Guanlong Huang

A MINIATURE UWB SEMI-CIRCLE MONOPOLE PRINTED ANTENNA

A semi-circle monopole printed antenna is proposed. Its radiation unit and the ground plane are in the same shape, and both of them are coplanar-printed. The antenna is fed by a microstrip line, which is connected to the radiation unit through a via-hole. The measured impedance bandwidth is about 3.1GHz{15.1GHz with VSWR < 2, and the ratio bandwidth can reach 4:9 : 1. The omnidirectional characteristic is also excellent in H-plane. Moreover, because of the introduction of the semi-circle radiation unit and the ground plane, the length of the radiation unit can be miniaturized in polarization direction, which is only 14% of wavelength of the lowest operating frequency. The antenna size is just 29mm £ 29:5mm £ 1:0mm, which can make it well integrate into UWB communication systems.

Novel Printed Yagi-Uda Antenna with Highgain and Broadband

A high-gain and broadband printed Yagi-Uda antenna is proposed. The microstripline-to-balance microstripline technique is adopted in the feeding mode of the active dipole, which can help to realize the balanced-unbalanced transformation. The ground of the microstrip feeding line can function as a re∞ector, and both the longer re∞ector and the shorter director can also help the antenna achieve wideband. By altering the area of the substrate, the antenna gain can be efiectively improved. A printed Yagi-Uda antenna operating at 3.5GHz has been designed and manufactured. Both the simulated and measured results indicate that there is a high positive correlation between antenna gain and the substrate area extended from the front of the director, and antenna broadband characteristic would not be changed at the same time. Moreover, the impedance bandwidth of the proposed antenna can achieve 27.4%, and the maximum gain in the operating band can reach 10.6dBi.

Design and experiment of a high gain axial-mode helical antenna

A high gain axial-mode helical antenna with parasitic element is proposed. A metal wafer is used as parasitic element, loaded in the front of general axial-mode helical antenna to achieve the aim of improving antenna gain. The diameter of the wafer and the distance between the wafer and the end of the helical wire, which can influence the antenna characteristics, are both simulated and optimized by CST Microwave Studio®, a 3-dimentional full wave electromagnetic simulation software. Prototype of the proposed antenna is manufactured according to the optimal simulated results and measured in the microwave anechoic chamber. Compared with general antennas, both the simulated and measured results indicate that the helical antenna with parasitic element can boost 0.8dB in gain under the circumstance of increasing 8.3% of the antenna axial length. In addition, this antenna can achieve the band 2.1–2.7GHz in its operating bandwidth, and the maximum axial ratio is up to 1.3dB in pass-band, which is not subject to the impact of parasitic element. The proposed antenna can applied in WLAN systems.

Multiband printed monopole antenna with square-nested fractal

A kind of novel multiband monopole antenna with square-nested fractal is proposed and designed, which is nested with a series of similar square elements. The antennas can synchronously operate in multiple frequencies, covering the four required frequencies, 2.4GHz/3.5GHz/5.2GHz/5.8GHz, for WLAN/WiMAX application. The antenna surface currents are simulated by CST Microwave Studio®, a 3-dimension full-wave electromagnetic simulator, and the multiband operating mechanism has been explained from analysis of the simulated results. Then model of the proposed monopole antenna fed by coplanar waveguide has been obtained. Finally, prototype of the antenna has been manufactured and measured in anechoic chamber. The results well match the simulated, which verify the feasibility of design idea. Moreover, these antennas are miniature and the design idea can be easily applied into other types of nested structure, the features of which make the proposed antenna has promising application in multiband fields.

Research on Broadband and High-Gain Quasi-Yagi Antenna and Array

In order to obtain broadband and high-gain, a sort of planar printed quasi-Yagi antenna element and array, which operating in S-band, are proposed. The antenna element can be divided into two parts: the feeding unit and the radiation unit. Effects of major parameters on antenna performance are simulated and studied through electro-magnetic simulation, and the optimal design of the antenna element has been obtained. In addition, binary array based on the quasi-Yagi antenna element is devised to enhance the gain. Prototype antennas according to simulation results have been fabricated and measured. Experimental results show that the antenna element can operate at 2.8-4.5GHz, and the average gain is 5.5dBi. The operating frequency range of the antenna array is 2.9-4.3GHz, and the average gain is 7.5dBi. Both the antenna element and array have advantages of broadband and high-gain, which can be widely used in wireless communication system.

High-gain planar TEM horn antenna fed by balanced microstrip line

A printed TEM horn antenna with high gain fed by balanced microstrip line is proposed. The radiation part of the antenna consists of two symmetrical triangular metal slice branches printed on the FR-4 substrate with 1.5mm thickness. The two branches are fed by balanced microstrip line. The antenna is simulated by software CST MICROWAVE STUDIO® and the equivalent adopted dipole model is proposed to describe the radiation characteristic of the antenna. The simulated results indicate that the frequency range is from 1.64GHz to 5GHz with reflection coefficient less than −6dB, and the typical gain value is 8dB in the operating bandwidth. In order to improve antenna gain without influencing the bandwidth, the length of the dielectric slab should be extended appropriately in the main radiation direction. By extending the length of the dielectric slab appropriately in the main radiation direction, the antenna gain can be improved significantly without influence on the bandwidth. The prototype has been fabricated and measured in microwave anechoic chamber which is coincident with the simulated results. This antenna can be widely applied in the UWB field.

Study on a Miniature UWB Wafer-Dipole Printed Antenna Fed by Balanced Micro-Strip Line

A novel wafer-dipole printed antenna fed by balanced microstrip line is proposed, and the adoption of the balanced microstrip line can efiectively solve the feeding problem of the UWB dipole antenna. The wafer-dipole and a branch of the balanced microstrip line are printed on one side of FR-4 substrate (1mm thickness), and the later is connected to a wafer directly, while the other branch is printed on the back side and connected to the other wafer with a via-hole. The measured results show that the antenna impedance bandwidth is from 3.0GHz to 15.0GHz with VSWR < 2, and the ratio bandwidth is about 5 : 1. Moreover, the antenna size is just 40mm £ 20mm with simple structure, which is well suited for short-distance UWB communications.

Printed Direct-Antenna with Skirted Active Dipole

In order to improve the direct-antennas operating bandwidth, a printed direct-antenna adopting skirted dipole antenna as active dipole is proposed. The antenna is a single-face PCB structure and printed on the FR-4 substrate with 1.5mm thickness. The skirted dipole antenna is fed by coplanar waveguide, both sides of which are printed metal straps, used as the director and reflector respectively. The structural parameters are optimized by CST MICROWAVE STUDIO® and the prototype has been fabricated according to the simulated results and measured in microwave anechoic chamber. The experimental results indicate that the operating bandwidth is from 2.60GHz to 3.95GHz with reflection coefficient less than -10dB, and the in-band gain is higher than 4.5dBi, both of which match the simulated results well. Moreover, the compact size of the antenna is just 49mm×45mm (0.53λ0×0.49λ0). These advantages can promise the proposed antenna to be widely applied in WiMAX systems.