Stable Omnidirectional Radiation Pattern Research Articles

Wideband rectangular dielectric resonator antenna for low‐profile applications

A new wideband low-profile omni-directional dielectric resonator antenna (DRA) is presented. By joining back-to-back two thin identical rectangular high-permittivity dielectric resonators (DRs) and feeding the arrangement with a microstrip feed line inserted in-between the DRs, an impedance bandwidth covering the frequency range from 4.78 to 12.32 GHz, or ~88.2%, is achieved. Importantly, the measured results show that the proposed low-profile DRA also provides a stable omni-directional radiation pattern with low cross-polarisation. The proposed antenna size is 12 × 24 × 2 mm 3 or ~0.191 λ 0 × 0.384 λ 0 × 0.032 λ 0 at 4.8 GHz.

CPW-Fed UWB antenna with sharp and high rejection multiple notched bands using stub loaded meander line resonator

This paper presents a CPW-fed UWB filter-antenna with sharp and high rejection multiple band notches for band-notched UWB communication applications. The band notch operation is achieved by employing a sharp bandstop filter (BSF) with multiple reject bands using only one element meander line resonator at the bottom layer through theoretical calculations and parametric studies. The adjustment of the notched bands is successfully accomplished by loading the meander line with open ended stubs to modify the harmonic frequencies to the desired bands. The structure of the proposed BSF is simple and compact so that the proposed filter-antenna is achieved with the same size of the reference UWB antenna without an extra area. Measurement results show that the proposed filter-antenna has two notches at the WiMAX systems operating in the 5.8GHz (5.725–5.85GHz) and at the international telecommunication union (ITU) operating in the 8.2GHz (8.025–8.4GHz). Also, it has sharp rejection characteristics at the edges of the federal communication commission (FCC) band for UWB communications. The experimental measurements are in good agreement with theoretical and simulation results for the BSF and the filter-antenna. Moreover, the filter-antenna exhibits stable omnidirectional radiation patterns except at the notched bands.

A Broadband Stepped Monopole Antenna with Loop Ground

In this paper, a broadband monopole antenna for next generation wireless communications is proposed. The proposed antenna consists of rectangular loop ground and a stepped monopole radiator. By employing a simple two-step monopole radiator, a third resonance is introduced, thereby achieving broadband characteristics. The antenna is printed on FR4 substrate and has a compact overall dimension of (50 mm × 63 mm × 1.6 mm). At |S11| < −10 dB, the simulated and measured impedance bandwidth of the proposed antenna is 93.2% (1.61–4.425 GHz) and 95.2% (1.69–4.762 GHz), respectively. The proposed antenna covers most of the LTE bands in the frequency range from 1.7 to 2.7 GHz and newer LTE bands in the range from 3.4 to 3.8 GHz. Also, the antenna exhibits stable omnidirectional radiation pattern and has gain varying from 3.2 to 4.8 dBi. Furthermore, the lumped element equivalent circuit model is presented and it validates three resonant modes of the proposed antenna.

Design of a Wideband Antenna With Stable Omnidirectional Radiation Pattern Using the Theory of Characteristic Modes

In this communication, the design procedure of a wideband antenna with omnidirectional radiation pattern is demonstrated based on the theory of characteristic modes. Consisting of a dipole and a loop antenna, the antenna has a very simple structure. A wide impedance bandwidth is obtained because of the simultaneous excitation of the antenna’s first two modes. Meanwhile, due to the fact that these two modes share a similar omnidirectional radiation pattern, a stable radiation pattern is also achieved across the operating frequency band. In order to identify the antenna’s different modes, a characteristic mode analysis of the antenna is carried out first. Then, a feed configuration is specifically designed to excite the desired modes. To validate the antenna design, a prototype was fabricated and tested. Measured results agree well with the simulated ones. Measurement shows that a wide impedance bandwidth of 44.2% with $\vert {\text{S}_{11}}\vert dB (1.85–2.9 GHz) and stable radiation patterns at both E-plane and H-plane were achieved over the operating frequency band.

Main Effects Ensured by Symmetric Circular Slots Etched on the Radiating Patch of a Compact Monopole Antenna on the Impedance Bandwidth and Radiation Patterns

Three compact monopole ultrawideband (UWB) antennas with half-wavelength symmetric circular slots etched on the radiating patch and operating in the UWB spectrum are proposed. Parametric studies followed by experimental results of the return loss coefficient S11 versus the circular slot length prove dual ensured functions. In fact, a switching from an impedance mismatch to an impedance matching appears when we replace a semicircular etched slot by a small circular slot while maintaining its inner radius constant. Simulated and measured reflection coefficient S11 of a fabricated prototype with a stack of two small circular slots concord well and prove an impedance bandwidth enhancement that covers 3.9–14 GHz frequencies band (S11 < −10 dB) compared to the impedance bandwidth 3.55–4.77 and 7.65–11.08 GHz (S11 < −10 dB) of the baseline antenna without slots. In addition, measured radiation patterns in the H-plane of the monopole with two etched symmetric slots, are stably omnidirectional at 5.8 and 7.5 GHz. It is noted that due to some strong transverse currents around the small circular symmetric embedded slots, the cross-polarization in the same plane and at the same frequencies are not as low as single monopole. We noticed that there appears to be a close correspondence between the minimum of EФ and the maximum of Eθ electrical components. That is to say, the signals of the co-polarizations are irrelevant to those of the cross-polarizations. Due to its impedance matching and its stable omnidirectional radiation patterns, reliability and the reduced occupation volume, the proposed printed monopole with two etched small symmetric circular slots is suitable for the emerging applications of the wireless technology.

Dual-Band Monopole Antenna Using Substrate-Integrated Suspended Line Technology for WLAN Application

In this letter, a substrate-integrated suspended line high-efficiency monopole antenna designed for 2.4/5.2 GHz wireless local area network (WLAN) application is proposed. The proposed antenna is composed of five stacked substrate layers with two embedded air cavities. Compared with the conventional monopole antennas, more metal surfaces of the proposed antenna can be used for radiation and impedance matching, which provides more flexibility for multiband antenna design. By utilizing the embedded air cavities, the loss of the whole structure is significantly decreased, thus efficiency of higher than 95% is achieved. Moreover, the stable omnidirectional radiation patterns are obtained in the two operating frequency bands of 2.25–2.90 and 4.95–5.94 GHz, which cover corresponding WLAN operation frequency bands.

Antenna for Ultrawideband Channel Sounding

A novel compact antenna for ultrawideband channel sounding is presented. The antenna is composed of a symmetrical biconical antenna modified by adding a cylinder and a ring to each cone. A feeding coaxial cable is employed during the simulations in order to evaluate and reduce its impact on the antenna performance. The optimized antenna demonstrates S $_{11}$ below $-$ 10 dB and a stable omnidirectional radiation pattern robust against the cable effect over the frequency band 1.5–41 GHz despite its compactness (the maximum electrical dimension is of 0.29 $\lambda _{\rm max}$ , where $\lambda _{\rm max}$ is the free-space wavelength at the lowest frequency of operation). A prototype of the antenna is fabricated and tested. The simulated and measured S $_{11}$ are in a good agreement. Measured radiation patterns confirm the pattern stability in terms of the direction of maximum radiation and 3-dB beamwidth.

Design of a patch antenna for ultra wide band applications

ABSTRACTA new monopole microstrip patch antenna design for ultra‐wideband applications are proposed in this paper. The proposed antenna is comprised of a ring‐shaped with additional slot and upper cutting edge, a 50‐ohm microstrip line‐fed and a slotted limited ground plane. The proposed antenna size is 3.5 cm × 2.4 cm × 0.16 cm and is energized by microstrip feed line. The finite‐difference time‐domain method based Computer Simulation Technology (CST) and finite element method based High Frequency Structural Simulator (HFSS) is adopted in this investigation. The proposed antenna has been achieved excellent gain and the calculated bandwidth of the monopole antenna cover whole UWB frequency range. However, the measured results demonstrate that stable omnidirectional radiation pattern within the entire frequency band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2152–2156, 2016

A high performance UWB antenna design for microwave imaging system

ABSTRACTIn this paper, a new design of ultra‐wideband (UWB) antenna is reported for a microwave imaging system aimed to cover the UWB bandwidth from 3.1 to 10.6 GHz. The structure has a very simple Hibiscus petal pattern patch with tapered microstrip fed a line and partial trapezoid ground plane. The gap between the Hibiscus petal pattern patch and partial ground of the antenna are optimized to achieve wide impedance bandwidth. Results show that the antenna has a fractional bandwidth of about 120% from 3.04 to 11 GHz with S11 &lt; −10 dB with stable omnidirectional radiation pattern. The average gain of proposed prototype is 5.1 dBi and the radiation efficiency is about 85% on an average over the bandwidth. The fidelity factor for face to face is 0.8469 and for side by side is 0.9232 which represent the lower distortion of signal. The characteristics of proposed antenna are successfully simulated, prototyped and measured. Fairly good agreements between the simulations and measurements have been achieved. The reported antenna has a better impedance match and mutual coupling that provides a practical approach to realize the antenna for the UWB microwave imaging system. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1824–1831, 2016

A Very Compact and Low Profile UWB Planar Antenna with WLAN Band Rejection.

A low-cost coplanar waveguide fed compact ultrawideband (UWB) antenna with band rejection characteristics for wireless local area network (WLAN) is proposed. The notch band characteristic is achieved by etching half wavelength C-shaped annular ring slot in the radiating patch. By properly choosing the radius and position of the slot, the notch band can be adjusted and controlled. With an overall size of 18.7 mm × 17.6 mm, the antenna turns out to be one of the smallest UWB antennas with band-notched characteristics. It has a wide fractional bandwidth of 130% (2.9–13.7 GHz) with VSWR < 2 and rejecting IEEE 802.11a and HIPERLAN/2 frequency band of 5.1–5.9 GHz. Stable omnidirectional radiation patterns in the H plane with an average gain of 4.4 dBi are obtained. The band-notch mechanism of the proposed antenna is examined by HFSS simulator. A good agreement is found between measured and simulated results indicating that the proposed antenna is well suited for integration into portable devices for UWB applications.

Bird Face Microstrip Printed Monopole Antenna Design for Ultra Wide Band Applications

AbstractIn this paper, a novel bird face microstrip printed monopole ultra-wideband (UWB) antenna is investigated. The proposed compact antenna consists of a ring-shaped with additional slot and slotted ground plane on FR4 material. The overall electrical dimension of the proposed antenna is 0.25 λ×0.36 λ×0.016 λ and is energized by microstrip feed line. The Computer Simulation Technology (CST) and the High Frequency Structural Simulator (HFSS) is applied in this analysis. The impedance bandwidth of the monopole antenna cover 3.1–12.3 GHz (9.2 GHz, BW) frequency range. The messurement displayed that the designed antenna achieved excellent gain and stable omnidirectional radiation patterns within the UWB. The maximum gain of 6.8 dBi and omnidirectional radiation pattern makes the proposed antenna that is suitable for UWB systems.

DESIGN OF CIRCULARLY POLARIZED PLANAR MAGNETO-ELECTRIC DIPOLE ANTENNA

A new design of a circularly polarized planar magneto-electric dipole antenna is proposed and presented. This antenna consists of dual horizontal T-shaped electric dipole and an inverted U- shaped feed line. The antenna possesses 21.1% impedance bandwidth, from 8.9 GHz-11.0 GHz, provides 3-dB axial ratio bandwidth of 9.52% ranging 10.0 GHz-11.0 GHz, exhibits stable omnidirectional radiation pattern with almost equal E-plane and H-plane radiation patterns and provides a peak gain of 6.2 dBi. Due to its good electrical characteristics and radiation parameters, the antenna is suitable for satellite and RADAR communication in X-band.

A small CPW‐fed UWB antenna with dual band‐notched charectrestics using two stepped impedance resonators

ABSTRACTIn this article, we propose a compact cpw‐fed ultra‐wideband (UWB) antenna with dual band‐notched characteristics. The dual band‐notched are achieved by using two stepped impedance resonators. The measured results show that the proposed antenna has an impedance bandwidth from 2.97 to 10.7 GHz (113%), defined by VSWR&lt;2, with two notched bands, covering all the WiMAX (3.3–3.6 GHz), WLAN (5.2–5.8 GHz), the antenna has a small size (20 × 20 × 1.6 mm3), and almost stable omnidirectional radiation pattern. The proposed antenna is designed, simulated, fabricated, and tested, and the measured results are in good agreement with the simulations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:464–467, 2016

Design and compare of Two Coplanar Fed Ultra Wideband Antenna

this paper, design and analysis of two compact coplanar waveguide (CPW) fed ultra wideband (UWB) slot antenna is presented. The proposed antenna consists of a rectangular slot on a ground plane and a triangular patch and another semi- circular patch at the interior portion of the feed that acts as tuning stub of the antenna. The return loss of the developed antenna are measured and compared, which shows that measured result is in good agreement with simulation. It is also seen that the proposed antenna has relatively stable Omni directional radiation pattern in the H plane and bidirectional radiation pattern in the E plane over the frequency range of 3.91 GHz to 10.6 GHz. Keywordsot Antenna, Coplanar Waveguide, Return Loss, Ultra Wideband

A semicircular shaped super wideband patch antenna with high bandwidth dimension ratio

ABSTRACTIn this article, a novel semicircular shaped mono pole antenna has been investigated for super wideband (SWB) applications with high bandwidth dimension ratio (BDR). The proposed antenna consists of semicircular shape patches and partial trapezoid ground plane. A tapered feed line is precisely connected to semicircle shaped patch, which provides extremely wide impedance bandwidth greater than ultra‐wideband (UWB). The gap between the trapezoid ground plane and semicircular patch also plays a vital role to achieve wide impedance bandwidth. Studies of the antenna are performed using computer simulation tool HFSS. Prototype of the antenna is used for validation and verification for simulation results. Measurements to determine that the proposed printed antenna has an extremely wide impedance bandwidth (VSWR 2:1) from 1.30 to 20 GHz (175.58%) with a ratio bandwidth of 15.38:1 and BDR of 4261. 007 which is the highest among literature review. Furthermore, the proposed antenna also demonstrated a wide 14‐dB bandwidth from 4.90 to 10.95 GHz, which is suitable for UWB outdoor propagation. The simple construction, much impedance bandwidth, average peak gain (4.18 dBi), and stable omnidirectional radiation pattern are a good deal sounder than the recently reported SWB antennas which make it appropriate for many wireless communication systems such as L band, WCDMA, ISM, Wi‐Fi, LTE 2600, Bluetooth, WLAN, WiMAX, UWB, and MVDDS. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:445–452, 2015

Circularly Polarized Conical-Beam Antenna With Wide Bandwidth and Low Profile

This work introduces a circularly polarized (CP) conical-beam antenna with low profile and wide impedance & axial ratio (AR) bandwidths. The antenna structure simply consists of a wideband monopolar patch antenna and eight parasitic loop stubs for generating vertically polarized electric field Eθ and horizontally polarized field Eφ, respectively. The proposed antenna is low profile but wideband because of merging the TM01 and TM02 modes at around the center frequency. In order to obtain the wideband CP radiation, the eight parasitic loop stubs are printed and placed sequentially along the radiating edge of the patch. With the resultant radiations from both the patch antenna and the loop stubs, the CP conical-beam radiation pattern can be obtained. In addition, a parametric study of the shorting vias effect, number of loop stub elements, and loop widths are demonstrated how to design this wideband CP antenna. The antenna exhibits the wide impedance bandwidth of 28% from 4.9 to 6.5 GHz (for the reflection coefficient ≤ -10 dB) and the 3-dB AR bandwidth of 14.4% from 5.8 to 6.7 GHz. The thickness of this antenna is only 0.06λ in terms of the free-space wavelength at its lowest operation frequency. Stable omni-directional conical-beam radiation patterns are observed over the operating bandwidth with the peak gain of 4.9 dBic. The antenna can cover the uplink of standard C band (5.85 to 6.425 GHz) for satellite communication.

Triple band notch UWB printed monopole antenna with enhanced bandwidth

In this paper, a compact triple band-notched ultra-wideband (UWB) printed monopole antenna is proposed with enhanced bandwidth. It exhibits a stable omnidirectional radiation pattern and a dipole-like pattern in the H-plane and E-plane, respectively, for the entire UWB. The antenna consists of a rectangular patch with two bevels. To realize notch characteristics in WiMax (3.3–3.7GHz) and WLAN (5.15–5.85GHz) band, two round shaped slots of half wavelength are inserted in radiating patch. The rectangular ground plane has two bevels in upper edge to enhance bandwidth which cover the frequency range from 3 to 15GHz. The two bevels also help in getting impedance matching especially beyond 10.6GHz. A pair of C-shaped slots is etched in ground plane to get a third notch in X-band satellite communication band (7.1–7.76GHz). The effects of each individual slot on band notch characteristics are also investigated. The proposed antenna exhibits stable gain throughout the UWB and it also has a very good capability to suppress gain at notched band. Moreover, the designed antenna has a compact size of 31mm×22mm.

Gain Enhancement of Uwb Mimo Antennas Using A High Isolation Technique

Antenna diversity is an important technique for modern wireless communication systems. By employing multiple-antennas, effects such as multi-path, small-scale fading as well as co-channel interference, can be reduced. Furthermore, the system's capacity can be increased significantly by using multiple-antenna However, for compact devices, mutual coupling between antenna elements may become severe due to their small distance. In order to improve the isolation between array elements, several scenarios have been proposed. Two truncated square monopoles orthogonally and symmetrically printed on ground plane to improve the isolation. A slot is placed on the ground plane to reduce the mutual coupling between two radiators. Three stubs are introduced to achieve spatial diversity.In this project, a novel diversity antenna for UWB applications is proposed. Two square shaped monopoles are employed to achieve wideband performance. The 10dB return loss bandwidth of the antenna ranges from3.1GHz to 10.6GHz. In order to improve the isolations between the two radiators, a T stub is employed. The antenna design is accomplished by using EM simulator IE3D. As reported, the isolation between the two ports is higher than 39dB within 3.3GHz to 10.4GHz, stable omnidirectional radiation patterns with gain flatness of about 3dBi over the entire frequency rangearealsoobtained

Coplanar Waveguide Fed Compact Wide Circular-Slotted Antenna for Wi-Fi/WiMAX Applications

A coplanar waveguide (CPW) fed printing and wide circular slotted, dual band antenna for Wi-Fi/WiMAX applications are presented. The antenna mainly encompasses a ground with a wide circular slot in the centre, a rectangular feeding strip, and two pairs of symmetric planar invertedL(SPIL) strips connecting with the slotted ground. The tuning effects of the rectangular patch, ground size, and SPIL strips to the resonance and matching condition are examined by HFSS and the prototype is fabricated and measured. The simulation and experimental results show that the antenna has an impedance bandwidth with −10 dB reflection coefficients 600 MHz (3.26–3.86 GHz, lower band) and 1040 MHz (5.02–6.26 GHz, upper band), which can cover both the Wi-Fi 5.2/5.5/5.8 GHz and WiMAX 3.3/3.5/3.7/5.8 GHz bands. Moreover, a stable omnidirectional radiation pattern and average peak gain for lower band 3.23 dB and upper band 5.93 dB have been achieved, respectively.

A Slotted Circular Monopole Antenna for Wireless Applications

In this paper, a compact slotted circular monopole antenna with spike shaped slots embedded in it is presented. Also, the proposed antenna has ground length limited to 33% of substrate length. This ground is provided on the back side of the antenna geometry to excite the antenna by microstrip line feed. A slotted circular patch element will be achieved by subtracting 45 degrees rotated square patch of 12mm x 12mm, and then by proper scaling. In this study the geometry is scaled separately by 60%, 40%, 20%, and finally the resultant is obtained by uniting them. This final geometry offers an ultra wide band operation. The overall size of the antenna is 30mm×32.4mm×1.6mm including finite ground feeding mechanism. The antenna operates in the frequency range from 2.5-15GHz covering FCC defined UWB band with more than 130% impedance bandwidth. Stable omni-directional radiation patterns in the desired frequency band have been obtained. Measured data fairly agree with the simulated results.