Study f Diple Antenna Height fr Radi Telescpe Accrding t Baghdad Lcatin Kamal M. Abd 1, Mretadha J. Kadhim and Zinah F. Kadhim 3 1 Department f Astrnmy and Space, Cllege f Science, University f Baghdad, Baghdad, Iraq. Electric Engineering Department, Cllege f Engineering, University f Baghdad, Baghdad, Iraq. 3 Department f Astrnmy and Space, Cllege f Science, University f Baghdad, Baghdad, Iraq. ABSTRACT Diple with ne element and tw-elements arrays antenna have been built in rder t detect 0.1 MHZ radi emissin frm Jupiter and I (Jupiter's satellite). The Jupiter elevatin angle at Baghdad lcatin (44.45, 33.35) fr a perid f fifteen year (005-00) has achieved frm Radi Jve pr..the radiatin pattern fr diple antenna (with ne and tw elements) at different height abve grund (5ft t 30ft) are calculate frm EZNEC+ 5.0 package with its maximum gain. A cmparisn between the results fr Jupiter elevatin angle curve and pattern angle which gives maximum gain at different height can be cnclude suitable result fr best antenna height t ensure height prbability fr detectin Jupiter radi emissin and I. Keywrds: Diple antenna, Radi signal, Linear wire antenna, Grund plane. 1. INTRODUCTION An antenna diple is a device that prvides means fr radiating r emitting radi waves. It is cnsidered t prvide transmissin f guided waves n transmissin line t free space [1]. In ther wrds the antenna diple is the transmissin unit between free-space and guiding device. The guiding device r transmissin line may take the frm f caxial line r hllw pipe (waveguide), and it is used t transprt electrmagnetic energy frm the transmitting surce t the antenna r frm the antenna t the receiver []. The antenna is cnsidered as a detectr used fr cllecting the radiatin [3].. DIPOLE ANTENNA TYPE There are many type f diple antenna which is the simplest and imprtant type f linear wire antenna:.1. Half wavelength diple Avery widely used antenna is the half-wave diple antenna.it is a linear current whse amplitude varies as ne-half f sine wave with maximum at the center. Als it culd be imagined t flw n an infinitely thin, perfectly cnducting, half-wavelength lng wire [4]... Shrt-wave diple The current n a straight wire antenna must smthly g t zer at the wire ends. The current distributin n a center fed wire diple f length Z called a shrt diple is apprximately triangular in shape because the current distributin n thin wire antenna diameter ) is apprximately sinusidal and als must be zer at the wire ends []..3. Ideal diple The ideal diple has a unifrm current in reality alng all wire, that is n drp dwn in the end f wire []. 3. FUNDAMENTAL ANTENNA PARAMETERS 3.1 Radiatin Pattern Radiatin pattern (r antenna pattern) is graphical representatin f the radiatin prperties f an antenna [5]. It is define as mathematical functin r graphical representatin f the radiatin prperties as functins f space crdinates. In mst cases the radiatin pattern is determined in the far-field regin (space crdinates) and is represented as a functin f the directinal crdinates []. Radiatin pattern prvides a descriptin f the angular variatin f radiatin level arund an antenna, which is prvides a ne f the mst imprtant characteristic f an antenna [5] Vlume 3, Issue 9, September 014 Page 90
as illustrate in figure (1). Figure 1: Three-dimensinal pattern f a λ/ [] 4. DIRECTIVITY The directivity f an antenna is defined as the rati f the radiatin intensity in a given directin frm the antenna t the radiatin intensity averaged ver all directins [6]. The average radiatin intensity is equal t the ttal pwer radiated by the antenna divided by 4π. As given by the equatin: U 4U D U P rad (1) Where U = radiatin intensity (W/unit slid angle), U = radiatin intensity f istrpic surce, pwer []. P rad the ttal radiated 5. EFFICIENCY The antenna efficiency takes int cnsideratin the hmic lsses f the antenna thrugh the dielectric material and the reflective lsses at the input terminals [7]. 6. GAIN The antenna gain measurement is linearly related t the directivity measurement thrugh the antenna radiatin efficiency. The antenna abslute gain is the rati f the intensity, in a given directin, t the radiatin intensity that wuld be btained if the pwer accepted by the antenna were radiated istrpically [8] [9]. Antenna gain is: G e rad U (, ) D 4 P where erad is the radiatin efficiency, P in pwer input. in () 7. WIRE ANTENNA ABOVE AN IMPERFECT GROUND PLANE The peratin f lw frequency (rughly VHF and belw) antenna is affected significantly by the presence f typical envirnmental surrundings, Such as the earth buildings, and s frth. A perfect grund plane in its ideal frm is an infinite plane, perfect cnductr it is well apprximated in practice by a planar gd cnductr that is large relative t the antenna extent. If the grund planes that are nt well apprximated by a perfect grund plane. Since lw-frequency antenna is mst affected by their surrundings and lw-frequency antenna are usually wire antenna, the illustratins will be fr wire antennas abve grund plane.the general principles can hwever be applied t many antenna type []. 8. WORKS AND RESULTS Our wrk is based n get the elevatin angle f Jupiter and it's satellite I fr a fifteen years (005-00) at Baghdad lcatin frm Radi Jve pr.. Diple with ne and tw elements are designed at different heights (5 t 30) feet s as t receives the same signal frm Jupiter and its satellite. Then a cmparisn have been made between the elevatin angle f Jupiter and it's I satellite with the radiatin pattern f diple (ne and tw elements) s as t get suitable height and time fr diple t detect the radi signal frm Jupiter and it's satellite I as shwn in figure. Vlume 3, Issue 9, September 014 Page 91
Evaluate elevatin angle f Jupiter and it's I satellite using Radi Jve pr. Design diple using EZNEC+ 5.0 package Diple with ne element fr height (5-30) Diple with tw elements fr height (5-30) Cmparisn f elevatin angle f Jupiter and it's satellite I with the pattern angle frm diple with ne and tw elements 8.1 Single Diple Antenna near the Grund Figure : Flwchart f the wrk. This type f antenna was designed using EZNEC+ 5.0 package. The height f this type f diple has been tken frm (5 t 30) feet. The maximum gain at different heights (5 t 30) feet fr this diple type is achieved. The figure (3a) represents antenna maximum gain with different antenna heights, where the value f maximum gain has been increasing with increase the height f diple. In figure (3b) the value f pattern angle f Jupiter has been pltted with the heights. The value f pattern angle is decreasing with the heights (frm 90 deg. t reach 3 deg.). Figure 3: Antenna height and maximum gain fr diple with ne element near the grund. Antenna height and pattern angle fr diple with ne element near grund. 8. Diple with tw Elements T achieves twice the gain (signal amplificatin) f single diple and als allws steering the antenna beam t desired regin f the sky twards Jupiter lcatin fr maximum gain and t increase the efficiency f diple. Diple with tw elements has been designed using EZNEC+ 5.0 package. Dual diple array is the same wavelength (0.1MHz) as diple with ne element s here cnsider tw diples placed at distance 0ft apart frm each ther bth at height (h) frm the grund and with phase difference angle between them equal (5 ). In figure (4a) the value f maximum gain is increasing nticeably with heights. While in figure (4b) explain that the decreasing f pattern angle f this type f diple is smthly starting by angles (54 deg. t reach 3 deg.) with the heights. Vlume 3, Issue 9, September 014 Page 9
Figure 4: Antenna height and maximum gain fr diple with tw elements. Antenna height and pattern angle fr diple with tw elements. 9. COMPARISON BETWEEN TWO DIPOLES NEAR THE GROUND Figure (5a) shws the cmparisn between value f maximum gain fr diple with ne element and tw elements near the grund with heights which shw the increase f maximum gain fr diple with tw elements. Figure (5b) explains cmparisn between pattern angles f diple with ne element and diple with tw elements near the grund with heights. They ntice that pattern angle decreasing smthly with heights when cmpared with the pattern angle fr diple with ne element. Figure 5: Cmparisn between maximum gain and heights fr diple with ne and tw elements near the grund. Cmparisn between pattern angle and heights fr diple with ne and tw elements near the grund. 10. A COMPARISON BETWEEN THE JUPITER ELEVATION ANGLE AND ANTENNA PATTERN ANGLE The result f pattern angle btained frm EZNEC+ 5.0 package fr diple with ne element has been cmpare with the elevatin angle f Jupiter and it's satellite I results frm Radi Jve pr.. When cmpare the elevatin angle f Jupiter and it's satellite I, we fund that sme f the elevatin angle is missing fr the perid (005 t 00) years. The missing elevatin angles are in years (01, 013, 014, and 015), where we can't fund the exact pattern angle that match the elevatin angle. Suitable height and year that can be used t bserve Jupiter and it's satellite I using diple antenna with ne element fr the perid (005-00) explain in table (1). Vlume 3, Issue 9, September 014 Page 93
Table 1: Suitable height and year fr diple with ne element Jupiter elevatin angle [deg] Jupiter elevatin angle [deg] Table 1: (cntinued) Year Height f antenna [ft] 31 018 9 019, 00 3 In diple with tw elements we fund the same prblem as in the previus diple. The missing elevatin angle in years ( 01, 013, 014, and 015) are nt fund in this type f diple because Jupiter sme years spent mre time abve the hrizn (apprximately 13 hurs ) cmpare with the ther time. Practically fund this type f diple is mre efficiency than the diple with ne element. Suitable height and year that can be used t bserve Jupiter and it's satellite I using diple antenna with ne element fr the perid (005-00) explain in table (). Table : Suitable height and year fr diple with tw elements Jupiter elevatin angle [deg] Year Hight f antenna [ft] Height f antenna [ft] 64 011 11, 13 58 015, 016 1 47 010, 017 15 44 017 16 41 006, 009 17 39 006, 009, 017 18 36 006, 018 19 34 007, 008, 018 0 3 018 1 Year 54 5,6 005, 010, 011 53 7 010, 016 5 8 005, 010 51 9 005 50 10 005 48 11 005, 016 47 1 017 45 13 005, 010, 017 43 14 005, 006, 009 41 15 006, 009 40 16 006, 009 38 17 006 37 18 018, 017 35 19 007, 008, 009, 018 33 0 007, 008, 009 3 1 018 31 018 9 3 019 8 4 00 7 5 019, 00 Vlume 3, Issue 9, September 014 Page 94
11. Matlab Prgramming fr Radiatin Pattern Equatins The MATLAB language has been used t build prgram in rder t draw and explain the main prperties f radiatin pattern f this diple antenna where the first type f diple used t draw the radiatin pattern is a diple with ne element near the grund and the ther is tw elements near the grund. The length f a diple antenna using infinitely thin wires is exactly half a wavelength ( /). Much like an rgan pipe is cut t a specific length t make it resnant fr a particular frequency f sund, ur diple antenna is cut t a length f half a wavelength t make it resnant at the frequency f 0.1 MHz. One Element Diple near the Grund Nw accrding t diple with ne element near the grund [] cs ( cs ) Z I h (3) U1 sin sin cs sin d Where Z is the impedance f wire, I is the input current, h here is represent height f antenna and d is the ttal length f a diple. and is represented as : is elevatin angle which is taken frm 0 t,φ is the azimuth angle which is taken frm 0 t Tw Elements Diple near the Grund A prgram has been built in MATLAB is a diple with tw element near the grund where this cnfiguratin achieves twice the gain (signal amplificatin) f a single diple. Then the equatin fr the tw element near the grund is [ ] cs ( cs ) Z I h b (4) U sin sin cs cs sin cs sin d d where Z, I,h,, are explain abve is a phase different between the tw diples b is the spacing between them Then in all t abve we calculate the pwer radiatin which is given by the equatin [] P 4U sin (5) Where = 3.14 r (/7) U is the radiatin intensity as explain abve and t fund the directivity by the equatin [] D U / P (6) Where P. the ttal pwer ver all pattern Finally draw the result.after cnvert t db unite using this equatin []: db 10lg 10 D (7) 1. Result Cmparisn fr Antenna Radiatin Pattern between the Matlab and EZNCE+ 5.0 Package The result t previus cmpared data in table (1) f diple with ne element near the grund funded that there are sme height f antenna are appear suitable fr sme year s as radiatin pattern has been pltted t this height fr example. Maximum gain results frm Matlab language and EZNCE+ 5.0 package. Results are listed in table (3) and shw in figure (6) fr Matlab language and figure (7) fr EZNCE+ 5.0 package. Table 3: Maximum gain and height fr diple with ne element near the grund 4. Vlume 3, Issue 9, September 014 Page 95
(c) (d) Figure 6: Radiatin pattern f diple with ne element near the grund using Matlab language with height 1 ft 18 ft (c) 0 ft (d) 3 ft (c) (d) Vlume 3, Issue 9, September 014 Page 96
Figure 7: Radiatin pattern f diple with ne element near the grund using EZNCE+ 5.0 package with height 1 ft 18 ft (c) 0 ft (d) 3 ft Fr diple with tw elements near the grund the suitable height which is result frm table () with the maximum gain result frm Matlab language and EZNCE+ 5.0 package are list in table (4), and shws in figure (8) fr Matlab language and figure (9) fr EZNCE+ 5.0 package. Table 4: Maximum gain and height fr diple with tw elements near the grund. (c) (d) Figure 8: Radiatin pattern f diple with tw elements near the grund using Matlab language with height 5 ft 13 ft (c) 14 ft (d) 19 ft Vlume 3, Issue 9, September 014 Page 97
(c) (d) Figure 9: Radiatin pattern f diple with tw elements near the grund using EZNCE+ 5.0 package with height 5 ft 13 ft (c) 14 ft (d) 19 ft 13. CONCLUSION Diple with ne and tw elements can't detect all elevatin angle f Jupiter and it's satellite I fr the perid (005-00) years. The value f the maximum gain is increasing with increase the number f elements in diple near the grund frm ne element t tw elements and its als increasing with increasing heights f diple. The value f efficiency is increasing als with the increase the number f elements. Values f pattern angle decreasing smthly with diple f tw elements as cmparable t diple with ne element. This makes diple with tw elements mre practical than diple with ne element. REFRENECES [1] 1-Jhn W., and Sns I. Antenna thery and, design United states f America, 003. [] -Cnstantine A., Antenna thery analysis and, design 3 th editin, New Jersey, Canada, 005. [3] Rth G., "Handbk f Practical Astrnmy", Berlin Heidelberg, 009. [4] 4-Wen F., and Hsueh-Jyh L., Spatial crrelatin f half-wavelength diple arrays using spherical mde, expansin IEEE 0 th internatinal Sympsium n persnal, pp. 1074-1077, 009. [5] 5-Dng J., Wang A., and Lan H., A Simple Radiatin Pattern Recnfigurable Printed Diple, Antenna schl f Electrnic and infrmatin Engineering, Tianjin University IEEE, vl. 7, 009. [6] 6-Rbert J., and Maillux, Pased Array Antenna, Handbk Artech Huse antenna and prpagatin library, 005. [7] 7-Kim K., and Yang s., Efficiency f resistive vee diple antenna, Electrnic Letters ISSN:00135194, vl. 43, 007. [8] 8-Ali M.T., Rahman T. B. A., Kamarudin M. R. B., Tan M. N. M., and Sauleau R., Planar Array Antenna with parasitic Elements fr beam Steering, Cntrl in prceeding f prgress in Electrmagnaetics Research Sympsium, Mscw RUSSIA, pp. 181-185, August, 009. [9] 9- Chang D.C., and Huang M.C., Micrstrip reflectarray antenna with ffset, feed Electrn.Lett., vl.8, n.16, pp.1489-1491, July, 199. Vlume 3, Issue 9, September 014 Page 98