Zeroth-order Resonance Mode Research Articles

Hybrid Metamaterial-TL-Based, Low-Profile, Dual-Polarized Omnidirectional Antenna for 5G Indoor Application

A novel hybrid metamaterial-transmission line (TL)-based dual-polarized omnidirectional antenna with a low profile and high port isolation for 5G indoor applications is proposed. A compact shared aperture hybrid metamaterial-TL structure is first proposed, which is carefully analyzed by dispersion curves and current distribution. The hybrid metamaterial-TL structure consists of a mushroom-like composite right/left-handed TL (CRLH-TL) and a ring-shaped mu-negative TL (MNG-TL), forming a pair of orthogonal zeroth-order resonant (ZOR) modes. The shunt ZOR mode of the CRLH-TL structure is successfully excited, which radiates vertically polarized (VP) waves. Horizontal polarization (HP) is realized by exciting a series ZOR response from the ring-shared MNG-TL. By simultaneously exciting two orthogonal ZOR modes, a dual-polarized (VP and HP) omnidirectional antenna with high isolation and good roundness is designed and fabricated. With a low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.06\lambda _{0}$ </tex-math></inline-formula> , this dual-polarized antenna shows a measured overlapped −10 dB bandwidth of 14.1% (3.3–3.8 GHz), a port isolation larger than 39 dB, radiation efficiency higher than 80%, and cross pol. levels lower than −18 dB. It demonstrates the advantages of low profile, compact size, high isolation, good bandwidth, and radiation performance, and simple design for 5G indoor microcell, router, multi-input–multi-output (MIMO), or in-band full duplexing applications.

Compact radiator antenna: A new approach to enhance the bandwidth using ENG-TL and C-CSRR mushroom meta-resonator

This work presents a new and efficient approach for enhancing the bandwidth and reducing the E-plane cross-polarization (X-pol) of an epsilon negative transmission line (ENG-TL) antenna with reduced size for working in 2.4 GHz Industrial, Scientific and Medical (ISM) band. The antenna consists of ENG-TL on which a curved meander line inductor is loaded for the generation of zeroth-order resonance mode. Subsequently, a miniaturized and low profile (0.06 λ0 × 0.06 λ0 × 0.013 λ0 at 2.44 GHz) circular-complementary split-ring resonator (C-CSRR) based mushroom meta-resonator is stacked over the ENG-TL antenna enhances the bandwidth twice without increasing any additional area. The proposed antenna provides a radiating element size of 0.17λ0 × 0.15λ0 excluding the feedline and total antenna dimension including ground plane is 0.17λ0 × 0.20λ0 × 0.025λ0 at 2.45 GHz. The measured results shows an enhanced impedance bandwidth (IBW) of 7.40%, an acceptable gain of 2.8 dBi, and X-pol value better than 35 dB is obtained for the E-plane. The antenna compactness, extended IBW, low X-pol levels, improved gain, high gain-to-area ratio, and acceptable radiation efficiency indicates that the proposed antenna is appropriate for working in 2.4 GHz (2.4–2.484 GHz) ISM band.

A Triband Patch Antenna with Monopole-like and Patch-like Radiation Patterns for Multifunctional Wireless Systems

A triband patch antenna with monopole-like and patch-like radiation patterns for multifunctional wireless systems is proposed. The antenna consists of a single square radiation patch with an annular slot, a ground plane, and a top-loaded metal sheet. The top-loaded metal sheet is shorted to the ground plane for producing a zeroth-order resonant (ZOR) mode, which has an omnidirectional radiation pattern at the lowest operation band, and its performance is robust to the location of the probe feed. With the annular slot and the off-center probe feed, a dual-resonant TM01 mode is excited, yielding unidirectional radiation patterns for the two upper operation bands. The ZOR and the dual-resonant TM01 modes can be independently controlled, and a triband antenna prototype with a square patch of 24 mm is fabricated and tested. The first bandwidth is 2.5–2.7 GHz with omnidirectional radiation pattern, the second and the third bandwidths with unidirectional radiation are 3.3–3.9 GHz and 4.8–6.1 GHz, and the realized gains over the three bands are about 2.6, 6.5, and 7.5 dBi, respectively.

2-D Wide-Angle Scanning Phased Array With Hybrid Patch Mode Technique

In this letter, a microstrip patch hybrid mode technique is introduced to design a 2-D wide-angle scanning planar phased array. The proposed element consists of a circular patch and four rectangular parasitic patches distributed around the circular patch. In order to obtain wider radiation beamwidth (BW) in two orthogonal azimuth planes, the TM11 mode of the circular patch and the zeroth-order resonant mode of the parasitic rectangular patches are separately excited. Experimental results show that the proposed element can obtain 3 dB BW more than 156° in the two orthogonal azimuth planes. Moreover, an 8 × 8 planar phased array formed by this element can realize wide-angle scanning in a range of about ±65° in the two orthogonal azimuth planes. In the above scanning range, the sidelobe levels of the phased array are always less than −7.8 dB, the scanning gain fluctuation is less than ±1.73 dB, and the main polarizations on the two orthogonal planes are both θ -polarized. In addition, the phased array has a simple structure, a low profile, and convenient fabrication.

Compact Wideband Dual-Frequency Antenna Based on a Simplified Composite Right/Left-Handed Transmission Line with Hilbert Curve Loading

This paper addresses the issues of low bandwidth, gain, and efficiency of miniaturized microwave antennas by proposing a novel wideband dual-frequency coplanar waveguide antenna design based on a simplified composite right/left-handed (SCRLH) transmission line structure with Hilbert curve loading. The multifrequency characteristics of the SCRLH transmission line structure are evaluated theoretically, and the antenna parameters promoting bandwidth broadening under zeroth-order resonance (ZOR) and first-order resonance (FOR) mode operation are evaluated. The bandwidth broadening in the ZOR and FOR modes is accordingly revealed to be independent of the antenna length, and the structure therefore facilitates wideband operation under miniaturization. Finally, the dual-frequency ZOR and FOR mode antenna design with center frequencies of f0 = 1.865 GHz and f1 = 2.835 GHz is validated via simulation, and the performance of a compact prototype antenna is evaluated experimentally. The −10 dB return loss bandwidths at f0 and f1 are 187 MHz (from 1.773 GHz to 1.96 GHz) and 368 MHz (from 3.002 GHz to 3.37 GHz), and the corresponding relative bandwidths are 10.1% and 11.5%, respectively. The experimentally measured peak gains and radiation efficiencies at f0 are 1.54 dB and 81.3%, respectively, and those at f1 are 1.71 dB and 74.2%, respectively.

Experimental verification of zeroth-order resonance phenomenon in an acoustic composite right/left-handed metamaterial resonator

This study experimentally verified our previously proposed theory that describes the zeroth-order resonance phenomenon in a resonator made of acoustic composite right/left-handed (CRLH) metamaterials [J. Acoust. Soc. Am. 142, 2298 (2017)]. It was experimentally demonstrated that the zeroth-order resonance mode with a flat shape exists in the acoustic CRLH metamaterial resonator. It was also verified that the resonance frequency of zeroth-order resonance changes depending on the boundary condition at both ends of the resonator and essentially does not depend on the number of resonator units, consistent with the theory.

A Metamaterial Inspired ZOR Antenna Using IDC and Spiral Inductor with Partial Ground Plane for WLAN Application

In this article, an open-ended metamaterial antenna structure is designed for WLAN application. The antenna comprises of an interdigital capacitor (IDC) and spiral inductor with a partial ground plane. The IDC (shunt element) act as a varying parameter to control the zeroth-order resonance (ZOR) frequency, whereas spiral inductor (series element) is used to form a first negative order resonance frequency at 2.29 GHz. The ZOR mode has been excited at 4.53 GHz by employing complimentary right/left handed transmission line model in the structure and the first positive order resonance (FPOR) frequency is obtained at 4.9 GHz. A rectangular shaped stub has been used to act as a virtual ground for IDC. The proposed antenna design has total foot-print size of 0.29λ0 × 0.27λ0 × 0.024λ0. The fractional bandwidth of 20.41% (4.36–5.35 GHz) is achieved due to the merging of ZOR and FPOR mode respectively. In addition, it also exhibits a measured peak gain of 2.12 dB and 2 dB with a radiation efficiency of 77.76% and 87.62% at ZOR and FPOR frequencies respectively. A prototype of the proposed antenna structure has been fabricated and simulation results are experimentally rectified. A good agreement between simulation and measured results are obtained.

A Low-Profile Antenna With Omnidirectional and Unidirectional Radiation Patterns Over Two Operation Bands

A compact low-profile dual-band antenna with a single circular radiation patch is presented. The circular radiation patch is top-loaded by a metal strip, leading to a zeroth-order resonant (ZOR) mode with monopole-like radiation pattern at the lower operation band, and the ZOR mode is not affected by the position change of the probe feed. Thereby an off-center probe feed can be used to excite a TM01 mode with patch-like radiation pattern at the upper operation band, and its performance remains good stability when the size of the metal strip is varying. The equivalent circuit, electric field and current distributions of the proposed antenna are studied to investigate the principles of the ZOR and the TM01 modes, and all the results show that the two operation bands can be effectively and independently controlled. As a proof-of-concept, a circular patch antenna prototype with low profile of about $0.023~\lambda _{0}$ at 2.35 GHz is fabricated and tested. Good agreements between the measured and simulated results are achieved, showing monopole-like and patch-like radiation patterns within 2.28 - 2.40 GHz and 3.30 - 3.60 GHz, respectively, and the average realized gains are about 2.5 dBi and 8.5 dBi for the two operation bands.

Miniaturised triple‐band antenna loaded with complementary concentric closed ring resonators with asymmetric coplanar waveguide‐fed based on epsilon negative transmission line

This study presents an open-ended triple-band miniaturised metamaterial (MTM) inspired antenna based on the epsilon negative-transmission line (ENG-TL). The zeroth-order resonance (ZOR) and first-order resonance (FOR) characteristics are implemented using the ENG-TL theory. The proposed MTM antenna consists of rectangular and square-shaped complementary concentric closed ring resonator (CCCRR) in the left and right half of the asymmetric coplanar waveguide (CPW) ground plane, respectively. The CCCRR generates an extra coupling capacitance and inductance, which help for improving the gain at ZOR mode and better impedance matching at higher-order mode. The resonance characteristic of the antenna is controlled by the shunt elements due to its open-ended boundary condition. The proposed triple-band MTM antenna offers measured -10 dB impedance bandwidths of 8.54% (1.12-1.22 GHz), 10.25% (2.22-2.46 GHz) and 35.75% (2.94-4.22 GHz). All these three bands show good impedance matching with appropriate gain and high radiation efficiency and also having an omnidirectional pattern in the xz- plane and dipolar type pattern in the yz -plane. The designed antenna shows an overall dimension of 0.11 λ 0 × 0.11 λ 0 × 0.006 λ 0 at ZOR frequency (1.16 GHz).

Novel dual band patch antenna With Gap coupled composite right/left-handed transmission line

AbstractA novel low profile dual band patch antenna is presented. It consists of a composite right/left-handed transmission line (CRLH TL) unit cell gap coupled with the radiating edge of a rectangular patch antenna. The dual band behavior is achieved by coupling the zeroth order resonance mode of CRLH TL and TM10 mode of the patch antenna. It is shown that frequency ratio can be changed by varying the gap between the patch and CRLH TL unit cell. The proposed configuration enables frequency reconfigurability by changing the CRLH TL unit cell using a switch. A prototype of the antenna having frequency ratio f2/f1 = 1.08 is designed and fabricated. The proposed antenna shows measured S11 ≤ −10 dB bandwidth of 100 and 50 MHz at resonance frequencies of f1 = 4.84 and f2 = 5.22 GHz, respectively. A 2 × 2 dual band CRLH TL coupled patch array is also presented, showing more than 12.7 dBi gain at both resonance frequencies.

Dual-Polarized and Wide-Angle Scanning Microstrip Phased Array

In this communication, a novel microstrip phased array with dual-polarized and wide-angle scanning in the 2-D space is proposed. The element antenna consists of a mushroom-shaped patch and two circular patches. Each circular patch is connected with one feeding port. The mushroom-shaped patch is excited via capacitive coupling through the gaps between the mushroom-shaped patch and the circular patch. The zeroth-order resonance and TM010 mode resonance are simultaneously generated in the mushroom-shaped patch. The 3 dB beamwidth of the element antenna in the 2-D space is in the range between 110° and 125°. One $6 \times 6$ phased array based on the antenna element is designed, fabricated, and measured. The phased array shows the dual-polarized wide-angle beam scanning in a range of ±66° in both $x {z}$ and $y {z}$ planes with the scan loss of 3.5 dB.

Novel Two-Dimensional CRLH TL and its Application on Tri-Band Omnidirectional Antenna

Abstract A new type of two-dimensional composite right/left handed transmission line (2D CRLH TL) is proposed in this letter. Utilizing this structure, an antenna operating on GLONASS and WLAN based on dual zeroth-order resonance (ZOR) mode and first-order resonance (FOR) mode is designed and fabricated. By taking advantage of coaxially center feed and symmetric structure, nearly all omnidirectional radiations in XOY plane at three operating frequencies is obtained. Furthermore, the antenna gain has a high value of −1.27 dB in f1=1.60 GHz, −3.89 dB in f2=2.39 GHz and 0.67 dB in f3=5.12 GHz respectively.

Bandwidth enhancement of ZOR antenna by loading novel via-Less CRLH-TL unit cells

Novel via-less CRLH-TL unit cells loaded compact and bandwidth-enhanced zeroth-order resonant (ZOR) antennas have been designed and experimentally verified. Two CRLH-TL unit cells are designed and loaded in monopole antennas to enhance the bandwidth. The series capacitance of CRLH-TL unit cell is implemented with both interdigital capacitance/gap capacitance and shunt inductance is implemented with meander line inductance. The dispersion characteristics of the proposed unit cells are numerically calculated which follows CRLH-TL properties. Further, the conventional CRLH-TL unit cell metallic vias have been eliminated by using two novel techniques, which increases the fabrication flexibility. The compactness has been achieved by realizing ZOR mode and the resulting four open-ended ZOR antenna’s bandwidth is increased by realizing small shunt capacitance and large shunt inductance. Further, to increase its bandwidth, merging of ZOR mode to the higher and lower order modes into a single passband by realizing proper CRLH-TL unit cells has been done. The each proposed antenna has a compact dimension of 25 × 15 × 1.6 mm3 and S11 < −10 dB impedance bandwidths of 9.6 GHz, 9.7 GHz, 10 GHz and 9.6 GHz respectively. The optimum gain, good efficiency and desired radiation characteristics have been achieved for proposed antennas, which are most suitable for ultra-wideband applications. The CST-MWS has been used for the parametric study of the proposed antennas. A good agreement has been achieved between simulated and measured results.

UWB Metamaterial-based miniaturized planar monopole antennas

In this paper, ultra wide band (UWB) metamterial based compact planar antennas have been designed and experimentally verified. Four novel unit cells have been realized and each unit cell dispersion characteristics are numerically calculated which follows CRLH-TL properties. These four CRLH-TL unit cells are loaded into monopole antennas which result, four open-ended MTM antennas respectively. Further, a novel via free version of CRLH-TL unit cells have been designed, which increases the fabrication flexibility. The compactness has been achieved by realizing ZOR (zeroth order resonance) mode and its bandwidth is increased by realizing small shunt capacitance and large shunt inductance. Further, by optimizing CRLH-TL unit cells, two closely spaced zeroth-order and first-order resonance modes are merged into a single pass band, which gives wide bandwidth. The each proposed antenna has a compact dimension of 0.27 λ0×0.19 λ0×0.02 λ0 (22×15×1.6mm3), where λ0 is a free space wavelength at 3.8GHz. The four proposed antennas have S11<−10dB impedance bandwidths of 8.4GHz, 8.5GHz, 8.2GHz and 8.3GHz respectively. The optimum gain, good efficiency, desired radiation characteristics in frequency domain analysis and less distortion of waves in time domain analysis have been achieved for proposed antennas, which are most suitable for UWB applications. The CST-MWS has been used for the parametric study of the proposed antennas. A good agreement has been observed between simulated and experimental results.

Via-less CRLH-TL unit cells loaded compact and bandwidth-enhanced metamaterial based antennas

The via-less composite right hand left hand (CRLH)-TL unit cells loaded compact and bandwidth-enhanced metamaterial (MTM) antennas have been designed and experimentally investigated. Four novel unit cells are designed and its dispersion characteristics of the proposed unit cells are numerically calculated which follows CRLH-TL properties. Further, the conventional metallic vias of CRLH-TL have been eliminated to increase the fabrication flexibility. The four CRLH-TL unit cells are loaded into monopole antennas which result, four via-less open-ended MTM antennas respectively. Its ZOR (zeroth order resonance) bandwidth is increased by realizing small shunt capacitance and large shunt inductance. Further, to increase overall antenna bandwidth, merging of ZOR mode to the higher and lower order modes into a single pass band has been done by realizing proper CRLH-TL unit cells. The each proposed antenna has a dimension of 0.13λ0×0.08λ0×0.0085λ0, where the free space wavelength λ0 at 1.6GHz. The four proposed antennas have S11<−10dB fractional bandwidths (FBW) 173% (1–13.6GHz), 169% (1.2–14.5GHz), 158% (1.6–13.5GHz) and 158% (1.6–13.5GHz) respectively. The optimum gain and desired radiation characteristics have been obtained for all proposed antennas, which can be suitable for UWB applications. The CST-MWS has been used for the parametric study of the proposed antennas. A good agreement has been observed between simulated and experimental results.

Dual-Band Microstrip Circular Patch Antenna With Monopolar Radiation Pattern

A novel dual-band microstrip monopolar patch antenna with zeroth-order resonance is proposed and analyzed in this letter. The antenna is a combination of circular patch antenna with center-fed and circularly periodic mushroom units. With the zeroth-order resonant (ZOR) mode and ${\rm TM}_{02}$ mode, the proposed antenna can create horizontal magnetic loop currents on the patch, which lead to a low profile of $0.02\lambda $ at the low frequency band. The radiation mechanism of the proposed antenna is discussed. The antenna is fabricated on a double-layered printed circuit board (PCB) and center-fed by a 50- $\Omega $ SMA connector. Simulated and measured results show that the proposed antenna produces a stable monopole-like radiation pattern in two working frequency bands. The corresponding impedance bandwidths and gains are 0.75% and 5.1 dBi for the low frequency band and 20% and a range of 5.8–8 dBi for the high frequency band.

Dual-Band Antenna Integrating With Rectangular Mushroom-Like Superstrate for WLAN Applications

A rectangular mushroom-like superstrate structure is proposed to design an antenna for dual-band wireless local area network (WLAN) applications. The proposed antenna consists of an array of mushroom-like rectangular patches and a planar slot antenna. Based on the dispersion diagram analysis, the proposed antenna can operate in two bands: The lower band is from 2.3 to 2.98 GHz, with -10-dB bandwidth of 25.8%, which is corresponding to zeroth-order resonant (ZOR) mode, and the upper band is from 5.02 to 5.84 GHz, with -10-dB bandwidth of 15.1% and average realized gain of 6.9 dB at boresight. The proposed antenna is feasible to cover the specification for dual-band WLAN applications in the 2.4-GHz (2400-2484 MHz) and 5-GHz (5150-5825 MHz) bands. Furthermore, the proposed antenna has a low profile of 4.2 mm and compact size of 33 ×30 mm 2 , which is suitable for installation in wireless handheld devices. The simulated and measured results are in good agreement to verify the good performance of the proposed antenna.

Compact Circularly Polarized Antenna With Wide 3-dB Axial-Ratio Beamwidth

A compact circularly polarized antenna with wide 3-dB axial-ratio (AR) beamwidth is presented. The two pairs of radiators based on mu-negative transmission lines are applied and each radiator has a capacitor at the center and a pair of vias at both edges of the radiator to induce a zeroth-order resonance mode. The two radiators for x-polarized wave are orthogonally aligned to the other two radiators for y-polarized wave, and the 90 ° phase difference is realized by detuning the resonance frequencies of the corresponding radiators. In particular, a circular ground plane is adopted for the symmetrical radiation pattern and optimized to have the wide 3-dB axial-ratio beamwidth. Also, a dual-ground structure is studied to suppress back radiations caused by the compact ground. The 3-dB AR beamwidth is measured as 175 ° - 190 ° , and the measured gains are observed as 3.8 dBic at θ = 0 ° and 0.5 dBic ( - 0.5 - 1.2 dBic) at θ = 60 ° .

A Miniaturized ZOR antenna with enhanced bandwidth for WiMAX applications

In this article, a compact zeroth-order resonance (ZOR) antenna with extended bandwidth is presented. The proposed antenna consists of a rectangular and semicircular patch separated by gap G which is liable for initiating ZOR mode. The semicircular patch and ground planes are connected by a thin stripline, hence, via less coplanar metamaterial structure. The proposed antenna offers measured fractional bandwidth of 23.64% at ZOR frequency (fZOR = 3.60 GHz) with an average peak gain of 2.26 dB with 95.89% radiation efficiency over entire working band. The proposed antenna shows the overall footprint area of 0.276 λ0 × 0.129 λ0, where λ0 is the free space wavelength centered at 3.60 GHz. It also offers dipole like pattern in xz-plane and omnidirectional pattern in yz-plane at ZOR frequency. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:71–75, 2016

Design of dual‐bandpass filter using zeroth‐order resonance and Bragg frequency

This study presents a novel compact dual-bandpass filter using zeroth-order resonance and Bragg frequency of the composite right/left handed transmission line (CRLH-TL) resonator. By taking advantage of the Bragg frequency, two resonance modes are obtained with only one CRLH-TL unit cell. The equivalent circuit for the novel resonator is proposed and analysed. The resonance frequencies are given by using the circuit model and the input impedance is calculated. Dimensions of the resonator can be obtained based on the values of the lumped elements in the equivalent circuit. Compared with the conventional half-wavelength resonator, the size of the presented resonator is only about one-tenth of it. Then, the zeroth-order resonance and Bragg frequency modes are demonstrated using the dispersion curve. A dual-bandpass filter is designed to verify the resonator analysis. The source–load coupling is involved to improve the frequency selectivity of the filter. The fabricated filter is compact with a size of only 0.09 λg × 0.16 λg. The two central frequencies are located at 2.4/3.3 GHz and the filter has a wide upper stopband of over 4 GHz. Moreover, the fabricated filter has five transmission zeros and good frequency selectivity is observed.