LEAKY-WAVE ANTENNA USING SIW WITH TRANSVERSE SLOT SWETA KUMARI 1, SINEE KUMARI 2 1 Department of Electrical and Electronics Engineering, R V S C E T, Jamshedpur ksweta98@yahoo.in 2 Department of Electronics and Communication Engineering, R T C Institute of Technology, Ranchi sineekumari24@gmail.com ABSTRACT: A transverse slotted SIW Leaky Wave antenna which works in TE10 mode is proposed. The follow of current in the top surface of SIW is interrupted by introducing transverse slot. Simulation results demonstrate that three modes (a leaky mode, a proper waveguide mode, and a surface waveguide mode) can propagate in the proposed structure and wave numbers of the mode are calculated. The losses such as leakage loss are analyzed. The proposed antenna has a wide impedance bandwidth and a narrow beam. Keywords: Substrate Integrated Waveguide, Antenna, Leaky Wave, Impedance bandwidth [1] INTRODUCTION: In this project, we propose a leaky-wave antenna based on SIW technique. This proposed antenna works in the TE 10 mode of the SIW. Leakage is obtained by introducing a periodic set of transverse slots on the top of the SIW, which interrupt the current flow on the top wall. It is seen that by changing the shape of slots the performance characteristics of proposed antenna will change also three modes (a leaky improper waveguide mode, a proper waveguide mode, and a surface-wave-like mode) can all propagate on this structure.this type of SIW leaky-wave antenna has a wide impedance bandwidth and a narrow beam that scans with frequency. The transverse slotted rectangular waveguide works as a leaky-wave antenna having frequency beam-scanning capability, with an orthogonal polarization from the conventional travelling-wave slotted antenna [6]. Because of the polarization, the transverse slotted rectangular waveguide can scan from near broadside to end-fire if the waveguide is filled with a dielectric material [2]. It consists of a wide micro-strip line that is shorted at the edges with conductive vias, acting as a rectangular waveguide. The SIW has been widely developed for integrated microwave and millimeter-wave components and antenna. Sweta Kumari And Sinee Kumari 1
LEAKY-WAVE ANTENNA USING SIW WITH TRANSVERSE SLOT The proposed SIW leaky-wave antenna, shown in Fig-1, not only maintains the advantages of transverse slotted rectangular waveguide, but also has the advantages of SIW including low cost and ease of fabrication. This antenna has a simple structure and is easy to feed with a micro-strip line. This antenna scans in the forward quadrant as frequency changes. Because of the polarization, it can radiate well at end-fire when an infinite (or large) ground plane is present. (However, it is difficult to obtain a beam radiating at exactly end-fire if a finite ground plane is used due to finite ground diffraction effects.) Since the transverse slotted SIW antenna works similarly as a transverse slotted rectangular waveguide, we analysis this structure based on the theory of a transverse slotted rectangular waveguide [2]. A leaky (improper) waveguide mode, a proper waveguide mode, and a surface-wave-like mode can all propagate in the transverse slotted SIW antenna just as in the transverse slotted rectangular waveguide. The leaky waveguide mode is an attenuated mode that typically dominates above the cutoff frequency of the TE 10 mode in the closed rectangular waveguide. The proper waveguide mode is a bound mode that has no attenuation for a lossless structure (where the conductor and the dielectric are lossless). Both the leaky waveguide mode and proper waveguide mode have most of their power stored inside the waveguide and represent a perturbation of the closed waveguide (the former dominates in the fast-wave region, the latter in the slow-wave region). The surface-wave mode is also a proper bound wave, but this mode has most of its power stored at the surface of the waveguide and not inside the waveguide, so this mode does not represent a perturbation of the closed rectangular waveguide. For the improper leaky waveguide mode K pn, is chosen so that the imaginary part of K pn is positive for n=0 and negative for all other n. For the proper waveguide mode or the surface-wave mode solution, K pn is chosen so that the imaginary part of K pn is negative for all n. When the antenna radiates not too close to end-fire, it works as a leaky-wave antenna, and the radiation is mainly due to the leaky wave, which is fast wave. However, result show that when this antenna radiates near end-fire, it becomes a surface-wave antenna since the radiation is mostly produced by a surface wave, which is slow wave. [2] PROPOSED DESIGN: In this paper we propose SIW based leaky wave antenna based on equation presented in paper [23] for p and d arbitrary values for other parameters. The various parameters with their respective values are given below Sweta Kumari And Sinee Kumari 2
Fig- 1 Proposed Substrate Integrated Waveguide (SIW) antenna without slot. Fig- 2 The proposed Substrate Integrated Waveguide (SIW) antenna with transverse slot. Dimensions of proposed SIW leaky wave antenna is given in table I. Table I Parameter Value(mm) Parameter Value(mm) a 15 p 2.3 b 1 L 4.55 L1 17 W 0.45 d 1.6 w 10.5 s 0.8 o 4 r 0.8 Sweta Kumari And Sinee Kumari 3
LEAKY-WAVE ANTENNA USING SIW WITH TRANSVERSE SLOT Where a=width of waveguide b=height of waveguide L1=Length of waveguide. s=periodic distance between vias d=diameter of vias p=periodic gap between transverse slots L=Length of transverse slot W=Width of transverse slot w=distance between vias along transverse direction r=relative permittivity of the dielectric medium o=relative permeability of the dielectric medium The proposed model is designed using software HFSS (VERSION 13.0.0.0). The upper and lower rectangular plates are made up of perfect E material. A series of uniform transverse slots are made on the upper plate of the given dimension. The medium between two plates is filled with dielectric material FR4 substrate. Cylindrical vias are made along structure with uniform periodic distance on both side which acts as missing wall for the rectangular waveguide or virtual wall of rectangular waveguide or post wall. Tapering of transverse slots can be done at both ends of waveguide to suppress from the end. [3] SIMULATION AND RESULT: For the proposed design we have studied its performance characteristics like S-parameter, attenuation v/s frequency, phase constant v/s frequency and also the polar plot. 3.1 S-PARAMETER: S-Parameter gives the relation between the incident voltage waves and reflected voltage wave for the various ports of the device. The plot of S11 and S21 are drawn here from simulation on HFSS as these are the important parameters to define the characteristics of the antenna. S11 gives the reflection co-efficient from port 1 when port 2 is considered to be ended in a matched load. For good antenna design S11 should be less than-10 db to ensure that low reflection has occurred from the desired port. Fig-3 shows the variation of S- parameter (S11 and S21) over a frequency range of 5 to 15 GHz. From the simulated result the cutoff frequency of the proposed structure is 9.8 GHz. S21 denotes the transmission co- Sweta Kumari And Sinee Kumari 4
efficient from port 1 to port 2. A higher value of S21 shows that much of the incident wave from port 1 is coupled and transmitted to port 2 which is desirable for a good antenna. In db scale it should have a value near to zero db. Fig-3 (a) also shows the plot of S21 v/s frequencies. Fig- 3 (a) plot of s- parameter v/s frequency Fig-3(b) S Parameter for antenna designed by D.R Jackson, Juhua Liu [21]. The plot of S11 obtained from HFSS simulation of our structure somewhat agrees with the results calculated in [21] as shown by fig-3 (a) and 3(b). The dimension of proposed structure is less than that of structure presented in paper [21]. With such modification the result obtained by us has minimum return loss between 8 to 13 GHz which is our operating frequency whereas the results in 3(b) have minimum return loss at 12 GHz. So we can conclude that by changing the dimension of vias and dielectric material, desired operating frequency can be obtained and minimise the losses. Sweta Kumari And Sinee Kumari 5
LEAKY-WAVE ANTENNA USING SIW WITH TRANSVERSE SLOT 3.2 PHASE CONSTANT: Fig 4-Plot of Phase constant v/s frequency 3.3 ATTENUATION CONSTANT: Fig 5-Plot of attenuation constant v/s frequency 3.4 E AND H FIELD: Since electromagnetic wave is used in the propagation and it consists periodic variation of electric and magnetic field a plot of their magnitude can be a good analysing parameter. The E is plotted on the upper plate of the waveguide Fig-7. The electric field varies sinusoidal along the length of waveguide. The coloured pattern shows the magnitude of field with red colour showing maximum magnitude and blue colour showing minimum magnitude. Magnitude goes on decreasing as colour changes from red to blue as shown in the Fig-7. It can be seen that E and H field do not exist outside the metallic vias as shown by the blue colour (which has almost zero magnitude) so the vias block field from going outside and acts as a wall same as that of rectangular waveguide. Sweta Kumari And Sinee Kumari 6
Fig 6-Proposed SIW leaky wave antenna without slot Fig 7- E field variation along the length of designed SIW The simulated return loss and insertion loss of the proposed antenna without transverse slot is given in Fig-8. It shows that by increasing the diameter of conducting vias the value of return loss decreses. The better result is obtained for d=0.4 Sweta Kumari And Sinee Kumari 7
LEAKY-WAVE ANTENNA USING SIW WITH TRANSVERSE SLOT Fig 8- Plot of S11 and S12 with different diameter The voltage wave standing ratio (VSWR) obtained by the simulation is shown in Fig 9 for different value of diameter. The VSWR must be lie below 2 for good design. It is clear from the Fig-9 the value of VSWR less than 2 for the frequency ranging from 9 GHz to 15GHz. Fig 9- Plot of VSWR v/s frequency The simulated radiation pattern obtained is shown in Fig-10 for different value of azimuthal angle. Fig 10- Plot of radiation pattern with varying of vias The width of SIW shown in Fig-11 is less than the proposed SIW structure in Fig-6 but the obtained return loss is improved. Sweta Kumari And Sinee Kumari 8
[4] CONCLUSION: Fig 11- E-field pattern for TE10 mode In this paper SIW structure is presented as a low-loss/cost, planar structure to alleviate the radiation efficiency degradation caused by traditional planar structure in the high frequency band.the simulation results shows good results such as return loss, insertion loss and gain. REFERENCES: [1]. Dominic Deslandes and Ke Wu, Integrated Microstrip and Rectangular Waveguide in Planar Form, IEEE Microwave And Wireless Components Letters, Vol. 11, No. 2, February 2001. [2]. Y. Cassivi, L. Perregrini, P. Arcioni, M. Bressan, K. Wu, and G. Conciauro, Dispersion Characteristics of Substrate Integrated Rectangular Waveguide IEEE Microwave And Wireless Components Letters, Vol. 12, No. 9, September 2002 [3]. Simon Germain, Dominic Deslandes and Ke Wu, Development Of Substrate Integrated Waveguide Power Divider IEEE CCECE 2003 - CCGEI 2003, Mayimai 2003 [4]. Feng Xu and Ke Wu Numerical Multimode Calibration Technique for Extraction of Complex Propagation Constants of Substrate Integrated Waveguide IEEE 2004 [5]. L. Yan, W. Hong, K. Wu and T.J. Cui Investigations on the propagation characteristics of the substrate integrated waveguide based on the method of lines EE Proc.-Microw. Antennas Propag., Vol. 152, No. 1,February 2005. [6]. Feng Xu and Ke Wu Guided-Wave and Leakage Characteristics of Substrate Integrated Waveguide IEEE Transactions On Microwave Theory And Techniques, Vol. 53, No. 1, January 2005. [7]. Dominic Deslandes and Ke Wu Substrate Integrated Waveguide Leaky-Wave Antenna: Concept and Design Considerations 2005 IEEE. Sweta Kumari And Sinee Kumari 9
LEAKY-WAVE ANTENNA USING SIW WITH TRANSVERSE SLOT [8]. Dominic Deslandes and Ke Wu Accurate Modeling, Wave Mechanisms, and Design Considerations of a Substrate Integrated Waveguide IEEE Transactions on Microwave Theory And Techniques, Vol. 54, No. 6, June 2006. [9]. G.M. Zelinski, G.A. Thiele, M.L. Hastriter, M.J. Havrilla and A.J. Terzuoli Half width leaky wave antennas IET Microw. Antennas Propag., 2007, 1, (2), pp. 341 348. [10]. Maurizio Bozzi, Feng Xu, Dominic Deslandes, Ke Wu Modeling and Design Considerations for Substrate Integrated Waveguide Circuits and Components serbia NIS September 2007 [11]. Junfeng Xu, Wei Hong, Hongjun Tang, Zhenqi Kuai, and Ke Wu Half-Mode Substrate Integrated Waveguide (HMSIW) Leaky-Wave Antenna for Millimeter-Wave Applications, IEEE Antennas And Wireless Propagation Letters, Vol. 7, 2008 [12]. Zhi Xiong Zeng, Wei Hong, Zhi Jun Chen, and Bei Ni Calculation of the Complex Propagation Constant of Substrate Integrated Waveguide 2008 [13]. Yuan Dan Dong and Tatsuo Itoh Composite Right/Left-Handed Substrate Integrated Waveguide Leaky-Wave Antennas,2009 [14]. Qing Hua Lai, Wei Hong, Zhen Qi Kuai, Ying Song Zhang, and Ke Wu, Half-Mode Substrate Integrated Waveguide Transverse Slot Array Antennas, IEEE Transactions On Antennas And Propagation, Vol. 57, No. 4, April 2009 [15]. Giovanni Bozza, Daniele D. Caviglia, and Matteo Pastorino FDTD modeling of a SIW based sensor for THz diagnostics IST 2009 - International Workshop on Imaging Systems and Techniques Shenzhen, China May 11-12, 2009 [16]. Feng Xu, KeWu and Xiupu Zhang Periodic Leaky-Wave Antenna for Millimeter Wave Applications Based on Substrate Integrated Waveguide Vol. 58, No. 2, February 2010 [17]. Masataka Ohira, Amane Miura, and Masazumi Ueba 60-GHz Wideband Substrate-Integrated- Waveguide Slot Array Using Closely Spaced Elements for Planar Multisector Antenna, IEEE Transactions On Antennas And Propagation, Vol. 58, No. 3, March 2010 [18]. Juhua Liu, David R. Jackson and Yunliang Long in Modal Analysis of Dielectric-Filled Rectangular Waveguide With Transverse Slots IEEE Transactions On Antennas And Propagation, Vol. 59, No. 9, September 2011 [19]. Yu Jian Cheng, Wei Hong, KeWu and Yong Fan Millimeter-Wave Substrate Integrated Waveguide Long Slot Leaky-Wave Antennas and Two-Dimensional Multi beam Applications, IEEE Transactions On Antennas And Propagation, Vol. 59, No. 1, January 2011 [20]. Yuandan Dong and Tatsuo Itoh Composite Right/Left-Handed Substrate Integrated Waveguide and Half Mode Substrate Integrated Waveguide Leaky-Wave Structures, Vol. 59, No. 3, March 2011 [21]. Wael M. Abdel-Wahab, and Safieddin Safavi-Naeini Wide-Bandwidth 60-GHz Aperture-Coupled Microstrip Patch Antennas (MPAs) Fed by Substrate Integrated Waveguide (SIW) IEEE antennas and wireless propagation letters, vol. 10, 2011 [22]. Y. J. Cheng Substrate Integratedwaveguide Frequency-Agile Slot Antenna And Its Multibeam Appli- Cation 2012 Sweta Kumari And Sinee Kumari 10
[23]. Juhua Liu, David R. Jackson and Yunliang Long Substrate Integrated Waveguide (SIW) Leaky- Wave Antenna with Transverse Slots IEEE Transactions On Antennas And Propagation, Vol. 60, No. 1, January 2012 [24]. Chang Jiang You, ZhiNingChen, Xiao Wei Zhuand Ke Gong, Single-Layered SIW Post-Loaded Electric Coupling-Enhanced Structure and Its Filter Applications IEEE Transactions On Microwave Theory And Techniques, Vol. 61, No. 1, January 2013 [25]. Zhe Chen, WeiHong, Jixin Chen and Jianyi Zhou Design of High-Q Tunable SIW Resonator and Its Application to Low Phase Noise VCO IEEE Microwave And Wireless Components Letters, Vol. 23, No. 1, January 2013 [26]. Joel D. Barrera,and Gregory H. Huff Analysis of a Variable SIW Resonator Enabled by Dielectric Material Perturbations and Applications IEEE Transactions On Microwave Theory And Techniques, Vol. 61, No. 1, January 2013 Sweta Kumari And Sinee Kumari 11