Folded Monopole Antenna Research Articles

Low Profile Vertically Polarized Omnidirectional Wideband Antenna With Capacitively Coupled Parasitic Elements

This communication presents a low profile and electrically small wideband antenna with omnidirectional radiation pattern and vertical polarization. A novel design approach manipulating the topology of a low profile folded monopole antenna with capacitively coupled parasitic elements in the same plane is presented to achieve omnidirectional radiation pattern. The 10-dB return loss fractional bandwidth of 43% is achieved with the dimension of 0.2λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LF</sub> ×0.2λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LF</sub> ×0.06λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LF</sub> where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LF</sub> is the wavelength at the lowest frequency of the operation. Unlike the convention wideband λ/4 monopole antennas utilizing inductively coupled parasitic elements, the λ/2 folded monopole antenna allows for positioning the capacitively coupled parasitic elements in the middle of the antenna where maximum electric stored energy is formed. This, together with reducing the lateral dimension of the folded monopole antenna, enables the cancellation of radiated fields from electric currents in the horizontal plane of the proposed antenna, which is essential to achieve vertically polarized omnidirectional radiation. The compact parasitic elements introduce additional resonances that significantly increase the antenna bandwidth. Effects of design parameters on two resonant frequencies and impedance matching to a 50 Ω feed are investigated using the equivalent circuit model of the parasitic element and full-wave electromagnetic (EM) simulations. Based on this analysis, a design procedure to optimize the antenna topology is established.

Folded Monopole Antenna with Parasitic Element in Small Terminal for WiMAX and WLAN MIMO Systems

Folded Monopole Antenna with Parasitic Element in Small Terminal for WiMAX and WLAN MIMO Systems

Research on a Novel Folded Monopole With Ultrawideband Bandwidth

In this letter, a novel folded monopole antenna with an ultrawideband (UWB) bandwidth and omnidirectional radiation performance has been proposed. An inverted “S”-type structure was formed by folding the planar monopole, which not only realizes dimension reduction, but also contributes to a decrease in the size of the ground plane; the proposed monopole antenna, meanwhile, has a more circular radiation pattern with the frequency ratio of 3.4:1, compared to the planar monopole antenna. Simulation has been carried out together with the measurement of the fabricated antenna. Good agreement between the measured and simulated results can be observed, showing that the antenna is capable of working in the frequency range from 3.1 to 10.6 GHz with return loss less than -10 dB.

A Tunable Dual-Band Miniaturized Monopole Antenna for Compact Wireless Devices

A technique for producing miniaturized tunable planar monopole antennas for wireless communication applications is introduced. Miniaturization is achieved by optimizing the geometry of a pixelated metallic patch surrounding the monopole antenna. Tuning of the antenna is implemented by varying the capacitance of a varactor diode loaded between the pixelated metallic patch and the ground plane. The result is an ultra-compact, dual band, folded monopole antenna that fits into a hemisphere of radius λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /20 at 2.1 GHz. Varying the capacitance of the varactor diode enables the two resonance frequencies to be tuned simultaneously, covering multiple frequency bands for different wireless applications. A prototype antenna has been fabricated and measured, confirming the feasibility of the proposed design.

A Multi-Level Optimization Method Using PSO for the Optimal Design of an L-Shaped Folded Monopole Antenna Array

This study presents a multi-level optimization (MLO) method applied in particle swarm optimization (PSO) to solve a 3-objective optimization problem for an antenna array design consisting of two L-shaped folded monopole antennas (LFMAs) operating in the IEEE 802.11 b/g WLAN band (2400-2484 MHz). The method incorporates a simple concept whereby three sub-objective functions, representing the reflection coefficient S 11, the mutual coupling S 21, and the entire antenna volume of the LFMA array, are minimized one by one in the PSO to obtain an optimal LFMA array configuration that provides reduced size and higher antenna performance. The advantages of the proposed method, both in terms of deriving appropriate optimization results and reducing computational cost for the optimization problem, are demonstrated by comparing its performance with that of a conventional weighted aggregation (CWA) method, and a method using the concept of Pareto dominance (PD). The optimal LFMA array configuration obtained by the proposed method has a 10% resonant bandwidth ( S 11 ≤ -10 dB for 2.32-2.57 GHz), S 21 reduced to less than -15 dB in this band, and an antenna volume that was markedly decreased, to 28.5% of that of the original design.

Compact Ultrawideband Mimo Antenna for Mobile Applications

A new broadband multiple-input multiple-output (MIMO) antenna with good isolation and compact size is proposed. The proposed antenna consists of two G-shaped elements in the upper layer and two inverted L protrude branches and a T slot etched in ground which is used to reduce the mutual coupling. This planar antenna has a bandwidth of 100% with |S11| ≤ -10 dB from 2.26GHz to 6.78 GHz. The value of isolation between the two antenna elements is more than 22.5 dB in the whole band. The experimental results verify the simulations. This project presents an ultra-wideband MIMO antenna covering WCDMA, WLAN, WiMax and UWB bands for mobile handset applications. The designed antenna consists of a folded monopole antenna coupled with inverted-L element and meander lines. The proposed antennas are symmetrically placed on top part of the mobile handset ground for MIMO antenna technology. Meander lines are positioned between two antennas for improving the isolation in operation bands. The size of the designed MIMO antenna is 55mm × 13:5 mm. The isolation between two antennas is higher than 17.2 dB. Due to the compact size and ultra-wide bandwidth, it is good for a mobile handset antenna that has a limited space available.

A Folded Dual-Band Monopole Antenna for RFID System

A folded dual-band monopole antenna for 2.45 GHz and 5.8 GHz RFID tag applications is proposed in the present paper. It is formed by two folded monopole antennas for reducing the geometric size of the tag. One of them operates at 2.45 GHz, and the other operates at 5.8 GHz. The input impedance of the proposed antenna is designed to be conjugate matched to the chip impedance for the maximum power transfer. This antenna is modeled, analyzed, and optimized by HFSS. The simulation results demonstrate that the performances of the proposed antenna can satisfy the requirements of RFID system. The characteristics of the proposed antenna are simple structure, low cost, and small sizes.

Compact Folded Monopole Antenna Excited by a Conductor-Backed Coplanar Waveguide with Vias

A compact monopole antenna excited by a conductor-backed coplanar waveguide (CBCPW) is developed for wireless USB dongle applications. The proposed antenna has a compact dimension of 14 mm × 47.4 mm × 3.5 mm, which is suitable for a USB dongle housing. A slotted elliptical patch and a CBCPW with vertical vias are employed to achieve a further size reduction and an improved impedance bandwidth. The measurement result demonstrates that the fabricated antenna resonates from 2.25 GHz to 10.9 GHz, which covers all of the important wireless communication bands, including WiBro (2.3 GHz to 2.4 GHz), Bluetooth (2.4 GHz to 2.484 GHz), WiMAX (2.5 GHz to 2.7 GHz and 3.4 GHz to 3.6 GHz), satellite DMB (2.605 GHz to 2.655 GHz), 802.11b/g/a WLAN (2.4 GHz to 2.485 GHz and 5.15 GHz to 5.825 GHz), and ultra-wideband (3.1 GHz to 10.6 GHz) services. The radiation characteristics of the proposed antenna when attached to a laptop are tested to investigate the influence of the keypad and the LCD panel of the laptop.

Metamaterial-Inspired Wire Antennas

Three antennas for Wi-Fi 802.11n applications are presented. The first antenna is a dual-band antenna operating at the 2.4 GHz and the 5.5 GHz bands. This antenna is conceived from the zero-order resonating wire metamaterial antenna. By making a judicious choice for the capacitances and inductances of zero-order mode antenna, the new metamaterial-inspired wire antenna can resonate at two distinct frequencies. The simulated gain is 2 dBi and 4 dBi at lower and upper band, respectively. The two others designed antennas are the compact folded monopole antenna with 0.5 dBi gain, and the compact folded dipole antenna with 2 dBi gain. They were simulated using CST Microwave Studio full-wave simulator and measured.

A study on wideband L-shaped folded monopole antenna with parasitic element

A study on wideband L-shaped folded monopole antenna with parasitic element

A Fully SiP Integrated $V$-Band Butler Matrix End-Fire Beam-Switching Transmitter Using Flip-Chip Assembled CMOS Chips on LTCC

In this paper, a fully system-in-package (SiP) integrated V-band Butler matrix beam-switching transmitter (TX) is presented. The CMOS chips from differential process technologies are assembled on a low-temperature co-fired ceramic (LTCC) substrate carrier by flip-chip interconnects. The vertically embedded folded monopole antenna is designed and integrated into the LTCC. The array consisting of four identical monopole antennas and a Butler matrix for beam switching is realized on the LTCC for loss reduction. Four switched main beams are measured and agree well with simulation. This beam-forming TX shows the potential of the low-cost millimeter-wave SiP with CMOS chips.

Editor's Comments

The design of modern, practical antennas for mobile phones typically involves satisfying requirements that go beyond the straightforward operating parameters of the antenna in free space. For example, such additional requirements can include the over-the-air performance of the mobile phone in the presence of the user's hand and head, meeting SAR (Specific Absorption Rate) standards, and meeting hearing-aid compatibility (HAC) requirements. In their feature article, X. L. Chen, E. Ofli, N. Chavannes, and N. Kuster describe the use of a commercial Finite-Difference Time-Domain (FDTD)-based electromagnetic simulation software package and the genetic algorithm to optimize the design of mobile-phone antennas to meet such disparate real-world requirements. The article begins with a description of the FDTD software's capabilities, and the use of a genetic algorithm in such software to optimize an antenna design across a range of parameters. The optimization was parallelized using two networked computers. How the optimization method was applied to the antenna is explained. The authors then describe the cell phone modeled in the study, as well as the models used for the three types of antennas considered: a folded-monopole antenna, a planar inverted-F antenna (PIFA), and a folded inverted conformal antenna (FICA). The way these antennas were parameterized and details of the optimization approach are then explained. The optimized results of the simulations included the free-space performance of the antennas in the cell phone, the performance of the antennas in the cell phone in the presence of hand and head phantoms, the SAR for the cell phone, and the hearing-aid compatibility results. In addition to discussing what factors affected the results obtained, the authors also provide information on the number of simulations and the computational time required to produce the results. The article provides quite realistic examples of practical optimization problems faced by designers of cell-phone antennas, while also providing interesting insight into the performance of the types of antennas studied in realistic cell-phone usage scenarios.

A Compact Ultrawideband MIMO Antenna With WLAN Band-Rejected Operation for Mobile Devices

This letter presents an ultrawideband multiple-input–multiple-output (MIMO) antenna that covers the WCDMA (1.92–2.17 GHz), WiMAX (2.3, 2.5 GHz), WLAN (2.4 GHz), and UWB (3.1–10.6 GHz) bands for wireless device applications. The proposed antenna consists of a printed folded monopole antenna coupled with a parasitic inverted-L element, with an open stub inserted in the antenna to reject the WLAN (5.15–5.85 GHz) band that interferes with the UWB band. These two antennas are symmetrically arranged on a mobile device substrate. The <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 10-dB bandwidth of the designed antenna is 1.85–11.9 GHz without the WLAN band 5.15–5.85 GHz. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${ S}_{21}$</tex></formula> and the envelope correlation coefficient are lower than <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 17.2 dB and 0.18 in the operating bands, respectively. The size of the antenna is <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$55\times13.5 ~{\hbox{mm}}^{2}$</tex></formula> .

Bluetooth, WiMAX, UWB 시스템용 역 L형 무급전 소자 결합 프린트형 광대역 폴디드 모노폴 안테나

본 논문에서는 테블릿 및 노트북 컴퓨터에 적용될 수 있는 프린트형 광대역 폴디드 모노폴 안테나를 제안하였다. 제안된 안테나는 두 선로의 폭이 비대칭인 프린트형 폴디드 모노폴 안테나와 역 L형 무급전 소자를 결합하여 Bluetooth, WiMAX, UWB 시스템의 대역폭(2.3~10.6 GHz)을 수용할 수 있도록 설계하였다. 또한, 폴디드모노폴 안테나 내부에 반파장 오픈 스터브를 삽입하여 UWB 대역과 간섭을 일으키는 무선 랜 대역(5.15~5.85 GHz)을 차단하였다. 제작된 무선 랜 대역 차단 광대역 안테나의 -10 dB 대역폭은 2.27~10.6 GHz(4.7:1)이며, -10 dB 대역 저지 대역폭은 700 MHz(5.15~5.85 GHz, 12.72 %)로 측정되었다. 안테나의 이득과 효율은 차단 대역을 제외하고 각각 3.93 dBi와 81 % 이상으로 나타났으며, 차단 대역에서 이득은 -2 dBi(5.5 GHz) 효율은 14.65 %로 측정되었다. 안테나의 크기는 12.75(1 <TEX>${\lambda}$</TEX>/10)<TEX>${\times}$</TEX>12(1 <TEX>${\lambda}$</TEX>/11) <TEX>$mm^2$</TEX>(<TEX>${\lambda}$</TEX>는 2.3 GHz의 공기중 파장)로 테블릿 및 노트북의 작은 공간에 탑재하기에 적합한 크기를 가진다. 따라서 설계된 안테나가 테블릿 및 노트북 컴퓨터용 광대역 안테나로 적합함을 확인하였다. This paper presents a printed, wideband folded monopole antenna for laptop and tablet computer applications. The proposed antenna is designed to cover bandwidth(2.3~10.6 GHz) of Bluetooth, WiMAX, and UWB system by using the printed folded monopole antenna having asymmetrical line width coupling with a parasitic inverted- L element. Also, wireless LAN band(5.15~5.85 GHz) which interferes with UWB system is rejected by inserting half-wavelength open stub in the folded monopole antenna. -10 dB bandwidth of the fabricated wideband antenna is 2.27~10.6 GHz (4.7:1) and -10 dB band-rejected bandwidth is measured as 700 MHz(5.15~5.85 GHz, 12.72 %). The gain and efficiency of the antenna except for the rejected band are higher than 3.93 dBi and 91.89 % and are measured as -2 dBi and 14.65 % at 5.5 GHz which is band-rejected frequency. The size of the antenna is suitable to install for small space of tablet and laptop computers as 12.75(1 <TEX>${\lambda}$</TEX>/10)<TEX>${\times}$</TEX>12(1 <TEX>${\lambda}$</TEX>/11) <TEX>$mm^2$</TEX>(<TEX>${\lambda}$</TEX> is free space wavelength at 2.3 GHz). Therefore, we verified that the designed antenna is appropriate for wideband antenna of tablet and laptop PC applications.

Folded monopole LC-loaded antenna and its polarization reconfigurability

Folded monopole antenna loaded with the distributed inductors and capacitors is designed and characterized.The inductors and capacitor are realized by utilizing meanderline strips and the interdigitated structure, respectively. The resonance characteristics of the antenna are essentially determined by the uniquely arranged distributed elements, not by the length of the radiator, such that an electrically small structure can be realized. The designed antennas having a radiator length of 0.078 λ0 have good reflection characteristics and reasonable radiation gains of 0.29 dBi peak. The effect of the ground size on the resonant characteristics of the antennas is also investigated. Although the radiation characteristics are dependent upon the ground size, the variation of the resonance frequency was minimal. By utilizing the radiation characteristics depending upon the ground size of the folded monopole antenna with LC-loadings, a polarization reconfigurable antenna can also be realized. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1197–1201, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25999

Compact wideband folded monopole antenna coupled with parasitic inverted-L element for laptop computer applications

A wideband folded monopole antenna coupled with a parasitic inverted-L element for 2.3-10.6-GHz band laptop computer applications is presented. The designed antenna is composed of a printed folded monopole with an asymmetrical line width and a parasitic inverted-L element. The input impedance is matched by widening the line width of the folded monopole and adjusting the space between the parasitic inverted-L element and the folded monopole. The measured -10-dB bandwidth is 4.85:1 (2.27-11-GHz), and the size of the antenna is 13.75 (1-/10) mm-12 (1-/11) mm (where --2.27-GHz).

Design and Implementation of Internal Multi-band Folded Monopole Antenna for Mobile Station

In this paper, we designed and implemented an internal multi-band folded monopole antenna for mobile handset. The proposed antenna covers Global System for Mobile Communications (GSM900: 880~960 MHz), Digital Communications System (DCS: 1710~1880 MHz), US-Personal Communications Service (US-PCS: 1850~1990 MHz), Bluetooth(2400~2484 MHz), WiMAX(3400~3600 MHz), and Wireless Local Area Network (WLAN: 5150~5350 MHz, 5725~5875 MHz) band for Voltage Standing Wave Ratio <TEX>$(VSWR)\;{\le}\; 3$</TEX>. The measured peak gains of the implemented antenna are -1.78dBi at 920MHz, 2.72dBi at 1795MHz, 2.25dBi at 1920MHz, 2.34dBi at 2442MHz, 2.11 dBi at 3550MHz, and 2.04 dBi at 5250MHz.

The Mutual Coupling Reduction between Two J-Shaped Folded Monopole Antennas for Handset

In this study, we propose a method to reduce the mutual coupling between two J-shaped folded monopole antennas (JFMAs), which cover the IEEE 802.11 b/g (2400-2484MHz) band. First, the change in mutual coupling with the spacing between the two antenna elements is investigated by considering two feeding models, and the effects of changes in the coupling on the antenna efficiency are studied. Subsequently, we try the method to reduce mutual coupling, the method involves the use of a bridge line that links the two antennas. The mutual coupling can be significantly reduced and the total antenna efficiency can be improved by linking two shorting strips with the bridge line. In a past study, we had found that in the case of L-shaped folded monopole antennas (LFMAs), the mutual coupling and antenna efficiency vary with the linking location on the bridge line. Moreover, we compare the characteristics of the LFMA and JFMA and show that the JFMA is effective when miniaturized.

Bowtie-Feed Broadband Monopole Antenna for Laptop Applications

In this letter, a metal-wire-cutting folded monopole antenna design for laptop applications in Long-Term Evolution (LTE) operation in the bands 1, 7, 8, and 20 is presented. This antenna consists of a folded tab monopole with bowtie feed and shorted structure, making it easy to combine omnidirectional, multiband, and broad bandwidth. The experimental results of the constructed prototype are provided.

A New Magneto-Dielectric Material Loaded, Tunable UHF Antenna for Handheld Devices

In this letter, the impact of a magneto-dielectric resonator on a DVB-H antenna is investigated. A frequency reconfigurable antenna using a folded monopole antenna structure and varactor diodes is proposed. Two different designs are realized with and without the resonator. A measured instantaneous -6-dB bandwidth wider than 8 MHz is obtained continuously between 470 and 862 MHz for both prototypes. Design methodology is described. Measured return loss, gain, directivity, and radiation pattern are presented for different frequencies.