Composite Right/left-handed Research Articles

Multiband planar antenna with CSRR loaded ground plane for WLAN and fixed satellite service applications

Abstract In this paper, a novel approach to achieve multiband antenna operation using metamaterial based resonant structures is presented. Multiband antenna operation is achieved by employment of complementary split ring resonators (CSRR) printed in the ground plane. The CSRRs resonate at different frequencies according to their optimized dimensions. Proposed approach features simple design and fabrication possibility compared to other methods of achieving multiband antenna operation such as usage of composite right/left-handed (CRLH) transmission line or split ring resonators (SRR) or CSRR around the patch surface. The proposed method is demonstrated through simulation and experimental measurements using three CSRRs with different resonant frequencies together with a tuning CSRR and a radiating patch. Contribution of different CSRRs to obtain multiple resonances have been shown by surface current plots. Measured antenna gain of 2.78, 1.27 and 3.45 dB has been obtained at frequencies of 5.25, 6.28 and 7.29 GHz respectively. The measurements done on developed antenna exhibits close agreement with the simulation results. In context with the current communication application trends involving multiple operating bands like 5G, this approach may have immense application potential since the same can be adopted to achieve compact multiband antennae operation in other frequency bands of interest.

Compact Yagi‐Uda slot antenna with metamaterial element for wide bandwidth wireless application

In this article, an antenna with the combination of the microstrip slot and Yagi antenna is presented for wideband WLAN (wireless local area network) using CRLH (composite right/left-handed) as a metamaterial (Left-hand) element. The T-shape feed line is investigated as a radiator section and modified for enhancing the bandwidth. The periodic elements are utilized as a novel type of the director to improve the bandwidth to more than 35% and increase the gain of the antenna to more than 80% where the three CRLH elements array are employed as the director of the Yagi antenna. The proposed antenna covers the 2.2 to 8 GHz (113% bandwidth) with a return loss of less than −6 dB (VSWR less than 3), which makes it suitable for wireless applications for covering different bands including WLAN, LTE (Long Term Evolution), and WiMAX with 47% miniaturization. The final antenna is simulated with CST microwave studio by the time-domain method of FIT (Finite integration technique). The total size of the antenna is 60 mm × 40 mm × 1.6 mm, which is printed on an FR-4 substrate, and the experimental results confirm the simulations.

Unbalanced CRLH behavior of ferrite-loaded waveguide operated below cutoff frequency

ABSTRACT This paper proposes a new unbalance composite right/left handed (CRLH) transmission line that consists of a normally magnetized ferrite-loaded rectangular waveguide. The left-handed (LH) behavior of this structure is based on the negative effective permeability of the ferrite material and the negative effective permittivity of the hollow metallic waveguide at the frequencies below the cutoff. By increasing the frequency and passing through the cutoff frequency, this structure behaves as a right handed (RH) transmission line. As a main advantage of the proposed structure, the CRLH response of this transmission line can be tuned by changing the magnetic bias of the ferrite layer. This tunable CRLH transmission line can be used to design a tunable microwave filter or a tunable leaky wave antenna (LWA) with backfire-to-endfire scanning capability. Compare to previous CRLH metamaterial structures, the proposed structure has an easy design and a wide frequency range of tunability.

60 GHz Compact Larger Beam Scanning Range PCB Leaky-Wave Antenna Using HMSIW for Millimeter-Wave Applications

A half-mode substrate integrated waveguide (HMSIW), based on printed circuit board (PCB) technology, is employed to construct a novel V-band leaky-wave antenna incorporating composite right-/left-handed (CRLH) media. Including modified half-sinusoidally varied interdigital capacitive slots on the radiating edge of the HMSIW enables the feature of effective CRLH media to produce adequate radiation coverage and bandwidth with improved sidelobe level (SLL) and higher gain. Unit cell characteristics and space harmonic analysis were thoroughly investigated through dispersion and Bloch impedance analysis. By appropriately tuning the physical parameters of the design, the balanced condition was obtained at a broadside frequency of 60 GHz. The highly directed radiated fan beam covered a scanning range of 120° with beam steering from -72° to 48° of the visible space. The proposed antenna operated over 55-65 GHz with a maximum realized gain of 14.5 dBi, maximum beamwidth of 9.15°, better than 15 dB SLL and 20 dB cross-polar radiation. All simulated responses showed reasonably good accordance with experimental data thereby validating the novel design of the proposed leaky-wave structure for millimeter-wave wireless applications.

Composite right/left‐handed ultra‐wideband metamaterial antenna with improved gain

AbstractA coplanar waveguide‐fed ultra‐wideband (UWB) composite right/left‐handed (CRLH) antenna is presented. It is designed by embedding CRLH unit‐cell on the top side and split‐ring resonator (SRR) on the bottom side of FR4 epoxy substrate. The UWB response is obtained by merging the resonances of CRLH unit‐cell and SRR with two additional resonances due to patch feed‐line and ground plane, respectively. Subsequently, the gain of UWB CRLH antenna is enhanced by loading two partial reactive impedance surfaces (PRISs) on the double layer FR4 substrate. First PRIS is embedded directly on the rear side of CRLH antenna (upper layer substrate) whereas the second PRIS is designed on the backside of the lower layer substrate. A considerable improvement in gain is observed over the frequency range from 6.2 to 10.6 GHz with peak enhancement of 1.75 dB. The proposed antenna is fabricated and measured. The measured results indicate −10 dB fractional bandwidth of 126.15% (3‐13.25 GHz) with realized gains of 2.2, 5.25, 5.5, and 7.3 dBi at 3.57, 7.46, 8.92, and 10.59 GHz, respectively. The simulated radiation efficiency is above 61% with a peak value of 86.21%. All measured and simulated results match reasonably well.

A Compact Highly Efficient Π-Section CRLH Antenna Loaded With Textile AMC for Wireless Body Area Network Applications

An ultrathin, compact, and highly efficient antenna based on the π-section composite right/left-handed (CRLH) methodology is presented. It operates at 2.45 GHz of the Industrial, Scientific and Medical (ISM) band with a physical size of 25 mm × 25 mm, a realized gain of 2.34 dBi, and a total efficiency of 87% in free space. Nevertheless, to maintain resonance at 2.45 GHz with body-loading scenarios, a high separation was required, leading to an overall large size. To circumvent that, an all-textile 2 × 2 artificial magnetic conductor (AMC) array was placed in-between the antenna and the human body. In free space, the low-profile integrated design exhibited a gain of 7.63 dBi (enhancement of 5.29 dBi) and total efficiency of 96.4%. The integrated design achieved a gain and total efficiency enhancements by 14.88 dBi and 72.4%, respectively, as well as, lower specific absorption rate (SAR) levels, in comparison with the CRLH antenna alone, for human loading cases. Results are achieved through circuit model and full-wave electromagnetic simulations. In addition, the CRLH antenna and AMC array structure were fabricated and measurements were undertaken, which agreed well with the simulated ones. Therefore, the integrated design is highly suggested to be recognized in wireless body area network (WBAN) and medical applications.

Analysis and Design Guidelines for Wideband CRLH SRR-loaded Coplanar Waveguide

This article presents a novel lumped-element equivalent circuit model for split-ring resonator (SRR)-based composite right/left-handed (CRLH) coplanar waveguide (CPW). The proposed model has closed-form expressions in terms of the parameters of the constituent transmission lines and is valid over a wide frequency range. This article also presents a novel slotline to coupled microstrip (MS) line $E$ -plane T-junction. Based on the circuit model and the proposed junction, systematic design procedures for ultrawideband balanced SRR-based CRLH CPW unit cells that benefit from the geometry of the unit cell and do not rely on adding extra components or parametric iterations are developed. This article also explains the layout constraints and presents alternatives to realize wideband designs. Two CPW unit cells using SRR and edge-coupled (EC) SRRs are designed, fabricated, and characterized. Simulations, which are in good agreement with measurements, show that the operating bandwidth can reach 97% and 78.21% for the two cells, respectively.

Wide-Angle Frequency-Scanning Array Antenna Using Dual-Layer Finger Connected Interdigital Capacitor Based CRLH Unit Cell

In this paper, a wide-angle frequency-scanning array antenna is presented for three-dimensional (3D) radar. Initially, a modified composite right/left-handed (CRLH) unit cell based on a dual-layer finger-connected interdigital capacitor (FCIDC) is analyzed. Compared with its conventional counterpart, the proposed unit cell eliminates the undesired high-order resonances and has a lower right/left-handed passband. Then, a broadband frequency-scanning feeding network, which has a large scanning angle, is designed using the proposed CRLH unit cell. The responses of the four output ports indicate that the network can offer desired amplitude and phase difference to scan towards both negative and positive elevation angles. To validate its performance, a tightly coupled planar quasi-Yagi antenna array is fed to synthesize an array antenna. The measured results show that the designed array antenna has an impedance bandwidth ($\vert \text{S}_{11}\vert <; -10$ dB) of 118.7% (2.55-10 GHz) and gains larger than 5dBi in the bulk of the band. Besides, the radiated beam can scan from -47° to 46° continuously when the frequency ranges from 3GHz to 9GHz.

A compact circularly polarized antenna using CRLH inspired transmission line and coupled ring resonator

This paper discusses the miniaturization process and bandwidth enhancement of circularly polarized (CP) antenna using asymmetric coplanar strip (ACS) feeding. The antenna mainly uses an ACS feeding scheme on which a via-less composite right/left-handed (CRLH) transmission line (TL) inspired unit cell is implemented for antenna miniaturization and a rectangular shaped annular ring slot is introduced in the asymmetric ground plane (AGP) for generating extended CP radiation. Due to this, the intended antenna offers a compact electrical size of 0.22 λ0 × 0.35 λ0 × 0.028 λ0 at 5.5 GHz and a smaller physical dimension of 12 mm × 19.5 mm × 1.52 mm with ka = 1.32. The novelty of the antenna is to generate an improved impedance bandwidth (IBW) of (5.33–5.86 GHz) 9.90%, and enhanced axial ratio bandwidth (ARBW) of (5.33–5.79 GHz) 8.27% with less design complexity. The intended CP antenna provides a measured gain of 2.43 dBic at 5.53 GHz and radiation efficiency better than 87% is obtained by maintaining the antenna compactness without the use of complicated vias. Also, the intended antenna provides a good AR beamwidth of 80° (+40° to -40°) and positive gain values for theta = ±36° and for all phi values (phi = 00–360°) at 5.55 GHz. Moreover, the intended antenna provides 42.85% miniaturization compared to a conventional monopole antenna. Hence, the intended antenna is well suited for the 5.80 GHz WLAN (5.725–5.875 GHz), and 5.5 GHz WiMAX (5.25–5.85 GHz) applications.

A novel compact folded zeroth-order resonant antenna for Internet of Things USB dongle applications

ABSTRACT This article presents a novel compact folded Zeroth-Order Resonant (ZOR) antenna using concept of Composite Right/Left-Handed (CRLH) transmission line operating in the WLAN/ISM bands of 2.4 and 5.2 GHz for Internet of Things (IoT) applications including USB dongle and radio-frequency identification (RFID) systems. It consists of two-unit cells of a CRLH transmission line and operates in a series resonant mode with an overall size of 1.6 mm × 38 mm × 9 mm. The measured results show that fractional bandwidths of 11.34% and 3.9% for S11 < −10 dB, and radiation efficiencies of 64.89% at 2.4 GHz and 78.88% at 5.2 GHz are obtained. A comparison between our proposed work and other existing works shows the achievement of considerable antenna miniaturization using the technique of CLRH transmission line. The measured and simulated results are generally in good consensus. Being novel and compact, the proposed design is a potential candidate for diverse IoT devices including USB dongles and low-profile RFID tags.

Graphene-Based Composite Right/Left-Handed Leaky-Wave Antenna at Terahertz

In this paper, a simple terahertz (THz) leaky-wave antenna (LWA) composed of periodic gapped graphene ribbons and a silicon substrate is presented. The graphene sheets of the antenna operate in an electric field with a resonance distribution of transverse electric (TE) surface plasmon polaritons (SPPs). The THz LWA has both negative and positive propagation constant with the variation of frequencies. Thus, the LWA performs as a composite right/left-handed (CRLH) LWA with backfire-to-endfire beam steering capability in the THz band. The working principle of the THz LWA is analyzed in detail using the theory of dispersion relation formulae and the equivalent CRLH circuit model. The THz LWA is verified by numerical simulations, and the frequency scannable capability of the THz LWA is confirmed. The proposed antenna has great potential applications for the THz LWA of the radiation capability in the entire upper quadrants.

A broadband and excellent flatness power amplifier with novel‐designed band‐pass filter based on composite right/left‐handed unit cell

AbstractIn this paper, a broadband and excellent flatness power amplifier (PA) with a novel‐designed band‐pass filter based on composite right/left‐handed (CRLH) unit cell structure is proposed. On studying the structure of CRLH unit cell, a way to enhance PA bandwidth, gain flatness, and power‐added efficiency (PAE) flatness is explored. The novel‐designed CRLH unit cell structure is studied and applied in PA design. The measurements show that the PA has an output power of greater than 40 dBm, a gain flatness of 0.5 dB, and a PAE flatness of 4.4% within 1.7‐3.1 GHz bandwidth.

Compact Metamaterial Based $4\times4$ Butler Matrix With Improved Bandwidth for 5G Applications

This paper proposes a novel compact 4 × 4 butler matrix (BM) with improved bandwidth based on open-circuit coupled-lines and interdigital capacitor unit-cell to develop composite right/left handed (CRLH) transmission-line (TL) metamaterial structure. The BM is implemented by the combination of compact 3dB quadrature hybrid couplers, 0dB crossover and 45° phase shifter on a single FR4 substrate (er = 4.3 and h = 1.66 mm). The simulated and measured result shows that the return loss and isolation loss are better than 14 dB at all the ports, good insertion loss of -7 ± 2dB, which cover the frequency range of 3.2 GHz to 3.75 GHz. The phase difference of -45°, 135°, -135° and +45° are achieved with a maximum average phase tolerance of 5°. The overall dimension of the BM is 70mm × 73.7mm, which shows the compactness of the proposed design that is 75% size reduction and 8.2 times improvement in the bandwidth (550MHz) as compared to conventional BM. The CST microwave studio is used to design and perform the simulations. Additionally, the simulated and measured scattering parameters and phase differences show that they are in good agreement. This compact and improved bandwidth of the proposed BM is suitable for 5G antenna array beamforming network.

A Dual-Band Omnidirectional Circular Polarized Antenna Using Composite Right/Left-Handed Transmission Line With Rectangular Slits for Unmanned Aerial Vehicle Applications

A dual-band omnidirectional circularly polarized (CP) antenna using composite right/left-handed (CRLH) transmission line (TL) with miniaturized size is presented. The antenna consists of a circular radiation patch and a circular ground connected by three copper shorting vias, on which three rectangular slits are etched. Two sets of opposite branches are arranged in sequence around the radiation patch and ground to widen the impedance bandwidth (BW). The zeroth-order resonance (ZOR) structure by CRLH-TL and meandering technology allow miniaturization of the antenna, and rectangular slits realize wide low axial-ratio (AR) performance in the azimuth plane. The dual-band antenna is fabricated and measured. The overall size of the antenna prototype is only 0.208λ L × 0.208λ L × 0.026λ L , where λ L is the free-space wavelength at the center working frequency of the low band. The BW in the lower band has a range of 2.39 GHz to 2.42 GHz, equivalent to 1.25%, and that of the upper band has a range of 5.6 GHz to 6.0 GHz, equivalent to 6.90%. The AR bandwidth (ARBW) has ranges of 1.9 GHz to 2.6 GHz at 2.4 GHz, approximately 29.2%, and 4.6 GHz to 7.3 GHz at 5.8 GHz, equivalent to 46.6%. The overlap BW covers the two frequencies of unmanned aerial vehicle (UAV) image transmission, 2.4 GHz and 5.8 GHz in China.

A 67-86 GHz Spectrum-Efficient CMOS Transmitter Supporting 1024-QAM With a Process-Variation-Tolerant Design

This paper describes a direct-conversion E-band transmitter (TX) in 65-nm CMOS. To demonstrate the feasibility of E-band 1024-quadrature amplitude modulation (QAM), a 67 to 86 GHz direct-conversion CMOS transmitter with broadband image rejection is presented. The transmitter contains an I (in-phase) and Q (quadrature-phase) modulator and a five-stage power amplifier. To achieve a 40 dBc image-rejection ratio (IRR) of the I/Q modulator for E-band, a broadband half-quadrature generator (HQG), which contains a composite right/left-handed (CRLH) based divider, quadrature couplers, and baluns is proposed. For the purpose of minimizing the phase imbalance, phase balance lines are utilized in HQG to achieve a 1-degree phase accuracy under different tuning lines. Subsequently, the reflection can be mitigated by optimizing the impedance matching between the HQG and the mixer core. Meanwhile, because millimeter-wave (MMW) circuits are susceptible to process variations, a process-variation-tolerant design is introduced to mitigate IRR variation, especially under 40 dBc. The transmitter demonstrates a measured flat conversion gain (CG) of 23±2 dB from 56 to 86 GHz. The proposed TX achieves an IRR better than 40 dBc from 67 to 86 GHz (bandwidth of 19 GHz) with a peak IRR of 56.2 dBc at 70 GHz. Furthermore, the proposed TX has exhibited a 6 bit/s/Hz spectral efficiency with 1024-QAM under the orthogonal frequency-division multiplexing (OFDM) modulation format. The 1.129 mm 2 ~E-band TX achieves a measured output power of 6.5 dBm with a total dc power consumption of 164 mW from a 1.2 V supply voltage.

Low-Profile Frequency-Reconfigurable LTE-CRLH Antenna for Smartphones

This paper presents a monopole antenna loaded with one frequency-reconfigurable composite right/left-handed (CRLH) unit cell. This antenna is designed by means of two varactor diodes and with changing capacitance operating at LTE700 (698-798 MHz), LTE850 (824-894 MHz), LTE900 (880-960 MHz), LTE1700 (1710-2155 MHz), LTE1800 (1710-1880 MHz), LTE1900 (1850-1990 MHz), LTE2100 (1920-2170 MHz), LTE2300 (2305-2360 MHz), LTE2500 (2496-2690 MHz), LTE2600 (2500-2690 MHz), and GPS (1176 MHz, 1227 MHz) frequencies that cover most of the LTE bands for smartphone handsets, which is a combination of two distributed and compact modes, in which the varactor diodes, as compact elements, play a significant role in reducing the antenna dimensions. By changing the capacitance, the entire frequency band of 700 MHz and 900 MHz was achieved. The CRLH structure, in turn, reduces the dimensions of the antenna and generates resonant frequencies less than the resonance frequency of the monopole. At these frequencies, the radiation patterns are quasi-omnidirectional.

Electrically small circularly polarized antenna using vialess CRLH‐TL and fractals for L‐band mobile satellite applications

AbstractThis paper explains the design and development of an electrically small (ka = 0.59) circularly polarized (CP) antenna based on vialess composite right/left‐handed (CRLH) transmission line (TL) and third‐iterative fractals (TIF) applicable for 1.637 GHz L‐band mobile satellite applications. The idea behind the CP antenna originates from the combination of curved meander line inductor on the top side of the substrate back coupled with TIF in backside of the substrate. The loading of TIF provides an increased level of cross polarization by adjusting the dimensions of TIF which is almost equal to the main polarization level of original CRLH‐TL loaded antenna on the top side of the substrate. Due to this, the antenna can generate two orthogonally polarized modes for supporting CP radiation with excellent miniaturization and improved gain. The overall dimensions of the proposed antenna are 22 × 27 × 1.27 mm with radiating element size including the ground plane are 0.11λ0 × 0.14λ0 × 0.006λ0 at 1.635 GHz. The proposed antenna can provide excellent miniaturization of 68.51% compared with the conventional monopole antenna with improved radiation performance. The antenna provides an acceptable impedance bandwidth of 0.73%, improved gain of 1.79 dBi without using complex vias, excellent miniaturization, and low profile (0.006 λ0) compared to existing similar type of antennas in the literature.

A Compact 3.3–3.5 GHz Filter Based on Modified Composite Right-/Left-Handed Resonator Units

In the RF (Radio Frequency) front-end of a communication system, bandpass filters (BPFs) are used to send passband signals and reject stopband signals. Substrate-integrated waveguides (SIW) are widely used in RF filter designs due to their low loss and low cost and the flexibility of their integration properties. However, SIW filters under 6 GHz are still too large to meet the requirement of portable communication devices due to their long wavelength. In this paper, a very compact fully integrated SIW filter is proposed and designed with RT6010 dielectric material to meet the small size requirement of portable devices for next-generation sub-6 G applications. The proposed filter contains two sawtooth-shaped composite right-/left-handed (CRLH) resonator units, instead of traditional rectangular-shaped CRLH resonator units, which makes the filter more compact and cost effective. The filter is designed and fabricated on an RT6010 substrate, with a size of only 10 mm × 7.4 mm. The measurement results illustrated that the proposed BPF shows a passband covering the frequency range of 3.25–3.45 GHz; the minimum passband insertion loss is only 2.4 dB; the stopband rejection is better than −20 dB throughout the frequencies below 3.0 GHz and above 3.8 GHz; S11 is as low as −37 dB at 3.35 GHz; and the group delay variation is only 1.4 ns throughout the operation bandwidth.

Continuous Beam Scanning at a Fixed Frequency With a Composite Right-/Left-Handed Leaky-Wave Antenna Operating Over a Wide Frequency Band

Fixed-frequency beam scanning leaky-wave antennas (LWAs) that can scan their main beam over a specific frequency band are highly desired for future wireless communication systems. A composite right-/left-handed (CRLH) LWA is developed in this article that facilitates fixed-frequency continuous beam scanning over a wide operational frequency band. A variation of a simple single-layer nonreconfigurable frequency-based continuous beam scanning CRLH LWA is considered first. Its dispersion properties are approximately investigated using an equivalent circuit model. It is reported how two groups of varactor diodes can be incorporated into its basic circuit model to electronically control its dispersion behavior. An optimized reconfigurable CRLH LWA with practical dc biasing lines is then realized from this nonreconfigurable design. Fixed-frequency continuous beam scanning, from backward to forward directions through broadside, is reported over a wide operational frequency band. Simulations predict that the antenna can operate from 4.75 to 5.25 GHz with the main beam being continuously scannable at each frequency point. A prototype was fabricated, assembled, and tested. The measured results confirm its simulated performance characteristics.

Compact Co-design of Conformal 4G LTE and mmWave 5G Antennas for Mobile Terminals

An integrated design of conformal 4G and 5G Multiple-Input Multiple-Output (MIMO) antenna system is proposed. The 4G MIMO antenna system consists of electrically small two-element Composite Right/Left Handed (CRLH)-based Coplanar waveguide (CPW)-fed monopole antennas, which cater to the class 7 4G Long-Term evolution (LTE) band. For mmWave 5G MIMO antenna system, two-element high gain microstrip patch antennas are proposed. The conformal CPW-fed CRLH Metamaterial (MTM)-based 4G LTE antenna is electrically small with dimensions 20 × 20 × 0.254 mm3. The proposed antenna system has a forward gain of 2.15 dBi. Also, a conformal microstrip-fed patch antenna with an orthogonal pattern diversity at 28 GHz with a forward gain of 9 dBi is presented. Both the proposed antennas are integrated electrically close by 0.004 λ for minimal physical footprint post-integration in a typical smartphone case. The isolation is less than 35 dB. Real-world deployment studies have been presented.