Zhixi Liang

Multiband Monopole Mobile Phone Antenna With Circular Polarization for GNSS Application

A novel design of a multiband monopole mobile phone antenna with circular polarization for GNSS application is presented. The proposed antenna generates four resonant frequencies with branch lines and a shorted parasitic strip to obtain a wide operating band. With the definition of 2.5:1 VSWR, the bandwidth covers several wireless communication systems, including GSM (880 ~ 960 MHz), DCS (1710 ~ 1880 MHz), PCS (1850 ~ 1990 MHz), UMTS (1920 ~ 2170 MHz), WiBro (2300 ~ 2390 MHz) and ISM (2400 ~ 2483 MHz), and also covers GNSS, including COMPASS (1559.052 ~ 1591.788 MHz), GPS (1575.42 ± 5 MHz), GLONASS (1602 ~ 1615.5 MHz). A tuning stub is added to the ground plane and the feeding strip is mounted 45 ° at the corner to achieve circular polarization for GNSS application. The 3 dB axial ratio (AR) bandwidth (AR-BW) is obtained from 1540 to 1630 MHz, covering the L1 band of GNSS, including COMPASS, GPS and GLONASS. In the 3 dB axial ratio bandwidth, right hand and left hand circularly polarizations are obtained in different broadside directions, with the peak circularly polarized gain of more than 2.7 dBic. An equivalent circuit network is used to analyze the mechanism of circular polarization. Details of the proposed antenna parameters, including return loss, radiation characteristics, and AR spectrum are presented and discussed.

A Dual-Frequency Broadband Design of Coupled-Fed Stacked Microstrip Monopolar Patch Antenna for WLAN Applications

A novel dual-frequency broadband design of a stacked microstrip monopolar patch antenna is proposed for WLAN applications. The antenna is composed of a via-loaded ring on the bottom layer and a circular patch on the top layer, both of which are coupled-fed by a circular coupler. A broad lower band is generated by converging the TM01 and TM02 modes of the via-loaded ring, and a broad upper band is yielded by coupling the TM03 mode of the via-loaded ring and the TM02 mode of the circular patch. Measured results show that the proposed antenna provides a broad lower band from 2.28 to 2.55 GHz and a broad upper band from 5.15 to 5.9 GHz with a low profile of 6 mm. Monopole-like radiation patterns are obtained in the dual bands with peak gains in the lower and upper bands of about 5 and 6 dBi, respectively.

A Planar Quasi-Magnetic–Electric Circularly Polarized Antenna

A new planar quasi-magnetic-electric circularly polarized (CP) antenna is proposed. The antenna has a simple planar structure with a small size and a single feed, and produces an omnidirectional CP radiation pattern. It is based on a quarter-wave shorted patch connected with two printed strips. The tangential electric field at the main open aperture of the shorted patch can be considered as an equivalent magnetic current, while the two strips contribute two electric currents. With a single feed, the proposed antenna exhibits an inherent phase difference of about 90° for the two kinds of currents, and therefore, a CP radiation is obtained. The antenna is designed and fabricated. Measured results show that the antenna has an impedance bandwidth of 4.3%. In the band of interest, the antenna generates a circular polarization and an omnidirectional pattern in the plane perpendicular to the magnetic and electric currents, with an average axial ratio below 1.5 dB and a gain between 2.4 and 3.3 dBi.

A Novel Microstrip Quasi Yagi Array Antenna With Annular Sector Directors

A novel directional microstrip quasi Yagi array antenna is proposed to achieve a wide bandwidth with a low profile and a compact structure. The array is composed of a driven circular sector and annular sector directors. Arrays with both a single director and a dual director have been studied. Measured results show that the proposed antenna provides a stable high gain in a wide bandwidth with a low profile of 1.5 mm (0.03λ0 at 5.8 GHz). For an array using a single annular sector director, an impedance bandwidth of 13.6% (5.10-5.85 GHz) is achieved with a peak gain of 8.2 dBi. With two annular sector directors, the bandwidth is improved to 17.6% (5.05-6.02 GHz), and the peak gain is 10 dBi.

A Wide-Bandwidth Monopolar Patch Antenna with Dual-Ring Couplers

A new center-fed circular patch antenna with two coupled annular rings is presented. When the two annular rings are coupled properly, a wide band from 5.45 GHz to 7.16 GHz is achieved with a monopole-like radiation pattern. Measured results show that the antenna with a low profile of 0.027 wavelengths (at 5.45 GHz) has a bandwidth of 27.1% and a measured maximum gain of 6 dBi. The radiation pattern is omnidirectional and remains relatively stable within the operating band.

Biplanar Monopole With DSPSL Feed and Coupling Line for Broadband Mobile Phone

A biplanar monopole with a double-sided parallel strip line (DSPSL) feed and coupling line for broadband mobile phone is presented. The proposed antenna consists of a DSPSL feed and a coupling line, suitable for broadband operation (824-960/1710-2620 MHz). It just requires a small area of 15 × 40 mm2 on the circuit board, and it is configured along the boundary of the no-ground portion so that it can save much area, on which other electronic components can be put. The antenna is formed by a short strip line at the back side and a long strip line at the front. The overlapping part of them forms the DSPSL structure, which leads to a better impedance matching result. The long strip line contributes to cover the lower band (824-960 MHz), while the short strip line generates a resonant mode to cover the upper band (1710-2620 MHz). A coupling line alongside the long strip line and the ground are also formed to make the high resonant mode more effective. Details of the antenna are presented.

Microstrip Magnetic Monopole Endfire Array Antenna With Vertical Polarization

A new microstrip endfire array antenna with vertical polarization is proposed in this paper. The novel array element consists of two symmetrical rectangular patches on both sides of a substrate with two edges shorted and other edges opened. We use a cavity model to analyze the mechanism of the array element, which we find can work as a “magnetic monopole antenna.” The magnetic current on the open sides, which features quarter cycle sinusoidal variation, generates a tilted monopole-like radiation pattern. The tilted angle can be easily determined by the length-to-width ratios of the magnetic monopole antenna. A two-element endfire array and a four-element endfire array are proposed here to achieve endfire vertical polarization with a very low profile (3 mm). The two-element endfire array has a bandwidth from 2.42 to 2.48 GHz and a peak endfire gain of 5.3 dBi. With four array elements, the peak endfire gain can be enhanced to 7.7 dBi in a bandwidth from 2.40 to 2.48 GHz.

A Method of Designing a Dual-Band Sector Ring Microstrip Antenna and Its Application

A dual-band sector ring microstrip antenna operating at the TM11 and TM02 modes is analyzed and then designed in this communication. Unlike previous analyses that use only cavity model or transmission line, a simpler analysis using both models is proposed. Accordingly, several closed equations are derived. Such equations determine the relationship among three important units of construction, namely the radii, the angle, and its operating frequencies, and with the operating factors in a dual-band sector ring patch. The errors between the proposed method and the cavity model are acceptable. The field and radiation patterns of the sector ring patch are also discussed. In addition, these analyses and equations are applied to design a dual-band sector ring microstrip antenna for WLAN. A novel coupling sector ring patch is then proposed to improve the performance of the antenna. The experimental results are in good agreement with the analyses and the simulations. The impedance bandwidths of the antenna are about 40 and 900 MHz with consistent broadside radiation patterns at 2.4 and 5.5 GHz band. Additionally, their measured average gains are about 5.1 and 6.3 dBi, respectively.

A Multiband Monopole Antenna with the Inverted-Trapezoidal CPW Feeding

A multi-band monopole antenna with the improved inverted-trapezoidal coplanar waveguide (CPW) feeding is presented. The antenna has a simple planar structure, and occupies an area of 15 mm × 50 mm. The proposed antenna consists of an improved inverted-trapezoidal CPW-fed patch, and a series of monopole strips with different length. This monopole antenna utilizes the advantages of the CPW feeding to simplify the structure of the antenna into a single metallic level and achieve high antenna gain. The improved inverted-trapezoidal CPW-fed patch and a meander shorting strip lead to a better impedance matching result and multi-band operation. The experimental results of the proposed antenna are shown and discussed. The antenna generates two wide bands centered at about 900 and 2200 MHz to cover the GSM850/GSM900/DCS/PCS/UMTS/LTE2300/2500 bands and the 2.4 GHz WLAN operation. Meanwhile the antenna covers the 4 G bands of China Telecom (2370–2390 MHz/2635–2655 MHz), China Unicom (2300–2320 MHz/2555–2575 MHz) and China Mobile (1880–1900 MHz/2320–2370 MHz/2575–2635 MHz), too.

A Dual-Band Printed End-Fire Antenna with DSPSL Feeding

A novel dual-band printed end-fired antenna with double-sided parallel-strip line (DSPSL) feeding is presented. The DSPSL acts in wideband transition using balanced transmission. Two different modes of the parasitic patches allow the antenna to work in different bands. The printed antenna is designed as a quasi-Yagi structure to achieve directivity in the lower band, and the parallel rectangular patches serve as the parasitic director. These patches act as radiation patches with end-fire direction characteristics in the upper band. The measured bandwidths were 18.3% for the lower frequency band (2.28–2.74 GHz) and 12.6% for the upper frequency band (5.46–6.2 GHz).