Small Monopole Antenna Research Articles

Design of Compact and Superdirective Metamaterial-Inspired Two- and Three-Elements Antenna Arrays

This paper presents the development of a miniature antenna array in a small space in order to achieve superdirectivity for long-range communication. The proposed structures consist of a superdirective metamaterial-inspired array based on a capacitively loaded loop (CLL) driven by an electrically small monopole antenna. This elementary antenna is then used in two- and three-array configurations separated by a fixed interelement distance of 0.1λ to achieve a higher directivity and compact size (with λ the wavelength calculated at the operation frequency 1.850 GHz). The design of the elementary antenna, its simulated radiation performances, as well as those of the parasitic array are also reported. The results of the optimization of two- and three-antenna arrays are discussed. For this study, three corresponding prototypes were fabricated and tested. The measured impedance mismatch and radiation pattern results are presented and shown to be in good agreement with their simulated values. The maximum measured directivity is equal to 5.9 dBi and 4.75 dBi in the case of the two- and three- elements, respectively. The proposed antenna arrays can serve for the realization of point-to-point wireless links and can have a significant impact on compact and high-directive radiofrequency front-ends of a wireless system and for wireless power transfer applications.

The Small UWB Monopole Antenna with Stable Omnidirectional Radiation Pattern

Ultra Wideband (UWB) technology is an unmodulated wireless digital communication system that uses an extremely short duration pulse to transmit information bit. Because of this pulse, the UWB system needs a very wide bandwidth. Federal Communication Commission (FCC) has regulated the 3.1 – 10.6 GHz frequency spectrum for UWB. Since FCC released this frequency, many research in telecommunication have been done on UWB systems. One of them is a development of an Antenna that is suitable for UWB devices. UWB antenna characteristics require FCC band, omnidirectional radiation pattern, and compact size. In order to meet these needs, an antenna with a simple structure in the form of a monopole patch antenna with a similar patch size and ground width has been designed. The antenna is built on an FR4 – epoxy substrate material, with 4.4 dielectric constant and 1.6 mm thickness. The antenna feeding structure consists of two 100 Ω and 50 Ω lines with a wideband impedance matching scheme using tapered side and tapered transformers. The antenna design and optimization processes are conducted using electromagnetic simulation software, and measurements are carried out in an anechoic chamber. Simulation and measurement results show good agreement, and the antenna can work at frequencies 3.5 - 11.3 GHz with a gain of 1.5 – 3.25 dBi and stable omnidirectional radiation patterns. The antenna has dimensions of 27 × 8 × 1.6 mm, which are smaller than the antenna reported in the last research and suitable to be applied on various UWB devices.

Small Size Wideband Monopole Antenna with Five Notch Bands for Different Wireless Applications

Small Size Wideband Monopole Antenna with Five Notch Bands for Different Wireless Applications

Transient analysis of dynamically switched frequency shift keyed transmitters

A dynamically switched matching network for transmitting a wideband frequency shift keyed (FSK) signal from an electrically small monopole antenna is studied. The effects of switch synchronization, frequency deviation, the antenna's impedance, and Q-factor at the two carrier frequencies are studied. It is found that the average energy per bit of the transmitted FSK waveform is maximum when the loss of reactive energy between states transition is minimised by switching it at the instant of peak voltage across the antenna's terminals. However, a switching network topology that stores more energy is shown to be less sensitive to the synchronization condition. In addition, we show that this dynamically switched system transmits more bit energy when the carriers are closely spaced due to a smaller change in stored energy levels between states. Results are presented using a detailed analytical study and full wave simulation. Near field measurements from a monopole antenna circuit model show that under proper conditions, an FSK signal can be transmitted at a rate 7 times greater than the bandwidth of the transmit antenna with minimal signal quality degradation.

Electrically Small Metamaterial Inspired Monopole Antenna Using Double Negative Metamaterial and Ring Resonators

This paper proposes a new metamaterial inspired electrically small multi-band monopole antenna. The proposed antenna can operate at DCS 1800 in the lower band and covers two wireless local area network (WLAN) bands in the higher band. This paper describes the design and a detailed analysis of the electrically small antenna, where the compactness is achieved by the application of double negative metamaterial on a monopole antenna and multiband operation is achieved by the addition of two ring resonators. The ground structure is modified for giving proper impedance matching at lower bands. Moreover, an additional double negative structure of similar design is also incorporated to enhance its gain. A comparative study of the proposed antenna with other reported electrically small antennas is summarized and analyzed. A prototype of the proposed antenna is fabricated on a low cost substrate and experimentally validated.

Small size monopole antenna with tri-band notch characteristics for broadband application

Abstract In this research article, the design of a broadband monopole antenna with triband notch characteristics is proposed. Notch characteristics are achieved by using an E-shaped slot on the patch and a U-shaped slot on the 50 Ω microstrip feed line. An E-shaped slot is introduced on the metal patch to reject one frequency band of 6.6 − 7.5 GHz and when an additional U-shaped slot is introduced on the microstrip feed line, it provides two-notch frequency bands of 4.8 − 5.7 GHz and 14.2 − 17.5 GHz. The notch bands are effectively used to avoid undesired interference from the WLAN, C band, and Ku band. The proposed antenna provides a very broad frequency range from 3.3 − 19.5 GHz except for three notch bands. The antenna is small in size and easy to design with only a volume of 29 mm × 21mm × 1.6 mm. The antenna is useful for broadband applications.

Soft, Bistable Actuators for Reconfigurable 3D Electronics.

Existing strategies for reconfigurable three-dimensional (3D) electronics are greatly constrained by either the complicated driven mechanisms or harsh demands for conductive materials. Developing a simple and robust strategy for 3D electronics reconstruction and function extension remains a challenge. Here, we propose a solvent-driven bistable actuator, which acts as a substrate to reconstruct the combined 3D electronic device. Extraction of silicon oil from a hybrid poly(dimethylsiloxane) (PDMS) circle sheet buckles the dish to a bistable structure. The ultraviolet (UV)/ozone treatment on one surface of the PDMS structure introduces an oxidized layer, yielding a bilayered, solvent-driven bistable smart actuator. The snap-back stimulus to the oxidized layer differs from the snap-through stimulus. Experimental and numerical studies reveal the fundamental regulations for buckling configurations and the bistable behavior of the actuator. The prepared bistable actuator drives the bonded kirigami polyimide (PI) sheets to diverse 3D structures from the original bending configuration, reversibly. A frequency-reconfigurable electrically small monopole antenna is presented as a demonstration, which paves a way for the applications of this actuator in the field of reconfigurable 3D electronics.

Rectenna Integrated With Small Square Monopole Antenna with Inverted T-Shaped Notch for ISM Band Applications and it’s Data in Networks

Rectenna Integrated With Small Square Monopole Antenna with Inverted T-Shaped Notch for ISM Band Applications and it’s Data in Networks

A Coalesced Kite Shaped Monopole Antenna for UWB Technology

A small and compact monopole antenna of dimensions 25 × 18 × 1.6 mm3 is presented for UWB communications. The proposed design consists of two kite shaped radiators in coalesced form and a tapered slotted ground plane for the UWB characteristics. The parametric study of the patch and the modified ground plane is made and the measured impedance bandwidth of 14.2 GHz (2.8–17 GHz) is achieved. The measured antenna gain varies from 2.28 to 5.0 dBi for the entire frequency band of application. Group delay, signal analysis and antenna isolation |S21| are also studied at different orientations of the antenna and found to be quite satisfactory to meet the requirements for UWB applications. The co- and cross-polarization patterns are also calculated for E and H-planes, and compared with the measured results. Antenna simulation and optimization are performed using CST Microwave Studio and design is fabricated and measured for the validation of the results.

A Compact Integrated Small Disk Monopole Antenna with DGS for Wireless Applications

The structure of a compact Micro strip feed circular monopole antenna working in the frequency range of (2.5GHz-4GHz) and wideband of frequency ranging from 4.9GHz to 19.93GHz is proposed in this paper. Using a circular radiating monopole with terrible ground wideband frequency operation is possible. Two frequency bands can be accomplished by separating the middle part of the patch and further engraving a circular arc r=4.4 and a loss tangent of 0.02 was utilized to realize and simulate this antenna. It can be operated in both the frequency bands 2.5-4GHz and 4.9-19.93GHz [wideband] possessing less than -10dB reflection coefficient. The whole WB and also in the low-frequency band as mentioned above shows a sturdy radiation pattern.

Extremely electrically small MF/HF antenna

This study presents an extremely small frequency-tunable monopole antenna operating at medium frequency/high frequency (MF/HF) band with an omnidirectional radiation pattern. Most of the existing miniaturisation techniques operate at low bandwidth as well as low efficiency. The design is based on a capacitive top, allowing the antenna to resonate at much lower frequencies, and a tunable inductive centre loaded. Utilising the capacitive top, the radiation resistance of the antenna is significantly increased. The resonant frequency can be tuned over a wide range of frequency (0.974–30 MHz) without changing the antenna total size by virtue of the tunable loading coil. The tuning system contains arms, motors, contactor, microcontroller and remote control. The experimental results are 0.0032 λ, ka = 0.01, |S11| = − 15.8 dB, gain = −13.9 dBi and ɳ = 2.2% at its lowest resonant frequency.

Design and fabrication of small and low profile microstrip monopole antenna using CRLH-TL structures

ABSTRACTThis paper presents compact and low profile microstrip monopole antenna using composite right/left-handed transmission line (CRLH-TL) structures, which has multiband performance. The physical size of the antenna is 30 mm×30 mm×1.6 mm. The antenna is simulated utilizing the CST CAD tool, and the circuit model of the antenna is designed using ADS software. The simulated reflection coefficient of ADS is in good compromise with the CST. Also, the antenna is fabricated and the simulation and measurement results are in good agreement with each other. The proposed antenna with two unit cells has good reflection coefficient and quasi-omnidirectional patterns with the peak gain of 3.43 dBi at 8.37 GHz and the radiation efficiency of 70% at 2.4 GHz and 4.58 GHz. Also, the antenna with three unit cells has the peak gain of 5.2 dBi at 4.19 GHz and the efficiency of 85% at 3.04 GHz that covers WiMAX/WLAN/ITU bands.

Wideband, Non-Foster Impedance Matching of Electrically Small Transmitting Antennas

Electrically small antennas (ESAs) can be passively matched only over very narrow bandwidths and the resulting antennas have low gains. These are the major limiting factors for ESAs used in transmit applications, especially at high-frequency (HF) and lower Very HF frequency bands. This paper discusses the challenges of transmit ESA matching circuit design and the design process of a new non-Foster transmit matching architecture for electrically small monopole antennas that achieves wide bandwidth, high transmission efficiency (transducer power gain), and stability at the same time. The proposed circuit is composed of a current buffer (for high isolation), a transformer (for real-part matching), and a negative impedance converter (for imaginary-part matching). The measured −6 dB (−10 dB) $|S_{11}|$ fractional bandwidth of the proposed non-Foster transmitting system is 110% (39%), while the maximum bandwidth that can be achieved is 0.076% (0.047%) when matched with the conventional passive matching. The transmission efficiency of the system is improved by as much as 34.4 dB compared to the same antenna without the proposed non-Foster matching circuit, and it retains an enhanced efficiency over the entire frequency band of operation (26–89 MHz). The system remains stable within this frequency band. The measurement results of the compact and broadband transmitting antenna prototype verify the design concept.

Low-Profile Wide-Scan Closely Spaced Antenna Array of Electrically Small Antennas

ABSTRACTIn this paper, a wideband, wide-scan, low-profile antenna array of electrically small monopole antennas is proposed. The array is designed for L-band applications. An electrically small antenna with an in-built feed and matching network is proposed as an unit element of the phased array. The size of the unit cell is 0.15 λ × 0.21 λ × 0.07 λ where λ is free space wavelength at 1 GHz. The array is designed taking into account strong mutual coupling between the elements. For the case of the infinite array, an impedance bandwidth of 45.7% is observed along with wide angle scanning of −50° to 50°. To analyse the performance of the finite array with mutual coupling, a prototype of 4 × 4 element finite array has been simulated and fabricated. For the finite array, more than 80% efficiency is observed throughout the band of interest. The prototype of the proposed array is fabricated and tested. A significant match is observed in measured and simulated results.

A Small Quad-Band Monopole Antenna with Folded Strip Lines for WiMAX/WLAN and ITU Applications

In this article, a small Quad-Band microstrip patch antenna with folded strip lines for WiMAX/WLAN and ITU Applications is presented. This antenna consists of eight symmetrical rectangular folded strip lines with 2 PIN diodes, ground plane and dimensions of 15 -20 -1.6mm 3 . Using PIN diodes integrated within the antenna configuration, the antenna would be able to operate in two modes. The operational frequency bands of antenna are WLAN (2.4/5.2/5.8GHz), WiMAX (3.5/5.5GHz) and ITU-Region 1 allocation (4.3GHz) when diodes=on. In this design approach of antenna, omnidirectional radiation pattern and       S 11 -10dB bandwidths are obtained for all frequency bands. This antenna is fabricated on FR4 substrate with permittivity of 4.4 and loss tangent of 0.024.

Optimized Manipulation of the Network Characteristic Modes for Wideband Small Antenna Matching

Multiport antenna systems can be regarded as $N$ -port networks, which can be analyzed using the theory of network characteristic modes (NCMs). Due to the profound physical insights provided by an NCM, a desired antenna performance can be achieved by properly manipulating the modes through reactive loading at specified ports. This paper presents a new matching technique for an $N$ -port internally loaded small antenna. By combining the NCM with the differential evolution algorithm, optimal reactive load values can be calculated. These loads can manipulate the NCMs to match the antenna in a desired bandwidth. Unlike other matching techniques based on the NCM, the desired bandwidth is achieved through internal reactive loading without the need for an input matching network. Two examples of electrically small monopole antennas are studies. In both examples, we study the possibility to match the antennas in the GSM 900 band, and we further investigate the possibility to achieve wider bandwidths by varying the number of ports and the loading topologies based on the interpretation of the characteristic modes. The loaded antennas are wideband with a relatively stable radiation pattern and an efficiency higher than 90%. To confirm the theoretical results, a prototype is fabricated and measured.

A Small Dual Band-notched UWB Monopole Antenna

A small ultra-wideband antenna having two rejected bands is proposed. The antenna is simply composed of a micro strip-fed fork-shaped monopole, a pair of rectangular stubs which are shorted with the ground plane, a rectangular strip and an L-shaped strip connected with the ground plane. The antenna has compact dimension of 20 × 31 × 1.6 mm. The impedance matching with 10 dB return loss is from 3.1GHz to 10.6 GHz, in which there is two rejected bands which cover 3.3–3.68 GHz and 5.12–5.85 GHz.

A novel small triple-band monopole antenna with crinkle fractal-structure

A novel monopole antenna with crinkle fractal-structure for multiband applications is presented. In this paper adding crinkle fractal leads to increasing the number of resonance frequency. The operating frequencies of the proposed antenna are 1.780/3.520/5.260GHz. The prototype of the proposed antenna is fabricated on an inexpensive FR-4 substrate. The size of the proposed antenna is 14×14mm2 which has crinkle shape strip on top side. The radiation pattern of the proposed antenna is nearly omnidirectional. The simulated and the experimental results are in acceptable agreement with each other and confirm good performance for the offered antenna.

Mini UWB-Bluetooth Antenna Design with Band-Notched Characteristics

Objective: In this paper a novel small size antenna for Ultra Wide Band (UWB) and Bluetooth application is proposed which there by minimize the potential interference between the UWB system and WLAN system. Band notch are designed to reject 5.15-5.5825 GHz frequency band f Wireless Local Area Network (WLAN) application based on IEEE 802.11 standard. Methods/Statistical Analysis: This is achieved by choosing a small monopole antenna with U shaped radiator and a rectangular ground plane. A pair of L shaped slot is etched on the ground to obtain the WLAN band notched characteristics. Findings: The antenna consisting of fork shaped radiating element is fed to a 50 ohm micro strip line. Dimension of the central arm govern the Bluetooth band while the U shaped monopole antenna govern the Ultra Wide Band UWB. Furthermore by placing two L shaped slot on the ground plane. Adjusting the total length of the L shaped slots on the ground plane the desired band notched frequency can be controlled to minimize the potential interference in the system. The characteristics of the designed structure are achieved using finite element method based electromagnetic simulator, HFSS and the fabrication is done using FR4 substrate. Applications/Improvements: The dimensions are varied to get the desired radiation promising return loss data with good matching, high gain, good efficiency and reject bands. The experimental result shows that the proposed antenna is a good candidate for application in UWB communication systems.

Asymmetric Defected Ground Structured Monopole Antenna for Wideband Communication Systems

A compact wideband CPW-FED monopole antenna for wireless communication applications is presented in this paper. The proposed antenna consists of very compact in size on RT-Duroid substrate with thickness of 1.6mm. The initial design antenna structure generates two separate impedance bandwidths to cover the frequency band of several wireless communication applications. In addition, the antenna exhibits monopole like radiation characteristics and good antenna gain over its operating bands, which is suitable to be integrated within the portable devices for wireless communication. These monopole antennas require a relatively large ground-plane structure that can be of various configurations typically in the shape of a square, rectangle, circle, or ellipse. Defected ground structure (DGS) has also been investigated and found to reduce the antenna size as well as excite additional resonance modes. In this paper, a relatively small wideband monopole antenna is presented for Wireless communication applications. The antenna’s performance was simulated using Ansoft’s HFSS prior to its fabrication. The effect of the antenna’s key structural parameters on its performance also analyzed.