1、外文翻译新的双频双极化开槽微带天线的设计方法A Novel Method for Designing Dual-Frequency Slot Patch Antennas with Two PolarizationsWU Di1, OH ISH I BA SH I H idekazu2, SEO Kazuyuk i2, I NA GA K IN aok i3(1. Department of Communication Engineering , Shang hai University , Shang hai 200072, China;2. Kojima R &D Center, Koji
2、ma Press Industrial Co Ltd , Aichi 4700207, Japan;3. Nagoya Institute of Technology, Nagoya 4668555, Japan)Abstract: This paper presents a new method for designing a dual-frequency patch antenna with circular and linear polarizations. Dual-frequency operations are behaved by etching two narrow slots
3、 close to the radiating edges of a rectangular patch. The circular polarization at the lower resonant frequency of the dual-frequency antenna can be achieved by setting a perturbation segment at an appropriate location in the patch element, and placing the feed point on the diagonal axis. Several ex
4、perimental results of a designed antenna show the good characteristics for circular and linear polarizations at both resonant frequencies.CLC number：TN821.1 Document code： AKey words: dual-frequency; slot patch antennas; linear polarization; circular polarizationIn radar and communication systems, d
5、ual-frequency operations are often required. Specially, in modern mobile global position system (GPS), it will be desirable that one of two frequencies is the circular polarization. Planar antenna has been investigated for multi-frequency very well since it is advantageous in low cost, low weight an
6、d conform ability. Early dual-frequency planar antenna is multilayered stacked-patch structure, and the radiating element is used to be circular1, annular2, rectangular3and triangular patches4. Recently, a dual-frequency antenna is introduced in which the structure is dingle layer patch with two slo
7、ts close to the radiating edges, and good performances of simultaneous impedance matching and gain are demonstrated for both resonant frequencies. However, all the conventional investigations are only for the case in which the antenna polarization is linear, while the dual-frequency antenna with cir
8、cular polarization has not been touched yet.In this paper, we present a design method of a dual-frequency antenna with circular and linear polarizations based on the conventional investigation for the dual-frequency linear polarization antenna57, Two resonant frequencies are determined by adjusting
9、the size of the patch element and the slot, as well as the location of the slot in the element. The key to obtain a circular polarization for an antenna is to satisfy the condition for exciting circular polarization, ie， the circular polarization can be excited by setting the perturbation segment ,a
10、t an appropriate location in the patch element, and by placing the feed point on the diagonal axis. We have experimentally obtained the circular and the linear polarizations at both lower and upper frequencies, and some experimental results will be demonstrated on the reflection loss at input port a
11、nd the radiation pattern of the antenna.1 Configuration of conventional dual-frequency patch antennaFigure 1 shows a configuration of a conventional dual-frequency antenna with linear polarization. Two resonant frequencies are behaved by etching two slots close and parallel to the radiating edges, a
12、nd the lower resonant frequency is determined by the outline size of the patch element, while the upper resonant frequency is determined by the size and the position of the two slots in the patch element. Because the slots are closely located to the radiating edges, a minor perturbation of the TM10
13、mode can be expected. As for unperturbed TM30 mode, since the slots are located where the current shall be significant, the current will be strongly modified, and a perturbed TM30 radiation pattern similar to the TM10 mode can be obtained.Our object in this investigation is to obtain a dual-frequenc
14、y antenna with both polarization in which the lower frequency is with a circular polarization and the upper frequency is with a linear polarization. For a square patch antenna with area of S fed by one port, a way to excite a circular polarization is to extend the length of two parallel subtends of
15、the patch element in order to set a perturbation segment s, and place the feeding point on the diagonal axis. When an appropriate perturbation is selected, a circular polarization with a good axial ratio can be obtained. Fig 1 Configuration of conventional dual-frequency antenna2Designing for dual-f
16、requency slot patch antennas with two polarizations In a conventional investigation for dual-frequency with linear polarization5 7 , to ensure agood radiation efficiency at both frequencies, the aspect ratio between the two sides of the patch istaken in the range (1)and the lower frequency is determ
17、ined by (2)where c is the velocity of light in free space， is the effective permittivity given by (3)and (4) (5)here (6)and the upper frequency is determined by (7)In above expression, the parameters of W, L, t, w, d, l are referred to Fig 2, and the is the dielectric constant of the substrate. Howe
18、ver, in this study, in order to obtain a circular polarization at the lower resonant frequency, the aspect ratio of the outline size of the patch will be changed so that the mentioned formulas above will not be completely satisfied.Fig 2 Configuration of dual-frequency We present a design method for
19、 dual-frequency slot patch antenna with two polarization as follows. Step 1 Design a square patch antenna with the desirable lower frequency f10 by using a conventional method. Step 2 Etch two slots close and parallel to the radiating to behave the dual-frequencies operation by using Eq (7). However
20、 the lower resonant frequency f10 will change, since the slots modify the current distribution of the TM10. Step 3 Adjust the size of the antenna element to obtain the desired lower resonant frequency. Step 4 Adjust the length and the width of the slots to obtain the upper resonant frequency f30. St
21、ep 5 Set perturbation segment and place the feed point on the diagonal axis of the antenna to obtain the circular polarization at the lower resonant frequency f10.3 Experimental results and discussion We experimentally designed a dual-frequency patch antenna with two polarizations. Figure 2 shows th
22、e configuration of the antenna, and the specifications are listed in Table 1. In this configuration of the antenna, we extended the L edge of the patch antenna to set the perturbation segment, and placed the feed point on the diagonal axis to achieve the circular polarization.Table 1 Specifications
23、of a dual-frequency patch antenna with two polarizationGPSVICSFrequency/GHz1.5752.5PolarizationCircularLinearReturn loss-15-15Gain3dB ic5dBi Figure 3 shows a measured reflection loss of a designed dual-frequency antenna fed by 50 coaxial probe. From this figure, it can be observed that two resonant
24、frequencies are achieves at desired frequencies 1.575GHz and 2.50GHz, which will be employed to mobile global position system(GPS) and vehicle information & communication system (VICS), and a good simultaneous impedance matching was obtained for reflection loss values -17dB at 1.575GHz and-27dB at 2
25、.5GHz.Fig 3 Frequency characteristics of reflection loss Figure 4 shows the axial ratio variation with the frequency for this designed antenna. It is seen that the best value of the axial ratio is about 1dB at 1.575GHz.Fig 4 Frequency characteristics of axial ratioFigure 5 shows the measured impedan
26、ce characteristics of the antenna in correspondence with Fig 3. It demonstrated that a perturbation is set for circular polarization at lower frequency 1.575GHz.Fig 5 Frequency characteristics of input impedance Figure 6 shows the radiation pattern of the circular polarization of the designed antenn
27、a at the lower resonant frequency 1.575GHz. In this figure, we used the unit dBic for gain, which can be calculated as follows where, GmaxdBi denotes the measured maximum gain in dBi, AR is the measured axial ratio. A gain of 3.7 dBic was found for patch antenna with circular polarization at 1.575 G
28、Hz.Fig 6 Radiation pattern of circular polarizationFinally, the radiation pattern of the linear polarization at the upper frequency 2.5GHz is shown in Fig 7. This is the perturbed TM30 mode, however, because the two slots exist in the patch, the shape of the radiation pattern of the perturbed TM30 m
29、ode becomes similar to that of TM10 mode. A gain of 5dBi was obtained for patch antenna with linear polarization at 2.5GHz.Fig 7 Radiation pattern of linear polarization4 Concluding remarksA novel design method for a dual-frequency patch antenna with both circular and linear polarization is presente
30、d in this paper. Two resonant frequencies are behaved by etching two slots close to the radiating edges in the rectangular patch, and the circular polarization at the lower resonant frequency is achieved by setting a perturbation segment in the patch element, and by placing the feed point on the dia
31、gonal axis. A dual-frequency antenna with both polarizations, which will be used to GPS and VICS for mobile communication, is designed by using presented method. As for measured result, it demonstrated that the designed antenna has two resonant frequency, in which one is a circular polarization with
32、 an axial ratio 1dB and gain 3.7 dBic at lower frequency, and the other is a linear polarization with 5dB i at the upper frequency.References :1Long S A , Walton M D. A dual-frequency stacked circular-disc antenna J. IEEE Trans Antennas Propagat, 1979, A P 27: 270 273.2Dahele J S, L ee K F, Wong D P. Dual frequency tacked annular-ring microstrip antenna J . IEEE Trans, 1987, A P 35 (11) : 1281 1285 .3Wang J , Fralich R, W u C, et al . Multifunctional aperture co
