Compact Composite Right/left-handed Research Articles

Compact Dual-Band Metamaterial-Based High-Efficiency Rectenna: An Application for Ambient Electromagnetic Energy Harvesting

A compact composite right/left-handed (CRLH)-based dualband rectenna is proposed for electromagnetic (EM) energy harvesting at the operating frequencies of Wi-Fi (2.5 GHz) and Worldwide Interoperability for Microwave Access (WiMAX) (3.6 GHz) bands. The rectenna consists of a dual-band antenna and dual-band rectifier. The antenna is realized in a microstrip topology using a balanced CRLH transmission line (TL) with an open termination. It measures 0.36 # 0.2 # 0.00049 mo (mo is the free-space guided wavelength) at 2.5 GHz and operates at 2.5 and 3.6 GHz, with an operating bandwidth of 4.75 and 3.3%, respectively, and a peak gain of 2.6 decibels relative to isotropic (dBi) at 2.5 GHz and 1.6 dBi at 3.6 GHz. The dual-band rectifier is designed using a novel CRLH-based microstrip topology composed of microstrip lines and lumped components. The overall rectifier volume is 0.3 # 0.2 # 0.0005 mo at 2.5 GHz. The measured radio-frequency (RF)?dc conversion efficiency is more than 59% at 2.5 GHz and 41% at 3.6 GHz, for an input power of 2 dB milliwatts (dBm) in both cases.

Design of Compact Balanced-to-Balanced Diplexer Using Dual-Mode CRLH Resonator for RFID and 5G Applications

A compact balanced-to-balanced diplexer based on composite right/left-handed (CRLH) resonator is presented in this paper. The proposed compact CRLH resonator is used to design two balanced channels, which are connected by T-junction to construct the balanced-to-balanced diplexer. Under differential-mode (DM) operation, the proposed CRLH resonator can provide two adjacent DM resonant modes to produce one passband of the balanced-to-balanced diplexer. Under common-mode (CM) operation, the CRLH resonator also generate two CM resonant modes, whose locations are far away from DM resonant modes, resulting in a perfect CM suppression level. To verify the design methodology, a compact balanced-to-balanced diplexer operated at 2.45 GHz and 3.47 GHz is designed and fabricated for multi-service system integrated with microwave RFID and 5G applications. The proposed balanced-to-balanced diplexer shows high CM suppression level and channel-to-channel isolation performance. The measured results are agree well with the simulated ones.

A Wide-Angle Circularly Polarized Tapered-Slit-Patch Antenna With a Compact Rectifier for Energy-Harvesting Systems [Antenna Applications Corner

A tapered-slit-patch antenna with wide-angle circularly polarized (CP) radiation and a compact rectifier was investigated for energy-harvesting systems. A tapered-slit octagonal-shaped patch radiator was implemented to realize the CP microstrip antenna with wide-angle radiation using a proximity-coupled feed. Eight tapered slits with length difference of 1.3% were embedded along the octagonal directions symmetrically on the microstrip radiator from the patch's center. The antenna prototype showed a gain of more than 5.8 dBic across the CP bandwidth of 7 MHz (894-901 MHz) with a 3-dB axial ratio (AR) beamwidth of more than 180°. A compact composite right/left-handed (CRLH)-based rectifier operating at 900 MHz was designed to be used along with the antenna for radio-frequency (RF) energy-harvesting system. A microstrip line forms the righthanded part of the CRLH transmission line (TL), and the lumped components form the left-handed part of the CRLH TL. The proposed rectifier was compact with size of 0.18λ 0 × 0.075λ 0 × 0.0002λ 0 at 900 MHz with a high RF-dc conversion efficiency of 43%.

A dual-band efficient circularly polarized rectenna for RF energy harvesting systems

A multilayered circularly polarized (CP), dual-band, stacked slit-/slotted-patch antenna with compact size and with compact rectifier is offered for RF energy harvesting systems. The compact dual-band CP antenna size is able to achieve by stacking slotted-circular-patch (SCP) on the substrate above the tapered-slit-octagon patch (TSOP). Dual-band CP radiation is realized by stacking the SCP on the TSOP and the microstrip feedline with metallic-via to SCP. Eight-tapered-slit with length difference of 6.25% are embedded along the octagonal directions symmetrically on the TSOP from the patch's center and two unequal size circular slots are embedded in diagonal axis onto SCP to produce dual-orthogonal modes with almost equal magnitude for CP waves. The designed antenna is realized measured gain of greater than 5.2 dBic across the band (0.908-0.922 GHz) with maximum gain of 5.41 dBic at 0.918 GHz and gain of greater than 6.14 dBic across the band (2.35-2.50 GHz) with maximum gain of 7.94 dBic at 2.485 GHz. An overall antenna volume is 0.36λ o × 0.36λ o × 0.026λ o (λ o is free space wavelength at 0.9 GHz). A compact composite right-/left-handed (CRLH) based rectifier with dual-band at 0.9 and 2.45 GHz is designed, prototyped, and measured. The right-handed (RH) part of the CRLH transmission line (TL) is formed by a microstrip line. The left-handed (LH) part of the CRLH-TL is formed by lumped components. The measured RF-DC conversion efficiency is 43% at 0.9 GHz and 39% at 2.45 GHz with rectifier size of 0.18λ o × 0.075λ o × 0.0002λ o at 0.9 GHz.

A Compact CRLH Circularly Polarized Leaky-Wave Antenna Based on Substrate-Integrated Waveguide

A compact single-radiator circularly polarized (CP) leaky-wave antenna (LWA) based on composite right/left-handed (CRLH) transmission line is presented. The proposed antenna is based on substrate-integrated waveguide (SIW), and its unit cell consists of a T-shaped interdigital slot, which provides a CRLH property, a proper CP, and also effective compactness for the full-length LWA. The proposed LWA provides beam scanning from −19° to +84° over the frequency range of 7.35–10.15 GHz, while maintaining a good CP. By providing the balanced condition for the CRLH unit cell, a continuous backward-to-forward scanning including broadside is achieved. The maximum gain of the LWA is 8.95 dB which is satisfactory, considering the compactness of the antenna. Moreover, the radiation efficiency has an average of 85.7% over the operating frequency band. The measurement results are in good agreement with the simulation ones and show considerable advantages over the SIW-based CP LWAs proposed in the recent literature.

Compact Quarter-Wave Resonator and Its Applications to Miniaturized Diplexer and Triplexer

Novel and compact composite right/left-handed (CRLH) quarter-wave type resonators are proposed in this paper. The resonator can resonate at the frequency where the electrical length is phase-leading or negative, which results in a smaller size as compared to the conventional phase-delayed microstrip-line resonator. Furthermore, it is only half the size of the CRLH half-wave resonator resonating at the same frequency. In addition, the proposed resonator is capable of engineering the multiresonances very close to each other, which makes it suitable to implement the miniaturized multiband microwave components such as diplexers and triplexers. A very compact diplexer and a very compact triplexer are proposed based on the proposed CRLH quarter-wave resonators in this paper and both of them have demonstrated very good performance. Specifically, compared to the referenced works based on the conventional microstrip resonators, the proposed diplexer and triplexer are 50% and 76% smaller than their microstrip counterparts, respectively.

A Novel Compact MIM CRLH Transmission Line and Its Application to Leaky-Wave Antenna

A novel kind of compact composite right/left-handed (CRLH) transmission line (TL) is proposed in this paper. The unit cell of this structure consists of a novel metal-insulator-metal (MIM) parallel plates and a meander line shorted to the ground. The left-handed (LH) series capacitance per-unit-area of the novel MIM capacitor can be four times as much as that of the existing MIM, and this property shows high capability of compactness. As an application example of this novel design, a leaky-wave antenna (LWA) is presented, which has the capability of continuous frequency scanning. Full-wave method is employed to simulate the structure, and the equivalent-circuit model is applied to achieve basic insight into the behavior of the structure. The experimental results are presented for validation of the proposed structures. This novel kind of MIM exhibits great potential for the minimization of microwave devices and antennas constructed by the CRLH structures.