A Simple Ultrawideband Planar Rectangular Printed Antenna With Band Dispensation

1. A Simple Ultrawideband Planar Rectangular PrintedAntenna With Band Dispensation 授課老師:陳文山 學生:陳瑞傑

2. Directory • Introduction • ANTENNA CONFIGURATION -Brief description of the antenna configuration -UWB Antenna Design -Describes the design method and simulation results using Ansoft HFSS. Software • Results and discussion • Conclusion

3. Introduction • Abstract—Acompact planar ultrawideband (UWB) antenna with band notched characteristics is presented. Modification in the shape of radiation element and ground plane with two symmetrical bevel slots on the lower edge of the radiation element and on the upper edge of the ground plane makes the antenna different from the rectangular printed monopole. These slots improve the input impedance bandwidth and the high frequency radiation characteristics. • With this design, the reflection coefficient is lower than 10 dB in the 3.1–10.6 GHz frequency range and radiation pattern is similar to dipole antenna. With the inclusion of an additional small radiation patch, a frequency-notched antenna is also designed and good out of band performance from 5.0–6.0 GHz can be achieved. Measured results confirm that the antenna is suitable for UWB applications due to its compact size and high performance. 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO1, JANUARY 2010

4. ANTENNA CONFIGURATION shows the geometry of the proposed antenna. It consists of a rectangular radiation patch with symmetrical bevel slots placed on the lower side of the patch and a partially modified rectangular ground plane with symmetrical bevel slots located on its upper side. A small rectangular patch with dimensions and, printed on the bottom side of the substrate is connected to the 50 line through via-hole to produce a notched band in the vicinity of 5.5 GHz and thus prevents the interference with WLAN systems. The antenna was implemented on an inexpensive FR4 substrate with a thickness of 0.76 mm and relative permittivity of 4.4. Fig. 1. Configuration of the proposed band notched UWB printed antenna L1= 30mm, W =18mm, l1=14.4mm l2 =14.4mm, g = 1.2mm, L = l1+l2+g, w1 = 3.5mm, h = 3mm, s = 11mm lf= 15.6mm, Wf = 1.4mm , a=5.3mm b=7mm 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO1, JANUARY 2010

5. showsthe simulated and measured reflection coefficient curves. The measurement confirms the UWB and band-rejection characteristics of the proposed antenna, as predicted in the simulation. The antenna covering the full UWB band(3.1–10.6GHz)is first described. Then the new band notchedstructure which is equivalent to series LC circuit, is investigated.The effects of changing the geometric parameters oftheproposed antenna on impedance, bandwidth and radiation patternare discussed. Fig. 2. Measured and simulated reflection coefficients of the proposed UWB antenna. 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO1, JANUARY 2010

6. Figs. 3 and 4 show the variation of the reflection coefficients with frequency for different dimensions of the bevel slots. It is seen that in the absence of bevels,w1 = 0 mm , the reflection coefficient behavior at low frequencies is identical to a narrow band dipole with current mainly distributed over the radiation patch and the ground plane. The placing of slots significantly Improves the higher band impedance matching as the shaping of the lower edge of the radiation patch has a substantial effect on the impedance matching of printed monopole antennas In other words, by properly choosing the dimensions of slots, impedance bandwidth can be enhanced. From the simulated results in Figs. 3 and 4, it occurs when w1 = 3.5 mm and h1 = 3 mm Fig. 3. Simulated reflection coefficients for the proposed antenna of various bevel widths (W1) with a fixed value of bevel height (h1) = 3 mm, a = b = 0mm, Other parameters are the same as given in Fig.1. Fig. 4. Simulated reflection coefficients for the proposed antenna of various bevel heights (h1) with a fixed value of bevel width (w1) = 3.5 mm. a = b = 0 mm . Other parameters are the same as given in Fig. 1. 資料來源:THOMAS AND SREENIVASAN: A SIMPLE UWB PLANAR RECTANGULAR PRINTED ANTENNA

7. Simple Formula for Resonant Frequency where W is the width of the rectangular disc The lower frequency f Lis given by By equating the area of the planar printed configuration to that of a cylindrical wire of length h At fundamental resonance, the length of cylindrical dipole for real input impedance is given by 資料來源:THOMAS AND SREENIVASAN: A SIMPLE UWB PLANAR RECTANGULAR PRINTED ANTENNA

8. At fundamental resonance, the length of cylindrical dipole for real input impedance is given by From the above equations, the resonant frequency is given by where and are in centimeters If l1 and denote the length of the ground plane and radiation patch respectively and is the gap between them, then can be expressed as l1 + l2 + g. 資料來源:THOMAS AND SREENIVASAN: A SIMPLE UWB PLANAR RECTANGULAR PRINTED ANTENNA

9. Similarly if r1 and r2 represent the radius of equivalent cylindrical dipole corresponding to the ground plane and radiation patch, then 2r can be expressed as r1+r2 (In the case of cylindrical dipole, r1 and r2 can be considered as the radius of the dipole arms and r1 = r2 = r). where A1 and A2 are the area of the ground plane and the radiation patch respectively.l1 ,l2 ,r1 ,r2 and g are in centimeters. 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

10. TABLE I EFFECT OF WIDTHS OF THE GROUND PLANE AND RADIATION PATCH ON RESONANT FREQUENCY FOR THE PROPOSED ANTENNA WITH CONSTANT STEP WIDTHS (s = 11 mm). DENOTES THE WIDTH OF THE GROUND PLANE AND Wr DENOTES THE WIDTH OF THE RADIATION ELEMENT 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

11. TABLE II SIMULATED VARIATION OF RESONANT FREQUENCY WITH CHANGE IN DIELECTRIC CONSTANT OF THE SUBSTRATE MATERIAL FOR THE PROPOSED ANTENNA WITHOUT BEVEL SLOTS 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

12. TABLE III COMPARISON OF RESONANT FREQUENCIES FOR VARIOUS TYPES OF PRINTED MONOPOLE ANTENNA CONFIGURATIONS 資料來源:THOMAS AND SREENIVASAN: A SIMPLE UWB PLANAR RECTANGULAR PRINTED ANTENNA

13. Figs. 5 and 6 show the variation of simulated reflection coefficients with different values of and . Fig. 5. Simulated reflection coefficients for the proposed antenna of various notch element length a with a fixed notch element width b = 7 mm . Other parameters are the same as given in Fig. 1. Fig. 6. Simulated reflection coefficients for the proposed antenna of various notch element width b with a fixed notch element length a = 5.3 mm . Other parameters are the same as given in Fig. 1. 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

14. TABLE IV EFFECT OF WIDTH OF THE RECTANGULAR PATCH ON RESONANT FREQUENCY OF THE REJECTED BAND FOR CONSTANT PATCH LENGTH a = 5.3 mm 􀀀 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

15. TABLE V EFFECT OF LENGTH OF THE RECTANGULAR PATCH ON RESONANT FREQUENCY OF THE REJECTED BAND FOR CONSTANT PATCH WIDTH 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

16. Fig. 7. Simulated current distribution of the proposed antenna (a) pass-band (at 3.5 GHz) and (b) stop-band (at 5.5 GHz). proposed antenna is indeed controlled by the length and width b of the rectangular patch. 資料來源:IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 1, JANUARY 2010

17. MEASURED ANTENNA PERFORMANCE Fig.8.Measured radiation patterns of the proposed band notched UWB antenna in x-y plane ( Etheta and Ephi component). Fig.9.Measured radiation patterns of the proposed band notched UWB antennaInx-zplane ( and component). frequencies, the patterns deviate from symmetry, as can be seenat 6.0 and 9.0 GHz. 資料來源: THOMAS AND SREENIVASAN: A SIMPLE UWB PLANAR RECTANGULAR PRINTED ANTENNA

18. Fig. 10. Measured and simulated gain of the proposed band notched UWB antenna. Fig. 11. Photograph of the fabricated antenna. shows the measured and simulated gains of the realized antenna from 3–11 GHz Close agreement between measured and simulated results can be found. The measured antenna gain variations are less than 2 dB throughout the desired UWB frequency band and a gain drop of 6–7 dB occurs at 5.5GHz. A photograph of the proposed antenna when printed on FR4 substrate is displayed in Fig. 11. 資料來源: THOMAS AND SREENIVASAN: A SIMPLE UWB PLANAR RECTANGULAR PRINTED ANTENNA

19. Conclusion The overall antenna size is 30 mm x18 mm x 0.76 mm. The antenna, compact and simple, has minimum design parameters which have been investigated for optimal design. an approximate empirical formula is presented to calculate the lowest resonant frequency for the planar printed monopole/dipole antennas in general The present design can easily be extended to dual or triple band-notched antennas. The operating bandwidth of the proposed antenna covers the entire frequency band from 3.1–10.6 GHz. Both simulated and measured results suggest that the proposed antenna is suitable for UWB communication applications and at the same time dispenses the interference with WLAN systems.

20. 感想 這篇是在說一個矩形平面超寬帶印刷天線，該天線結構緊湊，操作簡單，最小的設計參數，進行了研究設計。經過公式的計算，模擬測試出天線適合於超寬帶通信的應用。