Kunpeng Wei

Design of a Wideband Horizontally Polarized Omnidirectional Printed Loop Antenna

This letter presents the design of a novel wideband horizontally polarized omnidirectional printed loop antenna. The proposed antenna consists of a loop with periodical capacitive loading and a parallel stripline as an impedance transformer. Periodical capacitive loading is realized by adding interlaced coupling lines at the end of each section. Similarly to mu-zero resonance (MZR) antennas, the periodical capacitive loaded loop antenna proposed in this letter allows current along the loop to remain in phase and uniform. Therefore, it can achieve a horizontally polarized omnidirectional pattern in the far field, like a magnetic dipole antenna, even though the perimeter of the loop is comparable to the operating wavelength. Furthermore, the periodical capacitive loading is also useful to achieve a wide impedance bandwidth. A prototype of the proposed periodical capacitive loaded loop antenna is fabricated and measured. It can provide a wide impedance bandwidth of about 800 MHz (2170-2970 MHz, 31.2%) and a horizontally polarized omnidirectional pattern in the azimuth plane.

A MNG-TL Loop Antenna Array With Horizontally Polarized Omnidirectional Patterns

A horizontally polarized omnidirectional planar loop antenna that employs an artificial mu-negative transmission line (MNG-TL) is proposed. The MNG-TL is designed using periodically loaded parallel-plate lines. The reactive loading is inspired by the zeroth-order resonator (ZOR), which has a propagation constant of zero. Due to the unique property of an infinite wavelength, the MNG-TL loop antenna presented in this paper allows current along the loop to remain in phase so that a horizontal polarized omnidirectional pattern is generated. A series-fed array, which is composed of four MNG-TL loop antennas and operates at 2.4 GHz band, is designed, fabrication, and measured. The MNG-TL loop antenna array offers a horizontally polarized omnidirectional radiation pattern with enhanced gain of 6.5 ~ 7.9 dBi and measured radiation efficiency exceeding 85% for covering bands. The concept extends the degrees of design freedom for horizontally polarized omnidirectional antenna array.

A Novel Hybrid-Fed Patch Antenna With Pattern Diversity

Abstract-In this letter, a novel hybrid-fed circular patch antenna operating with TM11 and TM01 modes is presented. By making use of a hybrid feed network, the two modes can be operated at an overlapped frequency range for 2.4-GHz WLAN applications, while TM11 mode reveals good broadside radiation patterns and TM01 mode shows monopole-like radiation patterns. The proposed antenna is fabricated and tested. The measured gain for the broadside mode is 7.1-9.1 dBi from 2.16 to 2.72 GHz (23.0%), and for the conical mode 3.4-4.3 dBi from 2.14 to 2.64 GHz (20.5%). High isolation (<; -40 dB) between the two feeding ports for the entire impedance bandwidth of the proposed antenna is achieved. The planar dual-port antenna provides different patterns and polarizations to take advantage of the pattern and polarization diversity for modern mobile communications.

DESIGN OF A DUALBAND OMNIDIRECTIONAL PLANAR MICROSTRIP ANTENNA ARRAY

This paper proposes and designs a new method of dualband omnidirectional planar microstrip antenna array. A cascade of transposed microstrip lines have been adapted to produce efiective antenna structures that radiate omnidirectionally, with high e-ciency, low re∞ection, and useful radiation patterns. In this paper, the antenna structure has been found to have low-pass characteristics due to the periodic discontinuities at the transposed junctions. The analysis and design of the low-pass characteristic are performed according to the fllter theory of periodic structures and full-wave simulation. Therefore, a relatively higher frequency radiating array is appropriately designed with a low-pass flltering attribute, which prevents the lower frequency radiators from resonating at the relatively higher frequency. An air gap between adjacent transposed sections is proposed in order to enhance impedance matching, and a fork shape stub at the end is used as a virtual short point to enhance radiation at the higher frequency. Finally a single port dualband omnidirectional antenna array is obtained by locating the higher frequency radiating array with low-pass flltering attribute near the antenna feed and a relatively lower frequency radiating array at the end. An example of a dualband omnidirectional planar array is demonstrated experimentally, which operates at 2:32 » 2:56GHz and 5:65 » 6:10GHz with S11 < i10dB and a stable radiation pattern, and corresponding gains of 7:0 » 7:6dBi and 6:9 » 7:9dBi respectively.

A Triband Shunt-Fed Omnidirectional Planar Dipole Array

A novel shunt-fed triband printed two-element collinear dipole array is presented in this letter. The planar dipole array configuration is designed using two shunt-fed back-to-back dipole elements with omnidirectional pattern. The motivation for this work was to devise a novel feed structure that has an advantage of structural simplicity with good performance. The proposed antenna can provide the required bands of GSM850 (824-894 MHz), DCS (1710-1880 MHz), and PCS (1850-1990 MHz) with S11 <; -10&nbsp; dB. A prototype array antenna is fabricated and measured. Good omnidirectional radiation with gain variations less than 1.5 dBi in the azimuth plane has been obtained. Enhanced antenna gain about 3.4 3.8 dBi for GSM850 band and about 3.85.5 dBi for DCS/PCS bands are achieved. It is significant that the designed triband dipole array maintained good radiation efficiency values at all bands.

Periodic Leaky-Wave Antenna Array With Horizontally Polarized Omnidirectional Pattern

A novel periodic leaky-wave antenna for broadside radiation with horizontally polarized omnidirectional pattern is proposed, designed and demonstrated experimentally. The objective is to achieve a horizontally polarized omnidirectional antenna array with highly directive beam. The proposed structure is based on combining the rotating electric field method and a leaky-wave antenna design. By properly designing a unit cell with a pair of crossed dipoles spaced at a distance approximately equal to λg/4 at the center frequency, not only omnidirectional radiation pattern with horizontal polarization is obtained by crossed dipoles fed in phase quadrature, but also the open-stopband effect exhibited at broadside scan is significantly reduced. The analysis and design of this structure are performed on the basis of a simple equivalent network model. A finite structure formed by 16-unit cell (32-element) for broadside beam is developed at the 2.4 GHz band, which offers a horizontally polarized omnidirectional radiation pattern with enhanced gain of 9.9-10.6 dBi and measured radiation efficiency of 90% for the covering bands.

A Dual Circularly Polarized Waveguide Antenna With Bidirectional Radiations of the Same Sense

A dual circularly polarized waveguide antenna with bidirectional radiations of the same sense is proposed in this communication. Bidirectional circular polarization (Bi-CP) of the same sense was obtained by two identical rectangular metal slices installed on one lateral side of the waveguide with an intersection angle of 45°. These two metal slices were horizontally perpendicular to each other and vertically spaced by a quarter guided wavelength. A rat-race coupler was employed to excite the two metal slices with the same amplitude, but with a 0° or 180° phase difference depending on the selection of two inputs. One sense of Bi-CP was realized when the two metal slices were fed in phase and the opposite sense of Bi-CP could be obtained when they were fed out of phase. A prototype for 2.4-GHz WLAN application was tested to verify our design. The measured common bandwidth for 10-dB return loss and 3-dB axial ratio at the two feed ports was 230 MHz (9.6%, 2.29-2.52 GHz) and 210 MHz (8.6%, 2.35-2.56 GHz), respectively. The measured isolation between the two feed ports was better than 30 dB over the whole operating band.

Design of a Ring Probe-Fed Metallic Cavity Antenna for Satellite Applications

This communication presents the design of a novel ring probe-fed metallic cavity antenna with circular polarization for satellite applications. The motivation for this work is to propose a novel design that has the advantage of electrically large size and improved 3-dB axial-ratio bandwidth in the Ku-band and other higher-frequency bands as well as low cost and easy fabrication. The resonant mode and circular polarization of the proposed antenna is excited by a ring probe. To verify the design concept, a brass C-band antenna prototype of the proposed antenna is fabricated and measured. The measured impedance bandwidth for |S11| ≤ -10 dB and 3-dB axial-ratio bandwidth are 1.08 GHz (6.94 GHz to 8.02 GHz) and 0.80 GHz (7.11 GHz to 7.91 GHz), respectively. The 3-dB axial-ratio bandwidth of the antenna is 10.7%. The measured gain is about 8.3 dBic across the whole 3-dB axial-ratio bandwidth. Very good consistency between the measurement and simulation for the return loss and radiation patterns is achieved.

A Broadband Patch Antenna With Tripolarization Using Quasi-Cross-Slot and Capacitive Coupling Feed

This letter presents a novel design of patch antenna with quasi-cross-slot and capacitive coupling feeding to achieve tripolarization with high isolation over a wide bandwidth. Two degenerate TM11 modes and one TM01 mode of the circular patch antenna are generated to realize three orthogonal polarizations. By using the proposed quasi-cross-slots, good measured isolations (better than 20 dB) were obtained. The measured impedance bandwidths of the proposed antenna ports are 2.13-2.58, 2.13-2.43, and 2.13-2.58 GHz, respectively. Details of the proposed design and measured results are presented and discussed.

Design of a Coplanar Integrated Microstrip Antenna for GPS/ITS Applications

This letter presents a novel low-profile coplanar multifunctional microstrip antenna for both global positioning system (GPS) and intelligent transportation system (ITS) applications. The multifunctional antenna consists of two parts: a directional coupled square-ring patch antenna and a center-fed square-ring loaded patch antenna. A coplanar simple single-fed method is proposed in the directional coupled square-ring patch antenna, which operates at the fundamental TMn mode with right-handed circular polarization at the GPS L2 frequency of 1.227 GHz. More-over, the square-ring is also utilized to load the center-fed square patch antenna at TM02 mode with a vertical linear polarization for ITS application, which considerably increases the impedance bandwidth. Very good consistency between the measurement and simulation for the return loss and radiation patterns is achieved.