The antenna size is 26 × 23 mm2. The antenna CRLH radiating cells length is only 5 mm which is only 15 % and 33% compared to conventional antenna operates at the same frequency.

On the study of CWP dual band left handed propagation with reciprocal and nonreciprocal characteristics over ferrite substrates

This paper presents, for the first time, a new LH CPW TL, which exhibits dual-band LH passbands with reciprocity and non-reciprocity in addition to the conventional right handed (RH) passband. The proposed TL is composed of a CPW over a ferrite substrate, magnetized in a direction perpendicular to its strip, and periodically loaded with shunt planar strip inductors and series air gap capacitors. The negative permeability of the ferrite substrate allows it to play the role of an additional effective series capacitive loading. The first LH passband at lower frequencies is reciprocal and the second LH passband at moderate frequencies has non-reciprocity. The new TL is also tunable by changing the applied magnetic bias. In comparison with microstrip LH TL, a CPW LH TL requires lower dc magnetic bias since it has much smaller demagnetization factor.

A new compact microstrip triple band antenna using half mode CRLH transmission line

This paper presents a compact triple band metamaterial antenna for different wireless applications. The designed antenna is based on a new configuration as half mode metamaterial left handed transmission line. The proposed antenna was designed to cover the frequency bands from 2-2.4 GHz, 5.4-6 GHz, and 6.8-8 GHz. The theoretical design principles of half mode left handed transmission line antenna is explained. The antenna design has been validated using the electromagnetic full wave analysis. The antenna has the advantages of a compact size (only 2.5 × 2.5 cm2) which is only is less than 25% at lower frequency band compared to the size of the conventional patch antenna. The results confirm the antenna triple bands operation with return loss better than 15 dB at each operating band and better than 10 dB cross polarization isolation.

Compact half-wavelength metamaterial Stepped Impedance Resonator (SIR)

This paper presents a λg/2 microstrip Stepped Impedance Resonator (SIR) based on Composite Right/Left-Handed (CRLH) transmission line for the first time. The SIR resonates at 2.1 GHz for Wireless Local Area Network (WLAN) applications. Supported by theory and full-wave simulations, a comparison is made between this design and its conventional counterpart. The CRLH SIR design presented in this paper is not only 44.76% smaller in length than its conventional counterpart, but also benefits from a much better performance. by proper structure design and substrate selection, this technique is also applicable to very high frequencies.

EXPERIMENTAL VERIFICATION OF A TRIPLE BAND THIN RADAR ABSORBER METAMATERIAL FOR OBLIQUE INCIDENCE APPLICATIONS

This paper presents the theory, design, and experimental investigation of an ultra thin (6% ‚0) and triple band metamaterial radar absorber. The theoretical design of the reported absorber is investigated. The absorber performance was validated using the electromagnetic simulations and conflrmed by experimental measurements for difierent incidence angles. The results conflrm that the proposed metamaterial absorber can demonstrate triple bands with better than i15dB re∞ection coe-cient for all incident angles.