Asymmetric CPW-fed SRR patch antenna for WLAN/WiMAX applications

In this paper, a compact asymmetric coplanar waveguide (CPW) feed with split-ring resonator (SRR) is proposed to resonate at dual-band operations for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The asymmetric CPW-fed SRR patch (ACSP) antenna consists of a meander line, square-shaped split ring, and CPW ground plane. The proposed ACSP antenna resonates at two operating frequencies, namely, 2.48 GHz (2.4–2.74 GHz) and 3.49 GHz (3.25–3.64 GHz) with reflection coefficients (S₁₁) of −16.65 dB and −32.67 dB, respectively. The measured results agree closely with the simulation results of the proposed antenna.     

Compact UWB monopole antenna with quadruple band notched characteristics

ABSTRACT

A compact planar Ultrawideband (UWB) monopole antenna with quadruple band notch characteristics is proposed. The proposed antenna consists of a notched rectangular radiating patch with a 50 Ω microstrip feed line, and a defected ground plane. The quadruple band notched functions are achieved by utilising two inverted U-shaped slots, a symmetrical split ring resonator pair (SSRRP) and a via hole. The fabricated antenna has a compact size of 24 mm × 30 mm × 1.6 mm with an impedance bandwidth ranging from 2.86 to 12.2 GHz for magnitude of S₁₁ < ?10 dB. The four band notched characteristics of proposed antenna are in the WiMAX (worldwide interoperability for microwave access) band (3.25–3.55 GHz), C band (3.7–4.2 GHz), WLAN (wireless local area network) band (5.2–5.9 GHz) and the downlink frequency band of X band (7–7.8 GHz) for satellite communication are obtained. The measured and simulation results of proposed antenna are in good agreement to achieve impedance matching, stable radiation patterns, constant gain and group delay over the operating bandwidth.     

Dual Band-Notched Small Monopole Antenna with Enhanced Bandwidth for UWB Applications

This article proposes a novel printed monopole antenna for ultra wideband applications with dual band-notch function. The antenna consists of a disc-shaped radiating patch with a pair of folded strips arms, and a ground plane with a two L-shaped conductor backed plane, which provides a wide usable fractional bandwidth of more than 140 % (2.6–14.43 GHz). In order to generate single band-notch characteristics, we use a modified disc-shaped radiating patch with a pair of folded strips arms also by using this modified radiating patch, additional resonance is excited and hence much wider impedance bandwidth can be produced, especially at the higher band. By adding two L-shaped conductor backed plane in the ground plane a dual band notch function is achieved. The measured results reveal that the presented dual band-notch monopole antenna offers a very wide bandwidth with two notched bands, covering all the 5.2/5.8 GHz WLAN, 3.5/5.5 GHz WiMAX and 4 GHz C bands. The designed antenna has a small size of $12\times 18\,\hbox {mm}^{2}$ .     

Microwave Dielectric Properties of BiCu<Subscript>2</Subscript>PO<Subscript>6</Subscript> Ceramics with Low Sintering Temperature

A BiCu₂PO₆ microwave dielectric ceramic was prepared using a solid-state reaction method. As the sintering temperature increased from 800°C to 880°C, the bulk density of BiCu₂PO₆ ceramic increased from 6.299 g/cm³ to 6.366 g/cm³; the optimal temperature was 860°C. The best microwave dielectric properties [permittivity (? _r ) = ～16, a quality factor (Q × f) = ～39,110 GHz and a temperature coefficient of resonant frequency (τ _f ) = ～?59 ppm/°C] were obtained in the ceramic sintered at 860°C for 2 h. Then, TiO₂ with a positive τ _f (～+400 ppm/°C) was added to compensate the τ _f value. The composite material was found to have a near-zero τ _f (+2.7 ppm/°C) and desirable microwave properties (? _r  = 19.9, Q × f = 24,885 GHz) when synthesized at a sintering temperature of 880°C. This system could potentially be used for low-temperature co-fired ceramics technology applications.     

Wideband CPW-Fed Spiral-Shaped Slot Antenna for Wireless Applications

A new compact design of CPW-fed wideband (WB) spiral-shaped slot antenna is proposed. The proposed antenna has a compact size with overall dimensions 37-33 mm and is fabricated on FR4 substrate with dielectric constant ? _r = 4.4 and thickness h = 1.6 mm. With the different length of the spiral-shaped slots, simulated and experimental results of the antenna are suitable for WB operations. The–10 dB bandwidth of the WB antenna from measurement is approximately 115.2% (2.36–8.53 GHz). The proposed antenna provides nearly omni-directional radiation characteristics. The new antenna configuration operates in several different bands: 2.4, 3.5, 5.2, 5.5, and 5.8 GHz covering 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The results for S₁₁, far-field H- and E-plane radiation patterns and gain of the proposed antennas are presented and discussed. The agreement between measured results and full-wave simulation validates the feasible configuration of the proposed antennas.     

Metamaterial inspired quad band circularly polarized antenna for WLAN/ISM/Bluetooth/WiMAX and satellite communication applications

A CPW fed metamaterial inspired Quadband circularly polarized antenna is presented in this article. The proposed antenna consists of defected ground structure with a radiating stub, which is at opposite side of the feedline. A waveguide mode of analysis is carried out for split ring resonator (SRR) and complimentary split ring resonator (CSRR) to enhance the properties of metamaterials. The proposed antenna analysis is taken iteration wise and used FR-4 Material as the substrate material with Ɛ_r = 4.4 and analysed using ANSYS electromagnetic desktop. The designed antenna projecting the peak gain of 4.8 dB and it is working in the application bands of WLAN/ISM/Bluetooth at 2.4 GHz, 5.8 GHz and 3.35 WiMAX band, X-band downlink satellite communication system (7.25–7.75 GHz) and ITU band (8–8.5 GHz) with fractional bandwidth of about 70%. Proposed antenna exhibits circular polarization at 2.39–2.55 GHz, 3.05–3.1 GHz, 4–5 GHz and 6.3–6.64 GHz respectively. To know the signal integrity of the antenna, time domain analysis is carried out for identical antennas in two conditions (face to face and side by side) with the help of CST microwave studio. The designed antenna showing excellent correlation in measurements with respect to simulation results.     

Implementation of Vertex-Fed Multiband Antenna for Wireless Applications with Frequency Band Reconfigurability Characteristics

In this paper authors present the design and analysis of split ring resonator based multiband antenna for wireless applications with frequency-band reconfigurable features. The proposed design has octagonal shape SRR structure fed at vertex as radiating section and rectangular shape switchable slotted ground part. The antenna has dimensions of 44?×?39?×?1.6 mm³ and fabricated on FR4 substrate. The proposed structure exhibit hexa operating resonance characteristics at 3.3, 5.0, 5.8, 6.6, 9.9 and 15.9 GHz to cover the wireless standards at lower WiMAX, upper WLAN, super extended C-band, middle X band and lower K_U band respectively. Antenna achieve the frequency band reconfigurability characteristics by inserting PIN diode in slotted ground (reclined L-shaped) as triple/hexa resonant bands during OFF/ON switching state of PIN diode. An acceptable gain, stable and consistent radiation patterns with low cross polarization and good impedance matching are obtained at targeted frequency bands of proposed design.

     

Dual band microstrip patch antenna array loaded with split ring resonators and via holes

Reduction in antenna size by using multi-band radiators play a vital role in the miniaturization of present world wireless handheld devices, as dual band behaviour of the antennas result in the integration of more than one communication standard in a single system and thus, saving the installation space required for separate antennas. In this context, this communication presents a shorted-pin dual band metamaterial inspired microstrip patch antenna array. Under the unloaded conditions, the traditional patch antenna array resonates at 5.8 GHz with gain of 9.8 dBi and bandwidth of 540 MHz. However, when each patch of this traditional antenna array is loaded with split ring resonator (SRR) and a metallic via hole is introduced in the patch, the same antenna array produces an additional resonant frequency in IEEE 802.11b/g/n 2.45 GHz Wi-Fi band with bandwidth and gain of 290 MHz and 5.6 dBi, respectively, while the initial resonant frequency (i.e. 5.8 GHz) gets shifted to IEEE 802.11ac 5 GHz Wi-Fi band, providing the gain and bandwidth of 11.4 dBi and 510 MHz, respectively. The proposed antenna array has been fabricated, and the measured results are presented to validate the proposed array. Moreover, the equivalent circuit of the proposed antenna array has been designed and analyzed to validate the simulated, measured and theoretical results. Attainment of dual band characteristics by incorporating the metamaterial with single band traditional patch antenna array makes this structure novel, as this has been achieved without any extra hardware cost, size and loss of structural planarity. Also, both the frequency bands of this proposed metamaterial inspired antenna array possess considerable gain and bandwidth.     

Conformal Band Notched Circular Monopole Antenna Loaded with Split Ring Resonator

This article presents the design and analysis of conformal circular monopole antenna with split ring resonator to get frequency notch characteristics in the wideband. Split ring resonators placed on one side of the substrate and complementary split ring resonators placed on the other side of the substrate at defected ground structure, which yields the frequency notch characteristics with respect to the microstrip feeding. Dual notch band characteristics are obtained between 4–4.3 and 7.3–8.1 GHz. The analyzed conformal characteristic of the antenna supports excellent constant reflection coefficient characteristics over the band at different angles. The impedance and radiation characteristics of the antenna model is analysed in simulation along with unit cell analysis of the SRR and the measured results are providing good agreement with them.     

Design and Simulation of a Novel Micromachined Frequency Reconfigurable Microstrip Patch Antenna

In this paper, a novel model of a frequency reconfigurable microstrip patch antenna based on MEMS (microelectromechanical system) technology is introduced. Fabrication process of the proposed antenna is comprised of bulk and surface micromachining. Patch of the antenna is deposited over a silicon platform. The platform is created by structuring the silicon membrane which is formed through bulk micromachining of a silicon chip. The patch and the platform beneath it are discretized to facilitate their vertical displacement over underside air gap. Thermal actuation is used as driving mechanism. Operational mechanism of the antenna is such that by downward relocation of the patch, its resonant frequency shifts downward. Thermal actuators are connected to the platform and applying voltage to them cause downward shift in resonant frequency of the antenna. FEM (finite element method) simulations confirm mechanical and microwave performances of the antenna which are investigated by theoretical analyses. From mechanical point of view, antenna has tolerable mechanical stability and microwave point of view indicates that return losses are good (below $-$ 10 dB) and radiation patterns are very close to each other with reasonable gains. Moreover VSWR is less than 2 throughout the frequency tuning range. In the proposed antenna by applying a CMOS compatible voltage in the range of 0–4.5 V to each thermal actuator, the resonant frequency of the antenna shifts from 17.37 GHz in up-sate position to 15.07 GHz in down-state position. As a result of this frequency shift, a frequency tuning range of 2.3 GHz with bandwidths of 3.9 % in up-state and 1.4 % in down-state positions is achieved.     

Angled Split-Ring Artificial Magnetic Conductor for Gain Enhancement in Microstrip Patch Antenna for Wireless Applications

A multiband rectangular microstrip patch antenna integrated with angled split- ring artificial magnetic conducting (AMC) structure is proposed. In order to achieve high gain, directivity and radiation efficiency, an \(3\times 2\) array of proposed angled split-ring patches which has multiple in-phase reflection phase characteristics at S-band (2–4 GHz) is presented as a reflector. A rectangular microstrip patch antenna integrated with the proposed angled split-ring AMC is fabricated, tested and its parameters are compared with the microstrip patch antenna backed with a flat metal sheet, and microstrip patch antenna integrated with conventional split-ring AMC structure. The presence of high scattered field amplitude between the angled arms lead to improved radiation characteristics and make the antenna more suitable for real-time wireless applications. The antenna attains 2.138 dBi increment in gain and 1.87 dBi increment in directivity when it is backed with the proposed angled split-ring artificial magnetic conducting structure instead of a flat metal sheet. A good pact is obtained between the simulated and the measured results.     

Analysis of a high frequency and wide bandwidth active polyphase filter based on CMOS inverters

An active polyphase filter capable of high frequency quadrature signal generation has been analyzed. The resistors of the classical passive polyphase filter have been replaced by transconductors, CMOS inverters (F. Tillman and H. Sjöland, Proceedings of the Norchip Conference (pp. 12–15), Nov. 2005; Analog Integrated Circuits and Signal Processing, 50(1) 7–12, 2007). A three-stage 0.13 μm CMOS active polyphase filter has been designed. Simulations with a differential input signal show a quadrature error less than 1° for the full stable input voltage range for frequencies from 6 GHz to 14 GHz. Phase errors in the differential input signal are suppressed at least three times at the output. Corner simulations at 10 GHz show a maximum phase error of 3° with both n- and pMOS slow, in all other cases the error is less than 0.75°. The three-stage filter consumes 34 mA from a 1.2 V supply. To investigate the robustness of the filter to changes in inverter delay, an inverter model was implemented in Verilog-A. Linear c _in and g _in were used, whereas g _m , c _out , and g _out were non-linear. It was found that the filter could tolerate substantial delays. Up to 40° phase shift resulted in less than 1.5° quadrature phase error at the output.     

一种新型小尺寸三陷波超宽带天线设计

文中提出了一种新型小尺寸具有三陷波特性的UWB天线。所设计的天线基本几何结构由50 Ω馈电线、圆形辐射贴片、缺陷地和一对开口谐振环组成,通过在天线的圆形辐射贴片上内嵌一对Y型贴片、地板上蚀刻出U型贴片和一对开口谐振环实现三陷波特性,天线的尺寸为30 mm×30 mm×16 mm。仿真和测试结果表明,该天线29~107 GHz的频段内回波损耗＜-10 dB,在37~42 GHz、515~5825 GHz和79~84 GHz3个频段内具有陷波特性,分别有效抑制了C频段的卫星系统、WLAN系统和X频段卫星系统对超宽带系统的干扰。在除3个阻带频段外的其余UWB工作频段范围内,有着良好的辐射方向特性和稳定的增益。仿真结果和实验结果表现出了良好的一致性。     

High Efficiency and Wideband 300 GHz Frequency Doubler Based on Six Schottky Diodes

A high efficiency and wideband 300 GHz frequency doubler based on six Schottky diodes is presented in this paper. This balanced doubler features a compact and robust circuit on a 5-μm-thick, 0.36-mm-wide, and 1-mm-long GaAs membrane, fabricated by LERMA-C2N Schottky process. The conversion efficiency is mainly better than 16% across the wide bandwidth of 266–336 GHz (3 dB fractional bandwidth of 24%) when pumping with 20–60 mW input power (P _in) at the room temperature. A peak output power of 14.75 mW at 332 GHz with a 61.18 mW P _in, an excellent peak efficiency of 30.5% at 314 GHz with 43.86 mW P _in and several frequency points with outstanding efficiency of higher than 25% are delivered. This doubler served as the second stage of the 600 GHz frequency multiplier chain is designed, fabricated, and measured. The performance of this 300 GHz doubler is highlighted comparing to the state-of-art terahertz frequency doublers.     

Investigation on 2D photonic crystal-based eight-channel wavelength-division demultiplexer

In this paper, eight-channel wavelength-division demultiplexer (WDDM) is proposed and designed using two-dimensional photonic crystal (2DPC) ring resonator whose corresponding functional parameters such as transmission efficiency, resonant wavelength, Q factor are investigated. The proposed structure consists of bus waveguide, dropping waveguide and square ring resonators. Eight different channels are dropped by altering the cavity size and radius of the defect rods. The plane-wave expansion (PWE) and finite-difference time-domain (FDTD) methods are employed to analyse the photonic band gap (PBG) of periodic and non-periodic structure and to arrive normalized transmission spectra, respectively. The resonant wavelengths of eight-channel demultiplexers are 1496.9, 1502.3, 1506.9, 1512.3, 1515.0, 1520.4, 1525.3 and 1530.6 nm. The average transmission efficiency, Q factor and spectral width of proposed demultiplexer are 81%, 825 and 1.8 nm, respectively. The mean channel spacing is about 4.2 nm. The size of the demultiplexer is small; hence, it can be utilized for photonic integrated circuits (PIC).     

Effect of Rare Earth Elements on Electromagnetic and Microwave Absorption Properties of Fe-Based Alloys

The RE₂Fe₁₇ (RE = Ce, Pr, Nd, Sm) and La_xPr_2?xFe₁₇ (x = 0.0, 0.1, 0.2, 0.3, 0.4) alloys were synthesized by arc smelting and high-energy ball milling methods. The phase structure, morphology, magnetic properties and electromagnetic parameters of the powders were characterized by x-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer, respectively. The results reveal that the lattice parameters a and c and unit-cell volume V of the La_xPr_2?xFe₁₇ alloys increase linearly upon the La content. The minimum absorption peak frequency shifts towards a lower-frequency region upon the La content. And the minimum reflection loss and saturation magnetization of the La_xPr_2?xFe₁₇ alloys decrease upon the La content, while the minimum reflection loss of Pr₂Fe₁₇ and La_0.4Pr_1.6Fe₁₇ alloy of the 2.0 mm coating thickness reaches about ?13.65 dB and ?7.15 dB at 5.92 GHz and 3.6 GHz, respectively.     

Multiband Multiple Elliptical Microstrip Patch Antenna with Circular Polarization

In this paper a compact low profile elliptical fractal patch antenna for high gain and multiband is presented which resembles Lorentz fractal shape. By introducing fractal on ellipse patch multiband applications are achieved. With the help of CST Microwave Studio Suite TM the proposed structure has been designed and analyzed. The simulated results are confirmed experimentally. The suggested antenna has a dimension of 40?×?55 mm² (L?×?W) and resonant frequencies obtained are 1.7, 3.2, 3.9, 5.9, 7.8, 8.6, 9.7, 11.4 and 12.6 GHz with VSWR?≤?2. The aerial is assembled on FR-4 (ε_r?=?4.4) substrate with thickness of substrate 1.6 mm. This antenna holds applications in many satellite communication transmissions, some Wi-Fi devices, cordless telephones, and weather radar systems.     

基于SRR结构的陷波超宽带天线设计

针对超宽带系统易受窄带信号干扰的问题,设计了一种新颖的基于金属开口谐振环(SRR)结构的平面超宽带陷波天线。在天线的辐射贴片上加载U形缝隙,实现了其陷波特性。利用仿真软件研究了U形缝隙的物理尺寸对其陷波特性的影响,并对所设计的超宽带天线进行了制作和测量。结果表明,所制天线在超宽带系统3.1~10.6GHz工作频段的电压驻波比(VSWR)小于2,在WLAN频段具有良好的陷波特性,有效地抑制了超宽带通信系统与窄带通信系统之间潜在的干扰。     

A New Type of Miniature Ultra-Wideband Band-Pass Filter with Coplanar Waveguide Fed

A novel miniature ultra-wideband (UWB) bandpass filter with coplanar waveguide (CPW) fed is proposed. The size of the filter is reduced largely because of combining the wideband couple gap and parallel-coupled CPW line (not cascading multiple resonator), and the length of realized filter is only 0.42 λ _g0 (λ _g0 is the guiding wavelength at central frequency). The measured insertion loss is less than 2.0 dB, and the group delay variation is less than 0.2 ns within the UWB passband. Basic agreement between the simulated and measured results has been achieved.     

Double MOS Loaded Circular Microstrip Antenna with Airgap for Mobile Communication

A novel model of a wide frequency range double MOS loaded circular microstrip patch antenna with airgap between ground plane and substrate is proposed. In this structure two metal oxide semiconductor (MOS) devices are loaded on the patch to enhance the operating frequency range of antenna. To investigate the antenna, different parameters such as resonance frequency, input impedance, frequency agility, VSWR, radiation pattern etc. are calculated and simulated. The resonant frequency of proposed 10 mm radius patch is upward shifted from 5.2 to 6.8 GHz using 1 mm airgap and by loading MOS, antenna can be tuned down to 1.27 GHz operating frequency, which leads to compactness and tunability of antenna. Proposed antenna can be tuned between 1.27 and 6.8 GHz frequency of operation which makes the antenna highly suitable for wide frequency range of mobile communication. The proposed double MOS loaded antenna possessed 82.94 % frequency agility. The antenna is worth for GPS, WLAN, UMTS, and WiMAX operations.