Joural of Electromagetic Aalysis ad Applicatios, 2011, 3, 242-247 doi:10.4236/jemaa.2011.36039 Published Olie Jue 2011 (http://www.scirp.org/joural/jemaa) History ad Advacemet of the Family of Log Periodic Toothed Plaer Microstrip Atea Arti Vaish, Aita Dalal Faculty of Egieerig ad Techology, Maav Racha Iteratioal Uiversity, Faridabad, Idia. Email: vaisharti@gmail.com Received April 8 th, 2011; revised May 10 th, 2011; accepted May 19 th, 2011. ABSTRACT This paper presets the family of logarithmically periodic toothed plaer ateas. I this the dimesios of the successive sectios were icreased i geometric progressio for a wide badwidth usage. A bad width of 7% for trapezoid toothed, 26% for zigzag toothed ad 50% for cross-toothed VSWR < 2 has bee obtaied from the proposed ateas. Ivestigatios o the gai ad radiatio characteristics have bee carried out. The ivestigatios show that the proposed desigs ot oly offers the ehaced badwidth but also possesses the same characteristics over the desired frequecy bad at same probe feed positio. Keywords: Log Periodic Atea, Probe Feed, Wide Bad Atea, Improved Badwidth 1. Itroductio Researches o ew types of broadbad logarithmically periodic ateas structures are studied. The Log-Periodic Atea (LPA) is ivestigated as a ew type of atea, whose properties vary periodically with the logarithm of frequecy, ad provides wide badwidth, broad beam width, ad high gai. This atea has smaller trasverse dimesios tha aother atea types. The ateas have patter ad impedace characteristics which are essetially idepedet of frequecy over theoretically ulimited badwidths. Data trasmissio at higher rates requires wider badwidths for the elemets costitutig a commuicatio lik. This required widebad ateas be desiged ad used [1,2]. I logarithmically periodic atea [3], the electrical properties vary with log of operatio frequecy. The high frequecy atea described by Duhamel ad Berry [5,6] was periodic structure i which the dimesio of successive sectios was icreased i geometric progressio. The log periodic toothed trapezoidal atea (LPTTA) ca be slightly modified to obtai a refied geometry referred to log periodic zigzag ad cross toothed ateas. The differet (log periodic toothed ateas) are also specified by agle i a maer similar to the LPTTA described earlier [7-10]. The importat feature of these ateas is that they represet a earlier lik to the developmet of log-periodic dipole The iitial desig based o the cocept of log periodic structure was the log periodic toothed plaar atea followig the agle cocept, if oe tooth has width, the ext smaller oe is 2 wide, third is ad so o. Let the width of the widest be sigma1, which is approximately oe quarter wavelegth correspodig to the lower frequecy limit. The the widest of th tooth, sigma (1) 1 where is a costat represetig the geometric ratio of width ( + 1). The tooth s to width of th tooth. Takig log o both sides log log log (2) For a give atea log 1 ad log are costat. Cosequetly the log of icreases i equal steps with. That is, log icreases periodically, hece the ame log periodic. It is also implied that whatever the electrical properties the atea may have at a frequecy f 0, will be repeated at frequecy give by * f 0 (3) 2. Atea Desig The proposed cofiguratio of ateas alog with the same positio of the probe feed at origi (0, 0) is show i Figures 1, 2 ad 3. The desig of log periodic toothed ateas [11-17] depeds upo various parameters such as geometric ratio (τ), tooth width (σ) ad agles α, β (alpha, beta). Here we have take the highest frequecy 1
History ad Advacemet of the Family of Log Periodic Toothed Plaer Microstrip Atea 243 Figure 1. The proposed cofiguratio of trapezoidal toothed Figure 2. The proposed cofiguratio of cross toothed 18 GHz. We have take frequecy rage 2 GHz to 18 GHz. Desig for 7 Cells of the Atea If we take the 1 st cell to be equal to λ/2 the R6 = 9.8 mm r5 = 10.621 mm R5 = 11.52 mm r4 = 12.50 mm R4 = 13.56 mm r3 = 14.705 mm R3 = 15.95 mm r2 = 17.30 mm R2 = 18.77 mm r1 = 20.35 mm R1 = 22.08 mm Takig τ = 0.85 with α = 60 ad β = 20 Dielectric costat (ε) = 4.4 Loss taget = 0.0002 Z-top = 1.6 3. Result ad Discussio The proposed atea has bee aalyzed usig IE3D Software usig probe feed at (0, 0) [20]. Figures 4, 5 ad 6 shows the variatios of VSWR with frequecy for LPTA for trapezoidal, cross ad zigzag geometry. For trapezoidal toothed atea as we ca see from Figure 4 that for frequecy 13.0295 GHz to 13.9 GHz the iput VSWR is lesser tha two (VSWR < 2). This is the usable rage of the atea, i.e. 7% of badwidth is available. For cross toothed atea as observed from Figure 5 that for frequecy 11.025 GHz to 13.9 GHz the iput VSWR is lesser tha two (VSWR < 2). This is usable rage of the atea, i.e. 26% of badwidth is available ad for zigzag toothed atea as observed from Figure 6 that for frequecy 10.5 GHz to 16.3 GHz the iput VSWR is lesser tha two (VSWR < 2). This is the most useful rage of the atea, i.e. 50% of badwidth is available. With the aalysis of the atea badwidth it is observed that badwidth is improved for the geometry of Figures 2 ad 3 as compare to Figure 1. Similarly from the gai versus frequecy plot i Figures 7, 8 ad 9 of the trape- Figure 3. The proposed cofiguratio of zigzag toothed Figure 4. Plot of VSWR versus frequecy of trapezoidal
244 History ad Advacemet of the Family of Log Periodic Toothed Plaer Microstrip Atea Figure 5. Plot of VSWR versus frequecy of cross Figure 8. Plot of gai versus frequecy for cross toothed Figure 6. Plot of VSWR versus frequecy of cross Figure 9. Plot of gai versus frequecy for zigzag toothed Figure 7. Plot of gai versus frequecy. Figure 10. 3D Radiatio patter of trapezoid toothed
History ad Advacemet of the Family of Log Periodic Toothed Plaer Microstrip Atea 245 Figure 11. 3D Radiatio patter of cross toothed Figure 12. 3D Radiatio patter of zigzag toothed Figure 13. Smith Chart of trapezoidal toothed
246 History ad Advacemet of the Family of Log Periodic Toothed Plaer Microstrip Atea Figure 14. Smith Chart of cross toothed Figure 15. Smith Chart of zigzag toothed
History ad Advacemet of the Family of Log Periodic Toothed Plaer Microstrip Atea 247 zoidal, cross ad zigzag patter it is observed that the maximum gai is obtaied for the zigzag geometry so we ca practically implemet the zigzag patter ad optimize it for the better results for a wide bad usage. The 3D Radiatio patter ad smith chart of the proposed trapezoid, cross ad zigzag atea are show i Figures 10, 11, 12,13, 14 ad 15. 4. Coclusios A log periodic self complemetary toothed plaer probe feed ateas have bee proposed. Log periodic zigzag toothed atea ad Log periodic crossed toothed atea have better results as compare to the basic geometry as show i Figure 1. The proposed desigs have ehaced badwidth, gai, radiatio patter ad VSWR ad similar characteristics throughout the operatig badwidth. 5. Ackowledgemets The author thakfully ackowledges the authorities of Maav Racha Iteratioal Uiversity, Faridabad, Haryaa, for the provisio of facility for this research work. REFERENCES [1] C. A. Balai, Atea Theory, Atea Theory, Wiley, New York, 2007. [2] R. C. A. DuHamel, H. Balai ad D. E. Isbell, Broadbad Loga Rithmically Periodic Atea Structures, IRE Natioal Covetio Record, May 1957, pp. 119-128. [3] C. A. Balai, Atea Theory: Aalysis ad Desig, 2d Editio, Joh Wiley ad Sos, New York, 1997. [4] C. E. Smith, Log Periodic Atea Desig Hadbook, 1st Editio, Ohio, 1966. [5] R. H. DuHamel ad E. G. Berry, Logarithmically Periodic Atea Arrays, IRE Wesco Covetio Record, August 1958, pp.161-177. doi:10.1109/wescon.1958.1150224 [6] R. H. DuHamel ad F. R. Ore, Logarithmically Periodic Atea Desig, IRE Natioal Covetio Record, 1958, pp. 139-152. [7] V. H. Rumsey, Frequecy Idepedet Ateas, IRE Natioal Covetio Record, March 1957, pp. 114-118. doi:10.1109/irecon.1957.1150565 [8] R. L. Carrel, The Desig of Log-Periodic Dipole Ateas, IRE Natioal Covetio Record, March 1961, pp. 61-75. doi:10.1109/irecon.1961.1151016 [9] W. L. Stutzma ad G. A. Thiele, Atea Theory ad Desig, 2d Editio, Joh Wiley ad Sos, New York, 1998. [10] V. H. Rumsey, Frequecy Idepedet Ateas, Academic Press, New York, 1996. [11] R. S. Elliott, A View of Frequecy Idepedet Ateas, The Microwave Joural, Vol. 5, December 1962, pp. 61-68. [12] Y. Mushiake, Self-Complemetary Ateas, Spriger- Verlag, Berli, 1996. [13] R. L. Carrel, The Desig of Log-Periodic Dipole Ateas, IRE Natioal Covetio Record, 1961, pp. 61-75. [14] W. L. Stutzma ad G. A. Thiele, Atea Theory ad Desig, 2d Editio, Joh Wiley ad Sos, New York, 1998. [15] D. F. Di Fozo, Reduced Size Log Periodic Ateas, The Microwave Joural, Vol. 7, December 1964, pp. 37-42. [16] M. D. Sigh, S. P. Kosta ad A. Sigh, Log Periodic Atea with Loop Elemets, Iteratioal Joural of Electroics, Vol. 32, No. 1, 1972, pp. 81-84. doi:10.1080/00207217208938272 [17] D. Sharma ad R. Kumar, Desig ad Aalysis of Five Elemet Microstrip Log-Periodic Atea, Iteratioal Coferece o Applicatios of Electromagetism ad Studet Iovatio Competitio Awards, Taipei, 11-13 August 2010, pp. 210-214. [18] D. Varo ad R. B. Kieburtz, Theoretical Aalysis of a Log Periodic Structure, Ateas ad Propagatio Society Iteratioal Symposium, 21-24 September 1964, pp. 58-61. doi:10.1109/aps.1964.1150143. [19] O. Ergui ad L. Gruel, Circular Arrays of Log Periodic Ateas for Broadbad Applicatios, Proceedigs of the Europea Coferece o Ateas ad Propagatio, Nice, 6-10 November 2006, p. 503. [20] IE3D Software Release 8 Developed by m/s Zealad software Ic.