On the Theoretical Analysis of Radiation Pattern and Gain of Printed Monopole Antennas

Transcription

1 ACES JOURNAL Vol. 3 No. 9 Septembe On the Theoetical Analsis of Radiation Patten and Gain of Pinted Monopole Antennas Somen Bhattachajee 1 Rakhesh S. Kshetimaum and Ratnajit Bhattachajee 1 Depatment of Electonics and Communication Engineeing Techno India Univesit Kolkata India b.somen@iitg.enet.in Depatment of Electonics and Electical Engineeing Indian Institute of Technolog Guwahati India ks@iitg.enet.in atnajit@iitg.enet.in Abstact This pape epots a theoetical appoach to analze adiation patten and gain of Pinted Monopole Antennas (PMA). Theoetical analsis of PMAs is pefomed b modeling PMA as an asmmetical dipole antenna. The effect of patch and gound plane is consideed sepaatel then combined. The fa field epessions fo ectangula and cicula PMAs ae deived and veified with available epeimental esults fom published wok and High Fequenc Stuctue Simulato (HFSS) simulated esults. The analtical simulated and available measued esults ae in close ageement. The theoetical gain fo ectangula and cicula monopole antennas ae also computed and compaed with HFSS simulation esults. is focused on developing analtical appoach to calculate adiation patten and gain of ectangula and cicula PMA taking into account the cuent distibution on the patch as well the effect of the gound plane below the feed line. To the best of the knowledge of the authos theoetical teatment of PMA along with closed fom epessions fo the fa field adiation pattens of ectangula and cicula PMAs has not been epoted in liteatue. The theoetical esults of adiation pattens fo ectangula and cicula PMAs fed b 50Ω micostip line ae compaed with available epeimental data given in [3] and [4] and simulation esults obtained using HFSS. In addition to this the calculated theoetical gain is also veified b HFSS simulation esults. Inde Tems Asmmetical dipole antenna gain Pinted Monopole Antennas (PMA) adiation patten. II. THEORY I. INTRODUCTION Pinted monopole antennas (PMA) ae pominent candidate fo boadband and ulta-wide band applications having featues of lage impedance bandwidth and omnidiectional adiation pattens. Some of the simulation and epeimental woks on PMAs ae available in the liteatue [1]-[5]. Howeve theoetical analsis of adiation chaacteistics of PMAs is not adequatel dealt in the liteatue. Micostip line fed pinted monopole antenna can be consideed as an asmmeticall diven dipole antenna in which the patch and the gound plane fom two ams of the dipole [6]. The spectal domain field components of an infinitesimal cuent souce on an ungounded dielectic lae can be found in [7] but it doesn t account adiation patten and gain calculation. Howeve in [7] numeical appoach is adapted to calculate input impedance and eflection coefficient fo ectangula and F shaped PMA. But the pesent liteatue Submitted On: Apil Accepted On: June A. Radiated field of an HED ling on an ungounded substate The adiated fields of a PMA can be fomulated using Geen s function of an HED ling on an ungounded substate and fom the knowledge of cuent distibution on the patch as well as the gound plane below the feed line. So an HED ling on a lossless and ungounded dielectic lae is consideed fist. To deive spectal domain electic and magnetic field Geen s function an HED is assumed to be ling on a lossless dielectic lae located at ( 0 0 ) shown in Fig. 1. The -diected cuent is defined as J ˆ 0 0 and the effect of J is consideed b appling bounda conditions. The tansvese components of the electic field E and E at ( h) ae given b [7]: ACES E j 0 k k u k0 k J DTE DTM (1)

2 843 ACES JOURNAL Vol. 3 No. 9 Septembe 017 whee E D j TM D 0k k k u DTM k k k D 0 TE J () u u1 u0 tanh u1h 1 u u u tanh u h u u tanh u h TE u u0 1 tanh u 1 h u1 u k k k u k k k z 0 1 z 0 u0 kz k k0 k k k. The fa field adiation patten of an HED on an ungounded dielectic lae in egion z h can be witten as [8]: jk0 e E cos E sin E (3) jk0 e E sin cos E cos cos E. (4) Now substituting Equations (1) () in Equations (3) and (4) k0 sin( ) cos( ) k0 sin( ) sin( ) k0 cos( ) in place of k and we get the final fa field epessions. The fa field adiation patten of an HED on an ungounded dielectic lae is epessed as: E E k k z cos cos tan 1 n jn h 1 n cos j tan 1h n cos n sec j tan 1h n j 1h n (5) sec tan sec 1 whee j 1 cos 4 j sin 4 0 jk0 0 0 e e (6) kn( ) 1 0 n( ) sin. The theoetical gain (G) of an HED on an ungounded dielectic lae in a given diection can be epessed as [9]: 4 sin E cos E G 0 sin E E d jk. (7) It ma be noted that the above Geen s function fo fa field depend on both substate thickness and dielectic constant. Thus the vaiation of thickness and dielectic mateial and thei effects on the field as well as in the gain can be theoeticall obseved. Fig. 1. Geomet of an HED along -ais on the inteface of dielectic and fee space. B. Radiated fields of PMA The above epessions in Equations (5) and (6) give fa fields of a HED on a dielectic substate. The cuent suppoted b the feed in pinted monopole antenna shown in Fig. can be epessed in tems of incident jk0 taveling wave ( ( f e ) g 0 ) and eflected wave ( e jk ( f g ) ) due to impedance discontinuit at the junction of feed and the patch. Note that is the total length of the feed including feed gap f g f g and is the cuent eflection coefficient. Thus the net cuent given to PMA though the feed line can be given b [10]: jk ( fg ) jk ( fg ) J aˆ I ( e e ). (8) Hence L/ W/ jkk. (9) J k k J e dd L/ W/ So afte eplacing k and k b k0 sin( ) cos( ) k0 sin( ) sin( ) and fo 1 Equation (9) can be witten as: J 4sin c 0.5k W sin( )sin (10) 0 1 whee 1 sin 0.5k0 Lsin( )cos cos 0.5k0 L k0cos fgk0 jk0sin( )cos sin fgk0 k L k Lk fgk jk fgk cos 0.5 sin( )cos sin 0.5 sin( )cos cos sin Fig.. Geomet of ectangula pinted monopole antenna on dielectic substate ( 4.3 tan 0.0) of thickness h=1.5 mm in [3]. It ma be noted that cuent distibution in Equation (10) includes a quadatue tem. In case of pinted monopole antennas the gound plane also contibutes

3 BHATTACHARJEE ET AL.: ON THE THEORETICAL ANALYSIS OF RADIATION PATTERN AND GAIN OF PRINTED MONOPOLE ANTENNA S 844 to the adiation field. The gound plane acts as an asmmetic image of the monopole to fom an asmmeticall diven dipole antenna. The cuent distibution in the gound plane can be given as: J 4sin c 0.5k W sin( )sin (11) g 0 g 11 1 whee k sin 0.5k L sin( ) cos cos 0.5k L g g g g k cos 0.5k L sin( )cos sin 0.5k L sin( )cos( ) L g W g epesent the length and width of the gound plane of PMA. Thus the oveall adiation patten fo the ectangula pinted monopole antenna including the effect of the patial gound plane as shown in Fig. can be witten as: j0 jk0 E p e ( J J g ) E 4 (1) j0 jk0 E p e ( J J g ) E 4. (13) The gain fo the case of a ectangula pinted monopole antenna can be calculated using Equation (7). The closed fom epessions fo the fa field adiation pattens of cicula pinted monopole antenna shown in Fig. 3 can be witten as: jk0 e E pc ( J J g ) E (14) jk0 e E pc ( J J g ) E. (15) J can be given as: Fo cicula PMA a J J a a e adad j ka cos( ) kasin( ) cos( ) sin( ) 0 0 whee k k0 sin( ) cos( ) k k0 sin( ) sin( ) and a is the adius of the cicle. Simila to ectangula PMA the gain of cicula pinted monopole antenna can be found using Equation (7). III. RESULTS This section pesents the esults computed using the analtical epessions deived fo the ectangula PMA and cicula PMA and compaes the same with the measued esults available in liteatue as well with the esults obtained though HFSS simulations. The adiation pattens of ectangula pinted monopole antenna ae shown in Fig. 4 and Fig. 5 wheeas the gain plot is shown in Fig. 6. The gain plot shows that the gain is deceasing in the given fequenc band. In othe wods it can be concluded that the antenna is moe diective fo lowe fequencies in compaison to highe fequencies. The adiation pattens of cicula pinted monopole antenna ae shown in Fig. 7 and Fig. 8 wheeas the gain plot is shown in Fig. 9. Fom Fig. 9 it can be obseved that gain is almost constant fo the given band. Fig. 4. Radiation pattens: E-plane and H-plane of the ectangula pinted monopole antenna shown in Fig. at.45 GHz (theo ( ) simulation using HFSS ( ) and measued (.) [3]). Fig. 3. Geomet of cicula pinted monopole antenna on dielectic substate ( 4.7 tan 0.0) of thickness h=1.5 mm in [4].

4 845 ACES JOURNAL Vol. 3 No. 9 Septembe 017 Fig. 5. Radiation pattens: E-plane and H-plane of the ectangula pinted monopole antenna shown in Fig. at 5. GHz (theo ( ) simulation using HFSS ( ) and measued (.) [3]). Fig. 8. Radiation pattens: E-plane and H-plane of the cicula pinted monopole antenna shown in Fig. 3 at 6.5 GHz (theo ( ) simulation using HFSS ( ) and measued (.) [4]). Fig. 6. Gain of ectangula pinted monopole antenna on dielectic substate ( 4.3 tan 0.0) of thickness h=1.5 mm. Fig. 7. Radiation pattens: E-plane and H-plane of the cicula pinted monopole antenna shown in Fig. 3 at 3 GHz (theo ( ) simulation using HFSS ( ) and measued (.) [4]). Fig. 9. Gain of cicula pinted monopole antenna on dielectic substate ( 4.7 tan 0.0) of thickness h=1.5 mm. IV. CONCLUSION In this pape the tansvese field components in spectal domain ae deived fo a hoizontal electic dipole on a lossless dielectic lae which is not backed b a conducting gound plane ae used to calculate the adiation pattens fo ectangula and cicula pinted monopole antenna. Since the gound plane also affects the adiation chaacteistics of PMAs taking the gound plane as an asmmetic image of the monopole the oveall fa field components of PMA ae deived. Howeve the modeling has some limitations because the concept can be implemented fo egula shape of the patch and the gound plane onl. But the theoetical esults in the pesent cases fo the adiation patten ae in

5 BHATTACHARJEE ET AL.: ON THE THEORETICAL ANALYSIS OF RADIATION PATTERN AND GAIN OF PRINTED MONOPOLE ANTENNA S 846 good ageement with HFSS and available epeimental esults. Futhe the theoetical gains of both PMAs ae also veified using HFSS simulations. REFERENCES [1] M. Sifi S. Podilchak M. Essaaidi and Y. Anta Compact disc monopole antennas fo cuent and futue ultawideband (UWB) applications IEEE Tans. Antennas Popagation vol. 59 no. 1 pp Dec [] J. R. Panda and R. S. Kshetimaum An F shaped pinted monopole antenna fo dual-band RFID and WLAN applications Micowave and Optical Technolog Lettes vol. 53 pp Jul 011. [3] M. John J. Evans M. Ammann and J. Modo Reduction of gound plane dependent effects on micostip line fed pinted ectangula monopoles IET Micowave Antennas Popagation vol. no. 1 pp Feb [4] J. Liang C. Chiau X. Chen and C. Paini Stud of a pinted cicula disc monopole antenna fo UWB sstem IEEE Tans. Antennas Popagation vol. 53 no. 11 pp Nov [5] A. Panahi X. Bao G. Ruvio and M. Ammann A pinted tiangula monopole with wideband cicula polaization IEEE Tans. Antennas Popagation vol. 63 no. 1 pp Jan [6] H. J. Visse Appoimate Antenna Analsis fo CAD. John Wile & Sons Ltd 009. [7] S. Bhattachajee R. S. Kshetimaum and R. Bhattachajee Deivation of potential Geen functions fo ungounded dielectic slab and its application in full wave analsis of PMAs Jounal of Electomagnetic Waves and Applications vol. 9 iss. 16 pp [8] D. G. Fang Antenna Theo and Micostip Antenna. CRC Pess 010. [9] D. Jackson and N. Aleopoulos Gain enhancement methods fo pinted cicuit antennas IEEE Tans. Antennas Popagation vol. 33 no. 9 pp Sep [10] A. K. Bhattachaa Long ectangula patch antenna with a single feed IEEE Tans. Antennas Popagation vol. 38 no. 7 pp Jul Somen Bhattachajee eceived his B.Tech. M.Tech. degees in Electonics and Communication Engineeing fom Asansol Engineeing College and NIT Dugapu in 006 and 010 espectivel. He eceived Ph.D. degee fom the Depatment of Electonics and Electical Engineeing IIT Guwahati India in 016. Pesentl he is an Assistant Pofesso in Techno India Univesit Kolkata. His eseach inteests ae in the aeas of antennas micowave and electomagnetic theo. Rakhesh Singh Kshetimaum is a Pofesso in the Depatment of EEE IIT Guwahati. He eceived the Ph.D. degee fom the School of EEE NTU Singapoe in 005. Pio to joining IIT Guwahati he did Postdoctoal eseach fom the Depatment of EE Pennslvania State Univesit USA (005) and the Depatment of ECE IISc Bangaloe ( ). He has chaied seveal IEEE intenational confeences including NCC 016 Guwahati (TPC Chai) DSP 015 Singapoe (Session Chai) AEMC 015 Guwahati (TPC Chai) and WOCN 011 Pais (TPC Chai) NCC 011 Bangaloe (Session Chai) CMC 010 Shenzhen (Publication Chai) and NetCom 009 Chennai (Pogam Chai). He is an Editoial Boad Membe of Intenational Jounal of RF and Micowave Compute- Aided Engineeing (Wile) Aea Edito of AEU Intenational Jounal of Electonics and Communications (Elsevie) Associate Edito of IET Jounal of Engineeing and Edito-in-Chief of Intenational Jounal of Ulta Wideband Communications and Sstems (Indescience). Kshetimaum is the ecipient of IETE M. Rathoe Memoial Awad (015) Dept. of Science & Technolog India (SERC) Fast Tack Scheme fo Young Scientists ( ) and NTU Reseach Scholaship fom His cuent aeas of eseach inteests ae in micowave/millimete wave antennas/cicuits UWB communications & MIMO wieless communications. He is a Life Fellow of the IETE Optical Societ of India Antennas Test & Measuement Societ of India a Senio Membe of IEEE USA Life Membe of Applied Computational Electomagnetics Societ USA and Membe of Euopean Micowave Association. He has published a tetbook and seveal eseach papes in the aeas of his eseach inteests. Ratnajit Bhattachajee eceived his B.E. in Electonics and Telecommunication Engineeing (Fist Class Hons.) fom Gauhati Univesit M.Tech. fom IIT Khaagpu and Ph.D. (Engineeing) fom Jadavpu Univesit Kolkata. Pesentl he is a Pofesso in the Depatment of Electonics and Electical Engineeing IIT Guwahati. Pio to joining IIT Guwahati in 00 he was a Facult Membe in REC (NIT) Silcha. His eseach inteest includes Wieless communication Wieless netwoks Micostip antennas Micowave Engineeing and Electo-

6 847 ACES JOURNAL Vol. 3 No. 9 Septembe 017 magnetics. Seven students have completed thei Ph.D. unde his supevision and at pesent seveal students ae woking unde his supevision. He has co-authoed about one hunded and twent eseach papes in jounals intenational and national confeences. He has seved as Geneal Chai fo 5 th Edition of Applied Electomagnetic Confeence AEMC 015 and nd National Confeence on Communications NCC 016. He has also seved as TPC membe fo seveal confeences. He has developed a web couse on Electomagnetic Theo unde the NPTEL poject of Minist of Human Resouce Development (MHRD). He is also activel involved with the ongoing mission poject of MHRD on vitual laboatoies. He was a Co-investigato fo a contacted eseach fom NICT Japan in the aea of Net-Geneation Wieless Netwoks and PI fo a poject fom ISRO in the aea of development of matched feed fo offset eflecto antennas. Cuentl he is Chief Coodinato fo DeitY suppoted poject fo setting up of an E&ICT academ at IIT Guwahati. He is a Membe of IEEE and Life Membe of Indian Societ of Technical Education.