Folded Monopole Antenna Research Articles

Thermopneumatic Liquid Metal Radiofrequency Switch Actuated by Low‐Boiling‐Point Fluid

Existing radiofrequency (RF) switches used in reconfigurable antennas often encounter performance issues such as high insertion loss, low isolation, and nonlinear effects of the switch. To address these issues, this article presents a liquid metal RF switch that utilizes a heated low‐boiling‐point fluid (LBPF) to drive the movement of a eutectic gallium‐indium alloy (EGaIn) plunger to turn the switch on/off. The operating principle of the switch is to use the pressure difference generated by the liquid–vapor phase change of the LBPF to make the EGaIn plunger to contact with, or disconnect from the copper electrodes of the switch. The performances of the RF switches actuated by different LBPFs are respectively investigated, and the results show that all RF switches have millisecond response times, and the contact resistances are as low as 0.14 mΩ. In addition, good RF performances are achieved, with an insertion loss of less than 3 dB and isolation of more than 17 dB in the frequency band from 0 to 2 GHz, and no nonlinear effects. This study also validates the performance of the proposed switch for frequency reconfiguration of a folded monopole antenna.

Small-size multiband printed monopole antenna for wireless applications

AbstractA small-size multiband antenna with 14 bands is presented in this paper for wireless applications. The studied antenna mainly consists of a folded monopole antenna and an M-shaped structure. Furthermore, the antenna has a simple design with a compact dimension of 26.8 × 10.8 mm2. The studied antenna is printed on FR4 substrate with a depth of 0.8 mm and fed by a coaxial cable. The −10 dB bandwidths measured are 210 MHz (1200–1410 MHz), 100 MHz (2200–2300 MHz), 193 MHz (3000–3193 MHz), 180 MHz (3330–3510 MHz), 390 MHz (4110–4500 MHz), 4971 MHz, 577 MHz (5300–5877 MHz), and 700 MHz (7100–7800 MHz), which can cover 3G/4G/5G/Wi-Fi/WiMAX, C, and S bands. The gain and efficiency of the presented antenna are 1.3–4.00 dBi and 46%–60.2%, respectively.

A Dual-Band Antenna for LTE/mmWave Mobile Terminal Applications

In this communication, a dual-band antenna is proposed, which integrates a millimeter-wave (MMW) substrate-integrated dielectric resonator antenna (SIDRA) beam-steerable array and long-term evolution (LTE) folded monopole antenna (FMA). The SIDRA, which is a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times4$ </tex-math></inline-formula> tightly arranged DRA array with zero edge-to-edge spacing, is developed in the clearance area of the FMA. Hence, the two antennas not only share the same substrate but also share the same aperture. The performance of FMA will not deteriorate by properly locating the SIDRA array. An antenna prototype was fabricated and measured, and the rationality of the design was verified. The LTE FMA can cover the band of 1.78–2.62 GHz (38.2%) and achieve a peak gain of 3.9 dBi, while the MMW array can cover the band of 26.4–29.8 GHz (12.2%) and achieve a peak gain of 10 dBi. The MMW array can support beam-steering angles of ±45°. The high space utilization of the proposed design strategy makes the dual-band antenna suitable for the fifth-generation (5G) mobile terminal applications.

A Frequency Reconfigurable Folded Antenna for Cognitive Radio Communication

In this work, a spectrum-sensing monopole antenna was used to operate in different frequency bands for cognitive radio applications. The proposed antenna consists of a folded monopole antenna with a partial ground plane, and it can be used for various wireless technologies operated at various frequencies from 1.5 to 3.5 GHz. The suggested antenna was printed on a RO4003 substrate with 3.38 permittivity and an overall size of 60 × 60 × 0.813 mm3. To achieve reconfigurability of the antenna, PIN diodes (HPND-4005) were inserted at different lengths along the antenna to obtain the desired performance. The antenna was fabricated and experimentally tested to validate the simulation outcomes, and distinct consistency between the simulation and measurement outcomes was obtained. Computer simulation tool (CST) software was used to design and simulate the suggested antenna and then the model was fabricated to validate the simulation outcomes.

Far-Field Radiation Characteristics of Folded Monopole Antennas over a Conducting Ground Plane

Folded monopole structures have been used for many applications, including low-frequency electromagnetic wave transmission and reception. However, the literature on these antenna types is quite limited. Folded monopole antennas are mathematically complex compared to conventional monopole or dipole antennas since every fold introduces a new set of design parameters. This work studied the far-field radiation characteristics of multi-folded monopole antennas operating at 75 MHz in terms of their radiated power concerning the frequency, the far-field directivity of the electric field, and the effect of each design parameter on the far-field radiation power. According to the results, folding a monopole antenna multiple times increases its effective length, making this antenna a suitable candidate for applications where the antenna height is restricted. Additionally, the ground-to-wire separation has the biggest effect on radiated power. In both single-fold and two-fold cases, doubling the ground-to-wire separation increased the radiated power by 0.2 W compared to the other models with the same number of folds. As for the challenges, the impedance mismatch between the source and antenna causes a significant amount of power reflection; hence, suitable impedance matching is required to reduce reflected power.

A folded monopole antenna with variable input impedance by connecting additional elements

A folded monopole antenna with variable input impedance by connecting additional elements

Low-Profile Broadband Antenna With Pattern Diversity

A pattern diversity antenna with low profile and wideband operation is proposed in this letter. The topology combines a 3-D folded monopole antenna together with a differential L-plate fed patch antenna. The monopole antenna is realized by a pair of bent hexagon-shaped plates, which can provide a conical pattern in the horizontal plane. A common top hat is capacitively loaded to reduce the overall height of the monopole antenna. This hat is excited as a microstrip antenna by differential feeding plates, which achieves a broadside radiation pattern. The operating band of the proposed antenna is in the range of 1.65-2.7 GHz (48%), covering the GSM1800/1900, UMTS, and LTE2300/2500 bands. By the method of differential feeding, the coupling between the two radiation modes can be greatly reduced, which can provide a low envelope correlation coefficient (≤30 dB) and a high isolation (>30 dB) between different ports. A prototype of the antenna with dimensions 60 × 60 × 20 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> is fabricated, and the measured results are in great agreement with the simulated ones.

A Study of Impedance Switched Folded Monopole Antenna with Robustness to Metal for Installation on Metal Walls

A Study of Impedance Switched Folded Monopole Antenna with Robustness to Metal for Installation on Metal Walls

Bandwidth and directivity enhancement of an internal folded monopole antenna loaded by interdigital capacitor for ultra‐high‐definition television applications

AbstractAn internal antenna with bandwidth and directivity enhancement was developed for operation in ultra‐high‐frequency bands (UHF: 470‐771 MHz, bandwidth: 48.5%) for ultra‐high‐definition television (UHD‐TV) applications. The antenna is integrated into a 49‐in. TV model, which is surrounded by a bezel frame made of polycarbonate‐acrylonitrile butadiene styrene (PC‐ABS) plastic. This material was also used as a substrate in fabricating the antenna. The antenna has a compact size of 0.387λL × 0.023λL × 0.0093λL (where λL is the wavelength at the lowest operating frequency) and is fed by a 50 Ω coplanar waveguide (CPW) feedline. To achieve wideband operation and directional radiation, the proposed internal antenna was designed on the basis of a folded monopole antenna loaded with parasitic strips and an interdigital capacitor. The experimental results showed that the antenna exhibits a wide impedance bandwidth of 86% (400‐1000 MHz) under the criterion |S11| ≤ −6 dB (Voltage Standing Wave Ratio (VSWR) ≤ 3), a directional radiation pattern with a maximum realized gain of 5.2 dBi, and a radiation efficiency of more than 68%. These findings indicate that the antenna is suitable for UHD‐TV applications.

A Dual-Band MIMO Antenna With Enhanced Isolation for 5G Smartphone Applications

In this paper, a compact dual-band MIMO antenna array for 5G smartphone applications is proposed. The MIMO antenna consists of eight folded monopole antennas operating at 3.45-GHz band (3300~3600MHz). And the antenna elements with a size of $6.8\times 6.6\times4$ mm3 (about $0.078\lambda \times 0.075\lambda \times 0.046\lambda $ at 3.45 GHz), are disposed along each edge of the system circuit board. By introducing the decoupling structures, the isolation between inner antenna elements is improved from 10dB to 15.1dB in 3.45-GHz band (3300~3600MHz). Meanwhile the inner antenna units can generate an additional operating band covering 2400~2700MHz due to the coupling effect between the antenna elements and the proposed decoupling structures, which is promising for solving the problem of terminal space shortage. To verify the design principle of the proposed MIMO antenna array, the antenna is fabricated and measured. The measured results of efficiency and ECC are analyzed as well to demonstrate the performance of the proposed MIMO array. Channel capacity, user proximity and SAR analysis and are also given in this paper.

Folded monopole antenna with CSRRS for tri-band applications

In this paper, a miniaturize folded monopole antenna with complementary split ring resonator (CSRR) is proposed for tri-band applications. In the design procedure of the antenna, first a single band monopole antenna is designed for 2.88 GHz. For design a single band to dual band, the both arms of the radiating element (i.e. Monopole) is folded then it is resonated at 2.68GHz and 5.15GHz resonance frequencies, the resonance of the lower frequency is based on length of the monopole and higher order resonance is excited due to its folding effect. In order to extend its resonances for tri-band operation, the two identical size CSRRs (one on the left and another on the right from the feed line) are placed on the ground plane of the edge of the folded monopole, thus the entire structure is resonated at 2.47 GHz, 3.46GHz and 4.36 GHz frequencies. A simplified equivalent circuit model is developed for understanding its electrical behavior. Therefore, the proposed antenna has been suitable for WLAN, WiMAX and C-band applica- tions.

Usage of Characteristic Modes With Specific Boundary Conditions for Wideband Antenna Design: Application to a Cage Loaded Monopole Antenna

In this paper, a technique to design a compact wideband antenna with the optimization of the input impedance is proposed. This technique is based on the use of two sets of characteristic modes. The first one is associated with an open circuit at the antenna input port while the second is associated with a short circuit at the antenna input port. The link of this analyze with a classical modal approach by a rational fraction approximation of the input impedance is demonstrated. This technique is first applied to a basic folded monopole antenna, then to a disc-loaded folded monopole antenna in the aim to optimize its bandwidth and radiation pattern while reducing its size. The disc-loaded folded monopole antenna is modeled and measured. Its voltage standing wave ratio performances are equivalent to those of the Goubau antenna for equivalent dimensions. The radiation pattern is monopolelike on the full bandwidth.

CSRR based folded monopole tri-band antenna array and its system level evaluation

In this article, a folded monopole antenna loaded with complementary split ring resonators (CSRRs) is proposed for tri-band applications. The two bands of the antenna are generated by the folding of the monopole (first band is caused due to fundamental mode and another due to higher order mode) and CSRRs have been responsible for the third band. By using four such antennas in form of an array, the gain and bandwidth have been improved. The prototype of the antenna array is developed on FR4 substrate and simulated results are experimentally validated. A simplified equivalent circuit model of the antenna has been developed and analyzed to quantify the power loss due to input impedance mismatch at each resonance frequency. By using the EM model of the proposed antenna in the Keysight ADS verification test bench its suitability to operate in the system environment has been confirmed.

Equivalent circuit model for top-loaded folded monopole of extremely low profile

In this article, a concise equivalent circuit model for top-loaded folded monopole antenna (TLFMA) of low profile is presented. The TLFMA has one driven post and one shorting post, loaded with a circular conducting plate on the top, which can achieve a very low profile with a good radiation resistance. The equivalent circuit consists of two models, which are transmission-line mode and antenna mode. The impedance of TLFMMA can be easily get from this equivalent circuit model. The accuracy of the presented equivalent circuit model has been verified by the simulation and measurement results.

Hexa band mimo antenna with neutralization line for LTE mobile device application

ABSTRACTA hexa band MIMO antenna configured by two identical folded monopole antennas is proposed. The folded monopole antennas are connected by neutralization line. This antenna covers LTE 700, GSM 1800, GSM 1900, LTE 2300, LTE 2500 and 2.4 GHz WLAN applications. Good isolation characteristics and low envelope correlation coefficient is obtained. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1198–1204, 2016

무선 DVI 동글장치를 위한 스파이럴 구조를 갖는 폴디드 모노폴 안테나에 관한 연구

In this paper, we proposes a internal antenna for wireless DVI dongle device using the folded monopole structure. The proposed antenna uses a basic structure of spiral and monopole. The antenna optimized for parameters length, gap, width, and rectangle of folded monopole antenna using the spiral structure. To confirm the characteristics of the antenna parameters, HFSS from ANSYS Inc. was used for the analysis. We used an FR4 dielectric substrate with a dielectric constant of 4.4. The DVI dongle size of the proposed antenna is , and the size of the antenna area is . There is a value of return loss less then -10dB in 2.4GHz and 5.8GHz, band and the maximum antenna gain is -4.13dBi. The utilization possibility of the wireless DVI Dongle antenna have a folded monopole with spiral shape could be confirmed according to compare and analyze the simulation and measurement data.

Compact dual‐band antenna for 2.4/5.2/5.8 GHz WLAN service for laptop computer applications

ABSTRACTIn this study, a compact dual‐band antenna for wireless universal serial bus dongle applications is proposed. The proposed structure consists of a conventional folded monopole antenna (driven element) and a strip pattern that extends from the ground (GND) plane (shorten parasitic element). The proposed antenna exhibits triple‐resonance (f1, f2, and f3). The first two resonance frequencies (f1 and f2) are generated by adding the shorted parasitic element. The third resonance frequency (f3) is generated by the folded monopole antenna. The first resonance frequency (f1) covers 2.4‐GHz wireless local area network (WLAN) service, whereas the second and third resonance frequencies (f2 and f3) cover 5.2/5.8‐GHz WLAN service. Thus, dual‐band operation for 2.4/5.2/5.8‐GHz WLAN service can be easily performed. The antenna occupies a small area of 7 × 20 mm2. It can be easily connected to the edge of the system GND plane or the supporting metal frame of a laptop computer. Details of the proposed antenna are presented and studied. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2207–2213, 2015

A Multilayered Metamaterial-Inspired Miniaturized Dynamically Tunable Antenna

A multilayered metamaterial-inspired antenna with a pixel grid loading structure is introduced. The antenna consists of two patterned metal layers separated by a thin dielectric film. The first layer contains a folded monopole antenna surrounded by a metal pixel-based loading structure, whereas the second layer consists of a photoconductive pixel grid utilized to tune the antenna. Appropriate pixel configurations to produce a desired performance are implemented in simulation using a binary genetic algorithm (GA) and a MATLAB-HFSS (high-frequency simulation software) interface. HFSS simulations show that the antenna can be tuned over a wide frequency range by appropriate choice of pixel states on the second layer, using a variety of conductivities. As a proof of concept, the pixel grid on the second layer is initially made of a metal conductor. Multiple antenna configurations corresponding to a wide frequency range are constructed using a multilayer fabrication method. The measured reflection coefficients and radiation patterns are shown to be in good agreement with HFSS simulations, successfully demonstrating the ability to tune the antenna using the pixel grid on the second layer.

Miniaturized Dual-Band CPW-Fed Antennas Loaded With U-Shaped Metamaterials

New dual band miniaturized planar antennas loaded with 4-cell metamaterial is presented. The structure of the antenna consists of a coplanar waveguide at input, microstrip line, patch, metamaterial loaded substrate under patch, and back conductor. For simpler construction procedure, U-shaped and inverted U-shaped metamaterial loaded substrate under the patch is made in two layers. At the first band, these antennas work as a wideband monopole antenna with about 35% miniaturization compared to the folded monopole antenna, and at the second band as a wideband patch antenna with about 77% miniaturization compared to the conventional patch antenna.

Low‐profile inverted‐L aircraft antenna with one folding using ground edge current

A low-profile inverted-L antenna with one folding at 20−90 MHz bands for aircraft applications is presented. The designed antenna is installed on the top of the vertical stabiliser of an aircraft to increase the gain at 20 MHz using the ground edge current and to reduce air drag. The gain of the designed antenna is increased by 3 dB at 20 MHz, and the antenna length is reduced by 41% compared with the reference antenna, which is a folded monopole antenna coupled with a parasitic element. The measured 3 dB return loss bandwidth is 342.9 MHz (51.5%) and the peak gain at 200 MHz is −11.5 dBi for the 1/10 scaled sub-model. In addition, the omnidirectional radiation pattern was observed in the operating frequency.