Thiết kế một anten tái cấu hình theo đồ thị bức xạ ứng dụng cho thu phí điện tử trong hệ thống giao thông thông minh

Bài viết Thiết kế một anten tái cấu hình theo đồ thị bức xạ ứng dụng cho thu phí điện tử trong hệ thống giao thông thông minh trình bày: Đề xuất cấu trúc anten tái cấu hình theo tần số dựa trên anten dipole ứng dụng cho thu phí điện tử trong hệ thống giao thông thông minh. Anten bao gồm 5 dipole đặt trên mặt điện môi được nối hoặc ngắt với nhau bằng các PIN diode,.... Mời các bạn cùng tham khảo.
Nội dung trích xuất từ tài liệu:
Thiết kế một anten tái cấu hình theo đồ thị bức xạ ứng dụng cho thu phí điện tử trong hệ thống giao thông thông minhDESIGN OF A RADIATION PATTERN RECONFIGURABLE ANTENNAFOR ELECTRONIC TOLL COLLECTION IN INTELLIGENTTRANSPORT SYSTEMCHO T1,2Hoang Thi Phuong Thao , Vu Van Yem1422Electric Power University, Hanoi University of Science and Technology1. INTRODUCTIONWith the rapid development of wirelesscommunication, pattern reconfigurableantenna has received a considerableamount of attention in recent years.Pattern reconfigurable antenna is knowncharacteristic can adapt with changingsystem requirements or environmentalconditions [1]. A pattern reconfigurableantenna can provide different radiationpatterns, so it can replace a number oftraditional single antennas in system [2].Therefore, compared with traditionalantennas,theadvantagesofreconfigurable antennas are multifunction,flexibility, and help to reduce cost andoverall size of system [3]. Furthermore,because of adjustable radiation patterns,reconfigurable antenna can be directedtoward the access point, so it can savepower for transmission and reduce noise[4].So far, there is a lot of researches onradiation pattern reconfigurable antennaswith different techniques, in which PINdiode is used popularly. In [5], radiationpattern of a compact planar antenna canbe switched from different directionsusing PIN diodes, whereas in [6], itcan steered between bidirectional andunidirectional. In [7, 8], the proposedantennascanswitchbetweenomnidirectional pattern and directionalpattern by controlling PIN diodes.Another radiation pattern reconfigurableantenna using PIN diode is proposed in[9] can select between two beamdirections. However, the bandwidth ofthis antenna is narrow. A planar printeddipole antenna with reconfigurable patternproperties in [10] is able to archive twoopposite directions by switching four PINdiodes. This antenna has high gain, butincrease in the overall antennadimensions.In this paper, we propose a radiationpattern reconfigurable antenna based onprinted dipole structure which can operateat 5.8 GHz band for Electric TollCollection (ETC) in Intelligent TransportSystem (ITS). This antenna includes fiveelements connected or disconnected byPIN diodes. A conventional surfacereflective structure is applied under theground of the antenna for gainenhancement.By switching these diodes, the antennacan operate at three configurations withbeamwithout change in resonant frequency.The bandwidths in any configurationsachieve about 200MHz which is suitablefor ETC applications. Overall dimensionof the antenna is 40 × 60 × 13 mm3. Theantenna archives gain above 5.37 dBi inthree configurations.The remainder of the paper is organizedas follows. Section 2 describes theantenna design. Section 3 presentssimulation and measurement results withsome discussion. Finally, the conclusionof the paper is given in Section 4.2. ANTENNA DESIGNThe structure of the proposed antenna isgiven in figure 1. The antenna includesthe main radiation part and the reflector.The main radiation part of the antennalooks like an array of five printed dipoleswith each dipole placed on front side andback side of the substrate. These dipolesare fed via a central transmission line. Thetransmission line with two microstriplines are designed on the opposite sides ofa dielectric substrate. The reflector is afull copper surface which is used for gainenhencement. The antenna achieves thebest simulated gain when the distancefrom the substrate to the copper is 13 mm.The substrate of antenna has the thicknessh=1.6 mm, the relative permittivity r=4.4and the loss tangent = 0.02. The overallsize of antenna is 40 mm × 60 mm ×13 mm.Figure 1. Antenna structure: dark lines on the front side of the dielectric substrate,transparent ones on the back (front view and side view)The width of the transmission line ischosen to ensure the input impedance atfed point to be 50line is on two side of the substrate, it iswith the width of W and the substratethickness of h/2. We can calculate thewidth of transmission line from theequation (1) [11].120Z0eWW1.393 0.667 ln1.444hh(1)where Z0 is impedance of the transmissionline (25e is effective permittivity oftransmission line given approximately by:1re1r2212h1W12(2)The length of a single dipole for adesigned resonant frequency fr is:LDc2 fr(3)ewhere c is the speed of light in free-space.Now, we compute the width Wd of thedipole. We select the dipole characteristictransmission line. To achieve thecharacteristic impedance Zinradius of the cylindrical dipole iscomputed by the equation (4) [12]:Zin 120 lnLDaD2.25(4)where aD is the radius of the cylindricaldipole, LD is the length of the dipole. Forprinted dipole, its width Wd is calculated[13]:Wd= aD ...