Conventional Monopole Research Articles

A new broadband dual‐layer monoplolar circular patch antenna with slot coupling

ABSTRACTA new center‐fed dual‐layer circular patch antenna is proposed for bandwidth enhancement. The proposed antenna consists of a circular ground plane, a slotted circular patch on the lower layer and a parasitic circular patch on the top layer. The slotted circular patch is fed with a coaxial probe. With the help of the slots introduced to the lower patch, the parasitic patch on the top layer is strongly coupled. With the strong coupling of the two patches, a broadband is obtained. A prototype is fabricated. The measured results show that a wide bandwidth of 25% is obtained. Within the bandwidth, the measured peak gain is in the range of 6.2–8.7 dBi. The antenna produces an omnidirectional pattern in the horizontal plane, similar to that generated by a conventional monopole antenna. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:40–43, 2017

Experimental study on the performance of an azimuthal acoustic receiver sonde for a downhole tool

ABSTRACTA new azimuthal acoustic receiver sonde with a body and corresponding circuits was designed for a downhole tool. The 64‐sensor receiver sonde holds eight receiver stations that can be combined into at least 64 three‐sensor receiver subarrays. As a result, the receiver sonde can use different sensor combinations instead of different transducer types to produce multiple modes, including a phased azimuthal reception mode and conventional monopole, dipole, and quadruple modes. Laboratory measurements were conducted to study the performance of the azimuthal acoustic receiver sonde for a downhole tool, and the experimental results indicate that the receiver sonde provides a consistent reception performance. Individual sensors receive similar time‐domain waveforms, and their corresponding frequency bands and sensitivities are consistent within the measurement errors of around 5%. The direction of the reception main lobe is approximately parallel to its exterior normal direction. In addition, a receiver subarray with three sensors receives waveforms that have higher energy and narrower beamwidths. For individual sensors, the angular width of the dominant reception lobe is 191.3° on average, whereas that of the individual receiver subarrays is approximately 52.1° on average. The amplitude of the first arrival received by the receiver subarray centred at the primary sensor directly pointing to the source is approximately 2.2 times the average amplitude of the first arrivals received by the other receiver subarrays in the same receiver station. Thus, the maximum amplitude of the waveforms received by the receiver subarrays can be used to determine the direction of the incident waves. This approach represents a promising method for determining the reflector azimuth for acoustic reflection logging and three‐dimensional acoustic logging.

Experimental study on the surface wave driven plasma antenna

This experimental study examines the characteristics of a plasma antenna. For these experiments, we use a surface wave excitation at 450MHz with RF power levels up to 40W and gas pressure between 0.25mb and 0.6mb. Measurements of visible light from the plasma column confirm that the length of the antenna is linearly proportional to the square root of the excitation power and the proportionality factor is a function of gas pressure. Observations of the VSWR of the antenna show that decreasing the excitation power and increasing the pressure lead to the reduction of the resonant length of the antenna. The gain of the plasma antenna was measured between 110 and 300MHz. The results show that the gain of a plasma antenna is considerably less than a conventional monopole antenna.

MINIATURIZED SLOTTED GROUND UWB ANTENNA LOADED WITH METAMATERIAL FOR WLAN AND WIMAX APPLICATIONS

This paper presents a miniaturized ultra wideband (UWB) antenna with metamaterial for WLAN and WiMax applications. For miniaturization of UWB antenna resonating 3.1–10.6 is designed Ghz using fractalization of the radiating edge and slotted ground structure approach. A miniaturization of active patch area and antenna volume is achieved up to 63.48% and 42.24% respectively, with respect to the conventional monopole UWB antenna. This antenna achieves a 143% impedance bandwidth covering the frequency band from 2.54GHz to 15.36GHz under simulation and 132% (2.95–14.28 GHz) in measurement. The electrical dimension of this antenna is 0.32λ × 0.32λ (38mm×38mm) at lower frequency of 2.54GHz. As per IEEE 802.11a/b/g and IEEE 802.16e standards, WLAN (2.4–2.5 GHz, 5.150–5.250 GHz, 5.725–5.825 GHz), WiMAX (3.3–3.8 GHz) bands are achieved by using slotted ground structure and metamaterial rectangular split ring resonator. The proposed antenna is fabricated on FR4 substrate of thickness 1.6mm and a dielectric constant 4.3 and tested. The proposed antenna yields a −10 dB impedance bandwidth of about 11.1% (2.39–2.67 GHz), 59.1% (2.87–5.28 GHz) and 7.4% (5.58–6.01 GHz) under simulation and 4.5% (2.41–2.52 GHz), 51.1% (3.12–5.26 GHz) and 3.8% (5.69– 5.91GHz) in measurement for 2.4, 3.5 & 5 and 5.8GHz bands respectively. Stable radiation patterns with low cross polarization, high average antenna gain of 3.02 dBi under simulation and 2.14 dBi in measurement and measured peak average radiation efficiency of 76.6% are observed for the operating bands. Experimental results seem in good agreement with the simulated ones of the proposed antenna.

Bandwidth and radiation specifications enhancement of monopole antennas loaded with split ring resonators

New broadband antennas loaded with split ring resonators (SRR) are proposed and investigated. The results illustrate that by loading the conventional monopole antennas with an asymmetrical meander lines SRR, a lower resonance frequency mode can be excited. The dimensions of the SRR have been selected to provide a resonance close the resonance of the monopole antennas. The results illustrate that when both resonance coincide the antennas bandwidths and radiation properties can be enhanced. The length and width of the antennas are 25 × 10 − 2 λ 0 × 11 × 10 − 2 λ 0 and 25 × 10 − 2 λ 0 × 21 × 10 − 2 λ 0 at 4 GHz for monopole antennas, and 29 × 10 − 2 λ 0 × 21 × 10 − 2 λ 0 at 2.9 GHz for both monopole antennas loaded with SRR. For antennas without SRR loading, maximum of measured gains and efficiencies are 3.6 dBi and 78.5% for F-antenna, and 3.9 dBi and 80.2% for T-antenna, hence they appear at 5 GHz. For antennas with SRR loading, these parameters are 4 dBi and 81.2% for F-antenna, and 4.4 dBi and ∼83% for T-antenna, which appeared at 6 GHz. By implementing the meander lines SRR as a matching load on the monopole antennas, the resulted antennas cover the measured frequency bandwidths of 2.9–6.41 GHz and 2.6–6.6 GHz (75.4 and ∼87% fractional bandwidths), which are ∼2.4 and 2.11 times more than monopole antennas with an approximately same in size.

CPW-Fed Multiband Monopole Antenna Loaded With DCRLH-TL Unit Cell

A coplanar waveguide (CPW)-fed multiband monopole antenna based on loading one dual composite right/left-handed (DCRLH) transmission line (TL) unit cell is presented. The antenna works at 3.22 GHz, 4.57 GHz, and 5.71 GHz. The first resonant frequency (3.22 GHz) is a little lower than the first resonance (3.38 GHz) of the corresponding conventional monopole, the second (4.42 GHz) is much lower than the second resonance (9 GHz) of the conventional monopole, and the third one achieves the zeroth-order (ZOR) resonance. Also the electromagnetic (EM) simulation results demonstrate that the proposed antenna has satisfactory omni-directional radiation patterns with reasonable gains. Finally the antenna is fabricated and measured; measurements and EM simulations are in good agreement.

Bandwidth Enhancement Technique of the Meandered Monopole Antenna

A small dual-band monopole antenna with coplanar waveguide (CPW) feeding structure is presented in this paper. The antenna is composed of a meandered monopole, an extended conductor tail, and an asymmetrical ground plane. Tuning geometrical structure of the ground plane excites an additional resonant frequency band and thus enhances the impedance bandwidth of the meandered monopole antenna. Unlike the conventional monopole antenna, the new resonant mode is excited by a slot trace of the CPW transmission line. The radiation performance of the slot mode is as similar as that of the monopole. The parametrical effect of the size of the one-side ground plane on impedance matching condition has been derived by the simulation. The measured impedance bandwidths, which are defined by the reflection coefficient of −6 dB, are 186 MHz (863–1049 MHz, 19.4%) at the lower resonant band and 1320 MHz (1490–2810 MHz, 61.3%) at the upper band. From the results of the reflection coefficients of the proposed monopole antenna, the operated bandwidths of the commercial wireless communication systems, such as GSM 900, DCS, IMT-2000, UMTS, WLAN, LTE 2300, and LTE 2500, are covered for uses.

Easy installation CPW-fed technique for fan-beam array antenna using grounded reflector for wireless applications

A fan-beam linear array antenna employing a non-parasitic grounded reflector, a new Coplanar Waveguide (CPW)-fed network, and Grounded Coplanar Waveguide (GCPW) radiation elements is presented. This fan-beam antenna is achieved using a four-element conventional non-planar monopole integrated with CPW line, which is perpendicularly connected to CPW feed network. In addition, the grounded reflector is vertically connected to the ground part of CPW feed network. These three main parts together produce a fan-beam antenna that can satisfy beneficial input impedance, radiation patterns, and gain bandwidth requirements in the frequency range 3.2–3.66 GHz. This array covers applications of 3.3 and 3.5 GHz WiMAX (Worldwide Interoperability for Microwave Access) operating bands. Also, combining a non-planar GCPW monopole antenna as an array with a non-parasitic grounded reflector and CPW feed network provides designers with an advantageous fan-beam pattern to be generated. In addition, the reflector height is reduced to half by the concept of image theory. As a consequence, the spatial dimension of the antenna will be reduced. Therefore, this combination results in a cheap, lightweight, and easy installing non-planar printed array antenna at high frequency bands. Comparisons are made between results obtained with and without a reflector array antenna.

Azimuthally acoustic logging tool to evaluate cementing quality

An azimuthally sensitive acoustic bond tool (AABT) uses a phased arc array transmitter that can provide directionally focused radiation. The acoustic sonde consists of a phased arc array transmitter and two monopole receivers, the spaces from the transmitter being 0.91 m and 1.52 m, respectively. The transmitter includes eight transducer sub-units. By controlling the high-voltage firing signal phase for each transmitter, the radiation energy of the phased arc array transducer can be focused in a single direction. Compared with conventional monopole and dipole transmitters, the new transmitter provides cement quality evaluation with azimuthal sensitivity, which is not possible with conventional cement bond log/variable density log tools. Laboratory measurements indicate that the directivity curves for the phased arc array and those computed theoretically are consistent and show good agreement. We acquire measurements from a laboratory cistern and from the field to validate the reliability and applicability of the AABT. Results indicate that the AABT accurately evaluates the azimuthal cement quality of case-cement interfaces by imaging the amplitude of the first-arrival wave. This tool visualizes the size, position and orientation of channeling and holes. In the case of good case-cement bonding, the AABT also evaluates the azimuthal cementing quality of the cement formation interface by imaging the amplitude of formation waves.

A novel a-shaped monopole-like slot antenna for ultrawideband applications

A novel A-shaped monopole-like slot antenna is presented. The proposed antenna consists of a A-shaped radiating patch in place of the conventional monopole patch antenna to achieve ultrawideband (UWB) frequency. The ground plane is also modified by cutting rectangular slots to resonate at lower band of UWB. The antenna is practically fabricated and simulated. Measured results shows a good agreement with simulated results. The prototype with an overall size of 25 × 25 × 1.6 mm3 achieves good impedance matching, almost constant gain, stable radiation patterns, and constant group delay over an entire operating bandwidth. The designed antenna offers a measured bandwidth of 9.6 GHz (2.9–11.5 GHz) which covers entire UWB band. The proposed antenna has a compact size, good radiation characteristics, ultrawide bandwidth, and good time-domain behaviors to satisfy the requirement of the current wireless communication systems. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1826–1829, 2014

MULTIBAND ANTENNA BASED ON LOADING A CPW-FED MONOPOLE WITH ONE CRLH-TL UNIT CELL

A Coplanar Waveguide (CPW)-fed monopole loaded with Composite Right/Left Handed Transmission Line (CRLH-TL) unit cell is presented in this letter. Multiband is achieved due to the nonlinear dispersion relation of the CRLH-TL unit cell. The CRLH-TL unit cell supports a fundamental LH wave (phase advance) at lower frequencies and a RH wave (phase delay) at higher frequencies. By loading CRLH-TL unit cells with a conventional monopole, the resonant frequency of higher order mode can be decreased, and zeroth-order mode or even negative-order mode can be achieved. As a result, the proposed antenna operates at 1.43GHz, 2.58GHz, 3.31GHz and 4.4GHz. Finally the modifled antenna is fabricated and measured; measurements and EM simulations are in a good agreement that conflrms the proposed theory.

RF MEMS 소자를 이용한 MIMO 안테나 설계

본 논문에서는 다중 입출력(Multiple-Input Multiple-Output: MIMO) 무선 기계에 대한 안테나의 설계를 제안하였다. 제안된 안테나는 다양한 LTE(Long Term Evolution) 서비스 대역을 다룬다; 밴드(band) 17(704~746 MHz), 밴드 13(746~787 MHz), 밴드 5(824~894 MHz), and 밴드 8(880~960 MHz). 제안된 주(main) 안테나는 광대역 동작을 위해 역 L-형태의 슬릿(slit)을 가지고 있다. 그리고 LTE 부(sub) 안테나는 스위치(switch)를 결합한 루프(loop) 안테나 구조에 기초를 두었고, 논리 회로에 의해서 공진 주파수가 조절될 수 있다. LTE 수신 안테나에 대한 조절 기술은 원하는 대역의 실현을 위해, 그리고 임피던스(impedance) 조절을 위해 RF MEMS(Micro-Electro Mechanical System)를 사용하였다. 두 개의 제안된 안테나는 서로 수직으로 편파되기 때문에 원하는 주파수 대역에서 두 안테나는 -20 dB 이하의 격리도 특성을 가지며, 두 안테나 사이의 상관 계수(Envelope Correlation Coefficient: ECC) 특성은 0.06 이하의 매우 낮은 값을 가진다. 제안된 안테나는 통합된 LTE 다중 입출력 시스템의 단말기에 적용이 가능하다. In this letter, a new approach is proposed for the design of a multi antenna for MIMO wireless devices. The proposed antenna covers various LTE(Long Term Evolution) service bands: band 17(704~746 MHz), band 13(746~787 MHz), band 5(824~894 MHz), and band 8(880~960 MHz). The proposed main antenna consists of a conventional monopole antenna with an inverted L-shaped slit for wideband operation. The proposed the LTE sub antenna is based on a switch loaded loop antenna structure, with a resonance frequency that can be controlled by capacitance of a logic circuit. The tuning technique for the LTE Rx antenna uses a RF MEMS(Micro-Electro mechanical system) to match the impedances to realize the bands of interest. Because the two proposed antennas are polarized orthogonally to each other, the ECC(Envelope Correlation Coefficient) characteristic between two antennas was measured to be very low (below 0.06) with an isolation characteristic below -20 dB between the two antennas in the operating overall LTE bands. The proposed antenna is particularly attractive for mobile devices that integrate LTE multiple systems.

An M‐shaped monopole‐like slot UWB antenna

ABSTRACTAn M‐shaped monopole‐like slot Ultra wideband (UWB) antenna is proposed for UWB applications. The proposed antenna usages, an M‐shaped radiator in place of the conventional monopole patch antenna to achieve UWB frequency. The ground plane is also modified by cutting rectangular slots. Therefore, the ground plane works like a radiator that resonates at lower band of UWB. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with compact overall size of 36 mm × 36 mm × 1.6 mm achieves good impedance matching, constant gain, and stable radiation patterns over an operating bandwidth of 2.38–12.40 GHz (10.02 GHz). © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:127–131, 2014

A CPW‐fed hexagonal‐shape monopole‐like UWB antenna

ABSTRACTA novel CPW‐fed hexagonal‐shape monopole‐like ultrawideband (UWB) antenna is proposed for UWB applications. The proposed antenna posses a method to minimize the monopole antenna by using a hexagonal shape over the conventional monopole patch antenna to lower the height of the antenna. The ground is vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with very compact overall size of 25 × 23 × 1.6 mm3 achieves good impedance matching, stable radiation patterns, and constant group delay over an operating bandwidth of 2.71–12.61 GHz (9.9 GHz). © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2582–2587, 2013

A CPW‐FED compact inverted L‐strip UWB microstrip antenna

AbstractA novel CPW‐fed compact inverted L‐strip ultra wideband (UWB) microstrip antenna is proposed for ultra wide band applications. The proposed antenna possesses a method to minimize the monopole antenna by loading of inverted L‐strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of 25 × 25× 1.6 mm3 achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6–13.04 GHz (10.44 GHz). © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1584–1589, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27651

Flexible and Compact AMC Based Antenna for Telemedicine Applications

We present a flexible, compact antenna system intended for telemedicine applications. The design is based on an M-shaped printed monopole antenna operating in the Industrial, Scientific, and Medical (ISM) 2.45 GHz band integrated with a miniaturized slotted Jerusalem Cross (JC) Artificial Magnetic Conductor (AMC) ground plane. The AMC ground plane is utilized to isolate the user's body from undesired electromagnetic radiation in addition to minimizing the antenna's impedance mismatch caused by the proximity to human tissues. Specific Absorption Rate (SAR) is analyzed using a numerical human body model (HUGO) to assess the feasibility of the proposed design. The antenna expresses 18% impedance bandwidth; moreover, the inclusion of the AMC ground plane increases the front to back ratio by 8 dB, provides 3.7 dB increase in gain, in addition to 64% reduction in SAR. Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas. Furthermore, it offers a compact and flexible solution which makes it a good candidate for the wearable telemedicine application.

An ISM/UWB Antenna with Offset feeding and Slotted Ground Plane for Body-centric Communications

An offset-fed ISM/Ultra-wideband (UWB) antenna with a slotted ground plane designed for on-body communications is presented in this paper. The antenna consists of a radiator very close to a square shape, a feed line slightly offset from the middle along the radiator side and three rectangular slots at the top edge of the ground plane. The offset feed line is used to improve the radiation pattern for on-body communications and the slots on the ground plane are used to improve impedance matching of the antenna. The antenna is studied using computer simulation. For verification of simulation results, the antenna is fabricated and measured. Simulated and measured results show good agreements in terms of reflection coefficient, gain, efficiency and radiation pattern. Measured results show that the antenna can achieve a wide bandwidth from 2.38 to 14.5 GHz with more omnidirectional radiation patterns in the E-plane than conventional monopole, making it a potential candidate for on-body communications using UWB.

A MICROSTRIP-FED MULTIBAND SPIRAL RING MONOPOLE ANTENNA WITH IMPROVED RADIATION CHARACTERISTICS AT HIGHER RESONANT FREQUENCIES

A novel approach for the design of a compact multiband monopole antenna for improving radiation characteristics at higher resonant frequencies is presented. The proposed structure consists of a conventional printed monopole loaded with spiral ring resonators and fed by microstrip. When at higher resonant frequency, the electrical length of the conventional monopole antennas is relatively large and the surface currents distribute on the patch periodically which will degrade the omnidirectional property. To achieve good radiation characteristics at the upper bands, two spiral ring strips are inserted into the microstrip line on the difierent layer and connected through via hole. Thus, the direction of surface currents on the spiral ring strips changes with the alteration of spiral structure and their efiects on the radiation pattern are reduced. The radiation pattern is mainly contributed by the surface current on the microstrip line and very good stable radiation pattern can be obtained within all the operating bands. In comparison to the previous printed strip monopole structures, the miniaturized Antenna dimension is only about 28 mm£20 mm£1mm. The experimental results show that the proposed antenna can provide operating bands which meet the required bandwidths speciflcation of 2.4/5.2GHz WLAN and 3.5GHz WiMAX standard. Detailed design considerations of the proposed Antenna are described, and both the simulated and measured results of the proposed Antenna are also presented and discussed.

A CPW-Fed Compact UWB Microstrip Antenna

A novel coplanar waveguide (CPW)-fed compact ultrawideband (UWB) microstrip antenna is proposed for ultrawideband applications. The proposed antenna posseses a method to minimize the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$25 \times 25 \times 1.6\ {\hbox{mm}}^3$</tex></formula> achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6-13.04 GHz (10.44 GHz).

Slot Antenna for Metal-Rimmed Mobile Handsets

This letter introduces a 15.5 × 56.5-mm2 planar slot antenna operated under surroundings of an unbroken metal rim in mobile handsets. The height of the slot antenna is shortened, and the bandwidth for low band is expanded to cover both GSM850 and GSM900. This antenna provides a solution for planar unbroken metal-rimmed handsets and can be operated in five wireless communication bands (i.e., GSM850, GSM900, DCS1800, PCS1900, and UMTS bands). Good performances on return loss, radiation pattern, efficiency, and gain are obtained over these five operating bands. Hand effect of this slot antenna is also studied by comparison to the conventional monopole antenna.