Symmetrical Radiation Patterns Research Articles

Ka대역 위성통신용 타원형 이중옵셋 그레고리안 안테나 설계

In this paper, we have designed the elliptical dual offset gregorian antenna which can use Ka band earth station antennas in the fixed-satellite service. The structure of antenna is increasing the antenna gain by decreasing blockage areas and decreasing wind effects by shortening height of the antenna. The corrugate horn antenna for this antenna has symmetric radiation patterns and low side lobe levels that can meet ITU-R envelope. The distribution of electric field on a aperture of main reflector is calculated by an ray-tracing method that use the radiation pattern of the feed horn. The final geometric of antena is decided by choosing the distribution that comply with antenna requirement. The FEKO analysed electrical performance of this antenna. The fabricated antenna has 45.0dBi(@30.0GHz)/41.7dBi(@20.2GHz), high efficiency and low side lobe level that meet ITU-R S. 580-6 envelope.

On the Matching of Microstrip-Fed Dielectric Resonator Antennas

As the permittivity of dielectric resonators decreases, it becomes difficult to feed the dielectric resonator antennas (DRAs) using direct microstrip lines. The variation of the resonant input resistance with the feed location becomes smaller, while the maximum achievable peak resistance dramatically drops to lower than 50 Ω in most cases. To satisfy the impedance matching, field matching, improve coupling to low-permittivity dielectric resonators, and further increase the antenna bandwidth associated with the dominant mode, without disturbing far-field properties, tapered microstrip line-fed DRAs are proposed, designed, fabricated and evaluated in this communication. Both measurements and simulation investigations are presented and the results are compared with other forms of microstrip feed lines. The impedance bandwidth can be 75% larger than the bandwidth achieved by the step-shape microstrip-fed DRA. Symmetrical radiation patterns with low cross-polarization levels (lower than -22 dB) and a gain ranging from 4.9 to 6.8 dBi, within the impedance bandwidth of the antenna, are observed in the measurements. It is also shown that the proximity coupled tapered microstrip line is an ideal feeding for high-permittivity DRAs in situations where the microstrip line cannot be positioned underneath the dielectric resonator. To verify, one such antenna is designed, simulated and experimentally investigated, obtaining satisfactory results.

Inhomogeneous Metasurfaces With Engineered Dispersion for Broadband Hybrid-Mode Horn Antennas

Metamaterial and metasurface structures, which satisfy the balanced hybrid conditions, have been recently proposed for designing hybrid-mode soft and hard horn antennas. In this paper, we present the design of broadband soft metasurfaces and their applications in hybrid-mode conical horns. These designs exhibit surface characteristics that can be controlled by adjusting the constituent structural elements. The analysis and design of metasurfaces were performed on both a planar platform and in a cylindrical waveguide structure. Such dispersion-engineered metasurfaces with customized surface properties can support the desired hybrid modes in a cylindrical waveguide, facilitating their usage in horn antennas. By engineering the metasurfaces with regard to their surface impedance as well as tailoring their spatial distributions along the wall of the horn, we demonstrate an inhomogeneous metahorn with superior performance and broader bandwidth compared to those with uniform liners. The symmetric far-field radiation patterns with low sidelobe and cross-polarization levels, together with the corresponding aperture field distributions, signifies the hybrid-mode operation of the horn, validating the efficacy and broadband performance of the metasurfaces. Such metasurface-lined horns can be employed as soft feeds in dual polarization antenna systems.

CPW‐Fed Printed Antenna Design with Multislit Patches for UWB Communications

ABSTRACTA novel compact coplanar waveguide‐fed printed antenna with three separate patches embedded by narrow slits is designed and analyzed for ultrawideband (UWB) communication applications, which can provide UWB, high gain, and multiresonant impedance characteristics simultaneously. The dimension of the proposed antenna is 50 × 50 × 0.3 mm3. The measured results agree well with the simulated prediction and show a broad bandwidth of 13 GHz ranging from 2.8 to 15.8 GHz with return loss less than −10dB. Furthermore, the proposed antenna gain ranges from 4.3 to 8.2dBi, which can achieve almost symmetrical radiation patterns. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3023–3025, 2013

A Compact Single-Feed Circularly Polarized Microstrip Antenna with Symmetric and Wide-Beamwidth Radiation Pattern

A compact single-feed circularly polarized microstrip antenna is proposed to achieve symmetric radiation pattern over a wide range of observation angles. In order to reduce the radiation aperture and consequently broaden the circular polarization (CP) and the half power beamwidth (HPBW) of the antenna, a partially etched superstrate and a conducting cavity are employed in the design. Further, reasonable axial ratio (AR) and impedance bandwidths are realized within the compact structure by using a simple series crossed-slot aperture coupled feeding. As a consequence, the overall dimension of the fabricated prototype is 0.32λ0× 0.32λ0× 0.12λ0at the center operating frequency of 1.56 GHz, and a 3.0% overlapped bandwidth of 10 dB return loss (RL) and 3 dB AR is obtained. Within the bandwidth, symmetric CP radiation pattern over almost the entire upper hemisphere is observed and the HPBW is also increased from 60° to 106°.

A BAND-NOTCHED UWB PRINTED ELLIPTICAL-RING MONOPOLE ANTENNA

In this paper, a compact ultra wideband (UWB) monopole antenna with a band-notched characteristic is presented. The band- notched characteristic is achieved by inserting a U-shaped slot in the half elliptical ring radiating patch. The measured bandwidth of the designed antenna for jS11j 6 i10dB spans 3.1GHz to 9.3GHz with a notched band (jS11j > i10dB) spanning 5.12GHz to 5.99GHz. A quasi-omnidirectional radiation pattern in the x-z plane and quasi- symmetrical radiation patterns in the x-y and y-z planes are obtained throughout the operating band. The antenna is suitable for UWB communication applications and also reduces the interference with wireless local area network (WLAN) systems. The parameters which afiect the performance of the antenna in terms of its frequency domain characteristics are investigated in this paper.

A Novel Miniaturized Broadband Dual-Polarized Dipole Antenna for Base Station

A novel dual-polarized dipole antenna for base-station applications is presented in this letter. The proposed antenna is composed of a cross dipole, a square loop, a square plate, and a small-size reflector. The square loop and the square plate act as a parasitic radiator and a director, respectively. By introducing the two parts, the impedance bandwidth of the cross dipole can be significantly enhanced, and broadside radiation patterns with narrow beam can be also obtained. Experimental results show that the proposed antenna can operate from 1.71 to 2.69 GHz with low VSWRs at the two ports. High isolation ( > 22 dB) and stable antenna gain (~ 8 dB) are also achieved over the entire operating frequency band. The antenna has symmetrical radiation patterns both in vertical and horizontal planes, and the half-power beamwidth is 70°±5°. Furthermore, the size of the proposed antenna is very compact, which is only 0.513 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.513 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.388 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at the center of the operating frequency band.

A Wideband Waveguide Antenna with Nearly Equal E- and H-Plane Radiation Patterns

A novel wideband waveguide antenna with excellent performance is proposed, which is composed of a coaxial-waveguide transition and an open-ended rectangular waveguide loaded with a pair of horizontal umbrella-shaped metallic brims. The brims perpendicular to two broad walls of the waveguide are constructed to modulate the antenna to radiate nearly identical E- and H-plane radiation patterns. A wideband impedance matching performance is achieved with a fractional bandwidth of 40% through the introduction of short-stepped ladders. The antenna has the advantages of simple structure, symmetric radiation pattern, low-cross polarization, moderate back lobe, and almost constant beamwidth.

Analytical model of amplitude-weighted array technology in forming symmetrical radiation patterns

A method on amplitude-weighted array technology is proposed based on an analytical formula in which the radiation amplitudes of array elements are evaluated analytically by a random symmetrical far-field radiation pattern. Using this formula, any desired spatial radiation pattern in the far field could be built by applying the analytical solutions of radiation amplitudes of array elements. To check the validity of this formula as well as the proposed technique, an annular intensity distribution as target far-field pattern is designed, and the respective radiation amplitude of array elements are determined by solving the formula analytically. The available far-field pattern is calculated by applying these solutions and then compared with the target far-field pattern. The theoretical results show the capabilities of the analytical derivation as well as the proposed technique in forming specific radiation patterns.

COMPACT PLANAR UWB ANTENNA WITH BAND NOTCH CHARACTERISTICS FOR WLAN AND DSRC

In this paper, a compact ultra-wideband microstrip-fed annular ring antenna with band notch characteristics for wireless local area network (WLAN) and dedicated short-range communication (DSRC) is proposed. The proposed antenna comprises an annular ring patch and a partial ground plane with a rectangular slot. The notched frequency band is achieved by etching a partial annular slot in the lower portion of the ring radiator. The centre frequency and bandwidth of the notched band can be controlled by adjusting the width and position of the annular slot. Measured results show that the proposed antenna achieved an impedance bandwidth of 3{10.6GHz with a notched frequency band centred at 5.5GHz. Compared to the recently reported band-notched UWB antennas, the proposed antenna has a simple conflguration to realize the band notch characteristics to mitigate the possible interference between UWB and existing WLAN & DSRC systems. Furthermore, a symmetric radiation patterns, satisfactory gain and good time domain behaviour except at the notched frequency band makes the proposed antenna a suitable candidate for practical UWB applications.

DESIGN OF A NOVEL WIDEBAND LOOP ANTENNA WITH PARASITIC RESONATORS

A novel coax-fed wideband loop antenna loaded with rectangular patches and U-shaped elements is presented and studied. By inserting a pair of rectangular patches inside the strip loops and employing a pair of U-shaped elements as the parasitic resonators, two additional resonances are excited and a good performance of bandwidth enhancement can be obtained. The measured results indicate that the impedance bandwidth (VSWR•2) is about 87.1% from 1.58 to 4.02GHz, which covers the required operating bands of DCS1800 (1710{1880MHz), PCS1900 (1850{1990MHz), UMTS2100 (1920{ 2170MHz), WLAN2400 (2400{2484MHz), LTE2300/2500 (2300{ 2690MHz) and WiMAX3500 (3300{3690MHz). In addition, good radiation characteristics such as symmetrical radiation pattern, moderate peak gain, low back radiation, and low cross-polarization are observed over the entire operating band.

A COMPACT INDUCTIVELY LOADED MONOPOLE ANTENNA FOR FUTURE UWB APPLICATIONS

A novel inductively loaded monopole for future ultra-wide- band (UWB) applications is presented. The antenna is compact and of small size (16mm £ 20mm £ 0:8mm), and ofier a very simple geometry suitable for low cost fabrication and straight forward printed circuit board integration. More speciflcally, the impedance matching of the classic printed inductively loaded monopole is improved by employment of the tapered microstrip feed line between K-connector and the printed monopole. By using this technique, impedance bandwidth (S11 < i10dB) from 3.03GHz to over 40GHz is obtained. Measured and simulated return loss curves are provided along with radiation patterns and gains, as a function of frequency. Compared to the recently reported UWB antennas, the presented antenna have smallest size, widest bandwidth, and simple conflguration to realize the application in UWB communication systems. Furthermore, symmetric radiation patterns and satisfactory gains make the presented antenna a suitable candidate for practical UWB applications.

A NOVEL DUAL-POLARIZED DIPOLE ANTENNA WITH COMPACT SIZE FOR WIRELESS COMMUNICATION

A novel dual-polarized dipole antenna with compact size is presented for wireless communication applications. The proposed antenna is composed of a dual-polarized cross dipole, a small-sized tapered re∞ector, a square patch director, and an octagon ring as a parasitic element. Low VSWRs ( 38dB) and symmetric broadside radiation patterns are also achieved. Two dual- polarized reference antennas are also developed. Contrast results show that the proposed antenna can obtain improved radiation patterns compared with the reference antennas. Moreover, the proposed antenna is very compact in size (0:52‚0 £ 0:52‚0 £ 0:32‚0, ‚0 refers to the center frequency of operating band), which achieves about 20% size reduction than Ref 2. Experimental results are also carried out to verify the simulation analysis.

A Compact and Broadband Microstrip Stacked Patch Antenna With Circular Polarization for 2.45-GHz Mobile RFID Reader

A compact and broadband microstrip stacked patch antenna with circular polarization (CP) for a mobile 2.45-GHz passive radio frequency identification (RFID) reader is presented. The proposed antenna consists of two stacked patches fed with an S-shaped impedance-matching network (IMN), which is connected by a probe. With the proposed S-shaped IMN feed technique, a good impedance matching and symmetrical broadside radiation patterns could be obtained. The CP operation could be attained simply by the upper parasitic patch rotating 90 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> sequentially based on the lower patch and truncating corners. Additionally, with four symmetric-L narrow slots on the patches, the compact operation could be obtained. The proposed reader antenna matching is optimized by regulating the sizes of the S-shaped IMN: <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$S_{\rm x}$</tex> </formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$S_{\rm y}$</tex> </formula> . Experimental results show that the reader antenna of size 58 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\, \times \,$</tex></formula> 58 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\, \times \,$</tex></formula> 11 mm <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^3$</tex></formula> has a 3-dB beamwidth of more than 91 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex> </formula> . The peak gain is optimized in the frequency range from 2.31 to 2.56 GHz of larger than 6 dBi, and it achieves 6.32 dBi in the center frequency 2.45 GHz. The voltage standing wave ratio (VSWR) <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${&lt;}2$</tex></formula> impedance bandwidth is larger than 15.1%.

Forward Scattering of Loaded and Unloaded Antennas

Forward scattering of antennas is related to antenna performance via the forward-scattering sum rule. The forward-scattering sum rule is an integral identity that shows that a weighted integral of the extinction cross section over all spectrum is proportional to the static polarizability of the antenna structure. Here, the forward-scattering sum rule is experimentally verified for loaded, short-circuit, and open-circuit cylindrical dipole antennas. It is also shown that the absorption efficiency cannot be greater than 1/2 for reciprocal linearly polarized lossless matched antennas with a symmetric radiation pattern in the forward and backward directions.

Dual-band dual-polarized printed antenna for wireless communication

A novel dual-band dual-polarized antenna design with high isolation and low cross-polarization is presented. An arc-coupled annular ring and a special coaxial-fed slot patch are employed as the radiating elements at lower and upper bands, respectively. Measurements show that the 10-dB impedance bandwidths reach 27.9% (1.66–2.19 GHz) and 18.4% (5.09–6.12 GHz). The port isolation for both bands is better than 30 dB. Moreover, stable and symmetrical radiation patterns at slanted polarizations are achieved, and the measured cross-polarization level is less than dB within the above-mentioned bands.

Design of a dual-polarized slot antenna with high isolation and low cross-polarization for wireless communication

A novel coaxial-feed dual-polarized slot antenna with high isolation and low cross-polarization is presented. Special slots are employed for symmetrical radiation patterns at slanted polarization and low cross-polarization under dB, which include two pairs of T-shaped slots and two pairs of cross-shaped slots in the radial directions of a circle patch. Moreover, high isolation of more than 36 dB between the two feeding ports is achieved by introducing two shorting pins. The experimental results demonstrate the proposed antenna is capable to operate over the frequency range of 2.23–2.91 GHz, suitable as the base station antenna for WiMAX applications.

High-Isolation XX-Polar Antenna

A new configuration of the dual-band and dual-polarized antenna is presented, which is fed by aperture coupling for the existing mobile communication systems working over 870-960 MHz (GSM) and 1710-2180 MHz (DCS/UMTS) frequency band. XX-Polar antenna stands for an antenna with dual-band and dual linear slant polarization. In this paper DU band stands for DCS/UMTS band. Measurement results show that the proposed antenna yields good broadside radiation characteristics including symmetric radiation patterns, low cross-polarization level ( ; 20 dB) and high isolation (>; 30 dB) at both bands. The designed antenna has an impedance bandwidth of 20.4% (790-970 MHz) for VSWR <; 1.5 in the lower band and 29.3% for VSWR <; 1.6 (1630-2190 MHz) in the upper band. The measured average gains are about 9.3-10.2 and 8.6-10 dBi in the lower and upper band, respectively. It is also promising for array antenna in various wireless systems.

Wide-Band Wide-Coverage Linear Array of Four Semi-Circular Sector Horns

A linear array antenna consisting of four semi-circular sector horns is proposed to achieve wide-band and wide-coverage radiation characteristics. The array can operate over a wide frequency band from 850 MHz to 2570 MHz and cover a wide range of 120° in the azimuth plane. Each semi-circular sector horn is fed by a centred coaxial probe loaded with a conducting cylinder to obtain a wide-band and symmetric radiation pattern of vertical polarization. Measured and simulated results of a designed array show its potential applications for base stations serving wide-range mobile users and other wide-band spectrum-monitoring systems.

A miniaturized switchable circularly polarized patch antenna controlled by a single diode operation

A novel switchable circularly polarized patch antenna with a compact size is proposed that uses only a single PIN diode. The proposed antenna consists of a corner-truncated square radiating patch with a cross-shaped slot on the ground, a triangular conductor, and one PIN diode. Because of the cross ground slot which is embedded on the diagonal direction, the resonant frequencies of each circular polarization sense are lowered about 41% for right-hand circular polarization and 38% for left-hand circular polarization. Moreover, by alternating the states of only one diode, a circular polarization sense is easily reconfigured without a radiating degradation. The simulated and measured results show that good CP characteristics are obtained with symmetrical radiation patterns at the lowered resonant frequencies. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2375–2378, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27070