Multiband monopole antenna loaded with Complementary Split Ring Resonator and C-shaped slots

This paper presents a compact semi circular monopole antenna loaded with Complementary Split Ring Resonator (CSRR) and two C-shaped slots is proposed for Global System for Mobile Communication (GSM), Worldwide Interoperability for Microwave Access (WiMAX) and C-band applications. The size of the proposed antenna is 20 × 20 × 0.5 mm³. The resonance frequency of WiMAX (3.73 GHz) is achieved by introducing CSRR slots on the ground plane. To realize multiband characteristics for GSM (1.77 GHz), WiMAX (2.6 GHz) and C-band (4.15 GHz), two C-shaped slots of quarter wavelength are introduced in radiating element. The extraction procedure of negative permittivity for the proposed CSRR is discussed in detail. The proposed antenna is fabricated and measured. Simulated and measured results are in good agreement. Omni directional radiation pattern is obtained in H-plane and bi directional radiation pattern is obtained in E-plane. Parametric study of CSRR and C-shaped slot are examined to obtain best results. The proposed antenna has significant advantages, including low profile, miniaturization ability, and good impedance matching.     

Double stub microstrip fed two element Rectangular Dielectric Resonator Antenna for multiband operation

This article presents a design of multiband Rectangular Dielectric Resonator Antenna (RDRA) using two elements with different aspect ratio. The proposed DRA is excited by means of micro-strip feedline with double stubs which not only improves the bandwidth of each band but also achieves good impedance matching. The proposed DRA operates at “C” band, “WLAN” and “X” band frequencies and yields wide bandwidth of about 6.5%, 13.5% and 17.4% respectively. Two Rectangular DRs of completely different aspect ratio and double stub microstrip feeding achieve this multiband operation. The designed antenna is very compact and has a volume of 1737 mm³ only. It provides stable radiation patterns in all the three bands and has a maximum gain of 6.35 dBi with radiation efficiency of more than 82% over the operating band of frequencies. The proposed antenna has been studied, analyzed and optimized using Ansoft HFSS simulation software. The designed antenna is fabricated, tested and compared with other multiband designs. Good agreement is achieved between simulated and measured ones.     

A novel 5.8 GHz quasi-lumped element resonator antenna

In this paper, a novel quasi-lumped element resonator antenna is presented. The proposed antenna consists of the interdigital capacitor in parallel with a straight line inductor and is fabricated on Duroid RC4003C circuit board. The entire arrangement was fed by a coaxial feed at a frequency of 5.8 GHz. The size, bandwidth and radiation patterns were studied. The proposed antenna exhibits better impedance bandwidth and significant size reduction in comparison with similar results obtained from the conventional microstrip patch antenna with similar feeding technique and resonant frequency. The size of the proposed antenna structure is 5.8 × 5.6 mm² and experimental results are shown to be in good agreement with the design simulation.     

Wideband L-shaped printed monopole antenna

A wideband dual-polarized L-shaped printed monopole antenna (LSPMA) is presented. The antenna operates around the center frequency of 4 GHz. This L-shape printed antenna provides wide impedance bandwidth over 4.7 GHz. Experiments have been carried out to validate the simulated results of input impedance and dual polarized radiation patterns.     

Wheel shaped modified fractal antenna realization for wireless communications

A compact, low profile circular fractal patch antenna with low latency, low cost, high speed and multiband is presented. With the help of CST Microwave Studio Suite TM the proposed structure has been designed and analyzed. The simulated results are fixed experimentally. The suggested antenna has dimension of 32 × 36 mm² (W × L) and operating from 2.93 GHz–9.53 GHz with VSWR ≤ 2. The aerial is assembled on FR-4 (ε_r = 4.4) substrate with a thickness of substrate 1.25 mm. Detailed parametric studies of the antennas have been carried out. This microstrip fed antenna is suitable for ultra wideband (UWB), S, C and part of the X band applications.     

Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications

This article presents a small, low-profile planar microstrip antenna that is applicable for both WLAN and WiMAX applications. The goal of this paper is to design an antenna which can excite triple-band operation with appreciable impedance bandwidth to combine WLAN/WiMAX communication specifications simultaneously in one device. The designed antenna has a compact size of 10 × 26 mm². The proposed antenna consists of an inverted U-shaped slot radiator and a defected ground plane. Overall the design method and parametric study found appropriate dimensions, which provides three distinct bands I from 2.40 to 2.52, II from 3.40 to 3.60 and III from 5.00 to 6.00 GHz that covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. Finally, a prototype antenna was fabricated and experimentally characterized to verify the design concept as well as to validate the simulation results. Thus the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN and WiMAX frequency bands.     

A printed monopole ellipzoidal UWB antenna with four band rejection characteristics

An antenna design with four band rejection characteristics for UWB application is demonstrated. The proposed unique UWB antenna has shape of an embedded ellipse at top of trapezoidal patch (named as ellipzoidal), 50 Ω impedance microstrip line feed and a truncated beveled ground plane. To realize four band stop characteristics, three inverted U-shaped and a single I-shaped slots each of half guided wavelength are utilized on radiating element. The fabricated antenna has dimensions of 27 mm × 36 mm × 1.6 mm. This four band notched ellipzoidal UWB antenna has measured frequency bandwidth 2.8–14 GHz for magnitude of S₁₁ < −10 dB level. The measured ellipzoidal antenna exhibits four band rejection characteristics for magnitude of S₁₁ > −10 dB at 3.55 GHz for WiMAX band (3.26–3.9 GHz), 4.55 GHz for ARN band (4.35–5.05 GHz), 5.7 GHz for WLAN band (5.5–6.65 GHz) and 8.8 GHz for ITU-8 band (7.95–9.35 GHz). The proposed ellipzoidal UWB antenna maintains omnidirectional radiation pattern, gain, linear phase response, <1 ns group delay, and transfer function in the whole UWB operating bandwidth except at notched frequency bands.     

Compact wideband omnidirectional UHF antenna for TV white space cognitive radio application

This paper presents design and analysis of a compact wideband omnidirectional antenna for application in TV white space cognitive radio. The proposed antenna mainly consists of a monopole, a pair of parasitic elements, and a brief impedance matching network, all etched on an FR4 substrate. To obtain physical insight, an equivalent circuit is modelled and analysed to reveal the contribution of each part of the antenna to its bandwidth enhancement. Performance of the antenna is evaluated by simulations, and then further validated by experiments. Experimental results show that the antenna has an impedance bandwidth (voltage standing wave ratio less than 2) ranging from 460 MHz to 870 MHz, as well as omnidirectional radiation patterns in H-plane through the whole band.     

Dual band monopole antenna based on metamaterial structure with narrowband and UWB resonances with reconfigurable quality

In this article, an Ultra Wide Band (UWB) monopole antenna based on Metamaterial (MTM) unit cell with reconfigurable feature has been developed. The proposed antenna covers 3.1–10.6 GHz for UWB applications and it has a reconfigurable narrow-band for L-band (1.27 GHz) and wireless applications. The gaps in Split Rings Resonator (SRR) element are made for the Left-hand capacitance and Ω-shape strip layer by four via junctions are used for Left-hand inductance. The antenna is printed on FR-4 low cost substrate with relative permittivity of 4.4 and thickness of 1.6 mm. The total size of the antenna is 40 mm × 40 mm. The simulation is carried out using HFSS commercial full-wave software. In addition, the experimental results are presented and compared with simulated results. The antenna gives a maximum peak gain of 6 dBi with Omni-Directional radiation pattern and high efficiency of more than 70%. By embedding four switches in Ω-shape strip layer, a reconfigurable antenna has been successfully designed for wireless applications with sufficient qualification. The monopole part covers the UWB spectrum and the CRLH is responsible for the controllable narrowband resonance. The simulation and experimental results are confirmed by the numerical results.     

A miniaturized Vivaldi antenna by loading with parasitic patch and lumped resistor

A miniaturized Vivaldi antenna is presented in the paper. On the basis of original antenna, the miniaturized Vivaldi antenna applies parasitic patch and lumped resistor to improve impedance characteristics. The proposed load can expand the lower operating frequency to 1.96 GHz without changing antenna dimensions. The size of antenna is set as 43 × 40 mm². This size is about 0.28λ_L × 0.26λ_L, where λ_L is the free space wavelength at 1.96 GHz. The loaded Vivaldi antenna is fabricated and measured. The simulated and measured results clarify the viability and effectiveness of the proposed design. The measured impedance bandwidth (VSWR ≤ 2) is from 2 GHz to more than 18 GHz. In addition, the measured radiation patterns and a peak gain between −1 and 9 dB can be obtained in the band of 2–18 GHz.     

Broadband proximity fed ring microstrip antenna arrays

Various gap-coupled array configurations of ring microstrip antennas and rectangular slot cut ring microstrip antennas with proximity fed slot cut ring microstrip antenna for larger bandwidth and gain are proposed. The rectangular slot in ring patch reduces its orthogonal TM₀₁ and TM₀₂ mode resonance frequencies and along with TM₁₀ modes of fed and parasitic ring patches, yields broadband response. The gap-coupled configuration with ring patch and slot cut ring patch yields bandwidth of nearly 430 MHz with broadside radiation pattern and peak gain of more than 9 dBi. By gap-coupling ring patches along all the edges of proximity fed pair of slot cut ring patch, a 3 × 3 ring microstrip antenna array is realized. It yields bandwidth of more than 460 MHz with peak gain of more than 10 dBi. To further improve upon the bandwidth, a 3 × 3 array of ring patches in which rectangular slot is first cut on the edges of ring patch which are gap-coupled along x-axis and further cut inside the patches which are gap-coupled along x and diagonal axes, is proposed. Both of these configurations yield bandwidth of more than 500 MHz (>45%) with a peak gain of around 10 dBi.     

Time domain analysis for foldable thin UWB monopole antenna

In this paper, the time domain analysis of an Ultra Wide Band antenna flexible circular monopole antenna is presented. The antenna is fabricated on liquid crystalline polymer flexible substrate with a compact geometry that makes it suitable for wearable applications under different bending conditions. The antenna is fed by coplanar waveguide transmission line and has a compact total size of 40 × 22 mm². Moreover, the antenna has good radiation efficiency (97%) over the bandwidth. The presented antenna has a good performance over the operating spectrum for straight and bending configurations. The design principals along with simulation and experimental results are presented in this contribution.     

Design and analysis of implantable CPW fed bowtie antenna for ISM band applications

A novel implantable coplanar waveguide (CPW) fed crossed bowtie antenna is proposed for short-range biomedical applications. The antenna is designed to resonate at 2.45 GHz, one of the industrial-scientific-medical (ISM) bands. It is investigated by use of the method of moments design equations and its simulation software (IE3D version 15). The size of the antenna is 371.8 mm³ (26 mm × 22 mm × 0.65 mm). The simulated and analyzed return losses are −23 and −25 dB at the resonant frequency of 2.45 GHz. We have analyzed some more performances of the proposed antenna and the results show that the proposed antenna is a perfect candidate for implantation. The proposed antenna has substantial merits like low profile, miniaturization, lower return loss and better impedance matching with high gain over other implanted antennas.     

New frequency-reconfigurable microstrip antenna composed of organic semiconductor polymer

A novel frequency-reconfigurable microstrip antenna composed of organic semiconductor polymer (P3HT) is proposed. Resonance frequency of the antenna is tuned in 6.8–7.73 GHz band, by changing the light illumination intensity of a 5 W/cm² white light source. Behavior of the antenna under different light intensities is investigated and compared to a reference copper antenna. Measured radiation patterns are identical in higher and lower resonant bands. Measured radiation efficiency and gain of the proposed antenna are compared in higher and lower bands. The results indicate that, it is possible to obtain reasonable performance albeit with modest radiation efficiencies.     

Resonant characteristics of aperture type FSS and its application in directivity improvement of microstrip antenna

In this paper, we propose an aperture type frequency selective surface (FSS) by employing an array of 12 × 12 unit cell elements and its resonant characteristics is analyzed. A resonant cavity antenna is then formed by the ground plane substrate and the FSS superstrate. The high reflective behavior of the proposed FSS at an offset of the resonance is then utilized for improving the performance of this cavity antenna. The impedance bandwidth and directivity are improved up to 0.66 GHz and 8.95 dBi, simultaneously at an optimum gap of 17.6 mm between the antenna substrate and FSS superstrate. For validation purpose, prototypes of both patch antenna and FSS, are fabricated and characterized. A fairly good agreement is achieved between the measured and simulated results.     

Miniaturized active stepped impedance planar inverted-F antenna using common ground

This paper presents a compact active integrated antenna (AIA) comprising of class-A power amplifier (PA) and stepped impedance planar inverted-F antenna (PIFA). In the proposed design, a common ground is used for both PA and PIFA, resulting a compact antenna of size 0.14λ₀ × 0.11λ₀ × 0.01λ₀ (λ₀ is free space wavelength at 0.85 GHz). Moreover, it is demonstrated that by using the stepped impedance radiator the operating frequency of the active PIFA is shifted down from its natural resonant frequency of 1.36 GHz to 0.85 GHz, offering an extensive size reduction of 80%. This active integration increases the passive antenna gain through the effective loading of the antenna to the power amplifier. The measured result indicates that the active and passive antennas achieved the gain of 15.7 dB and 3.81 dBi, respectively after the integration. In addition, the maximum SAR value of antenna is found to be 0.64 W/kg.     

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 × 1.6 mm³), where λ₀ is a free space wavelength at 3.8 GHz. The four proposed antennas have S₁₁ < −10 dB impedance bandwidths of 8.4 GHz, 8.5 GHz, 8.2 GHz and 8.3 GHz 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.     

Performance enhancement of patch antenna array for 5.8 GHz Wi-MAX applications using metamaterial inspired technique

Though a microstrip patch antenna has advantages of low profile and structural planarity, but a single microstrip patch antenna has limitation of low gain and narrow bandwidth. To overcome these problems, multi-layer structures are used. The antenna performance can further be enhanced, if multi-layer structures are designed for array of patch antennas. Moreover, the simultaneous improvement of gain and bandwidth, which are two conflicting parameters, is another challenge. To meet these challenges, this article proposes a microstrip patch antenna array, inspired with a superstrate – comprising of Split Ring Resonators (SRR) and wire strips. Gain and bandwidth of 4.3 dBi and 425 MHz, respectively, is achieved by an unloaded array at IEEE 802.16a 5.8 GHz Wi-MAX band. However, by covering this array with the proposed superstrate, gain and bandwidth of 12.1 dBi and 780 MHz, respectively, is obtained, thus providing the gain improvement of 7.8 dBi and bandwidth enhancement of 355 MHz. Fabrication and testing of the proposed antenna is done for comparing simulated and measured results. Equivalent circuit of this newly devised array has been designed and discussed.     

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 1.6 GHz. The four proposed antennas have S₁₁ < −10 dB fractional bandwidths (FBW) 173% (1–13.6 GHz), 169% (1.2–14.5 GHz), 158% (1.6–13.5 GHz) and 158% (1.6–13.5 GHz) 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.