Multiband Microstrip Patch Antenna for Microwave Applications

Transcription

1 IOSR Jounal of Electonics and Communication Engineeing (IOSR-JECE) ISSN: , ISBN: Volume 3, Issue 5 (Sep. - Oct. 2012), PP Multiband Micostip Patch Antenna fo Micowave Applications Syed Ahsan Ali 1, Umai Rafique 2, Umai Ahmad 3, M. Aif Khan 4 1,2,3,4 Depatment of Electonic Engineeing, Mohammad Ali Jinnah Univesity, Pakistan Abstact: In this pape, we pesent a factal shape slot based patch antenna fo multiband opeations. The factal shape slot is designed on the ectangula patch and the antenna is fed though a micostip line. The poposed design and feeding technique allows the antenna to opeate at multiple fequencies in the ange of 1-20 GHz. It is demonstated though simulation that the Retun Loss (RL) values occued at 1.33 GHz, 4.16 GHz, 7 GHz, 9.8 GHz, 12.7 GHz, 15.5 GHz and 18.3 GHz, espectively, having VSWR 2. It is also obseved that the gain of poposed design is highe than the conventional patch antenna. Paametic study is also included to give an oveview fo the pefomance of poposed design. Keywods: factal shape, patch antenna, multiband opeations, micostip line, paametic study. I. Intoduction Inceasing pogess in communication system inceases the demand of compact, cost ective and easily fabicated antennas. So, this equiement of pesent time is full-filled by the invention of patch antenna [1]. They ae light weight, affodable, easy to manufactue and can easily be used in hand-held devices. Micostip patch antenna is a metallic plate mounted on a dielectic of any kind. Mostly, low dielectic constant and thicke mateial is used fo the designing of patch antenna. The patch has diffeent shapes like cicula, ectangula, ing and elliptical, espectively. Anothe metallic plate is mounted at the bottom of dielectic which is known as gound plane. Gound plane povides sufficient eflections to the finging fields which occued due to the change in length of patch antenna. Micostip patch antenna can be fed by vaious techniques which ae pobe feed, micostip line feed, poximity coupled feed and apetue/slot-coupled feed. Among all the advantages, thee ae few dawbacks of using patch antenna which ae low gain, naow bandwidth, high ohmic losses and low iciency. Reseaches poposed many techniques to ovecome these disadvantages, but thee is always a tade-off between the pefomance and design. Recently, multiband patch antennas ae investigated because of coveage of many wieless communication sevices such as GSM, DCS, CDMA and PCS [2, 3]. Many conventional techniques such as the use of PIN diodes, switches and vaacto diodes ae used fo multiband opeation [4, 5 & 6]. But, these designs povide econfiguable fequency opeations with bi-state ON/OFF contol. Also, the use of active components inceases complexity in the design and thei use ae difficult to handle because it needs exta biasing netwok. In [7], multiband chaacteistics wee achieved though a tiangula patch which opeates in the ange of GHz. In this case, chip capacitos ae used instead of vaacto diodes. The impedance of an antenna is also contolled though chip capacitos which is a modeate technique. In [8], a patch antenna was designed with a U-slot and by using PIN diodes. The PIN diodes ae used to switch the slots ON and OFF fo diffeent fequency bands. But, it povides ti-band esponse in the epoted fequency ange. Anothe patch antenna was designed by incopoating two slots on both sides of the patch which ae contolled by two switches. The status of these two switches changes the esonant fequencies which affects the fequency bands. In [9], a micostip patch antenna was pesented fo wieless applications which woks fom 0.9 GHz to 5.35 GHz. A multiband esponse was achieved by designing a modified gound plane. It has a unique stuctue of comb shape on both sides of the patch. This technique also helps to enhance the bandwidth and gain of an antenna. A wideband micostip patch antenna which also allowed multiband popeties by designing an aay was pesented in [10]. This technique gives bette iciency and gain, opeating at diffeent bands which ae 2.4 GHz, 5.5 GHz and 9 GHz, espectively. Accoding to the pesented esults, it includes two satellite communication bands which ae C and X-band. These bands ae also widely used in cellula communication, WLAN and ada communication. To educe the ective pemittivity of substate, a technique of Photonic Band-Gap (PBG) stuctue was intoduced in [11]. The poposed multiband patch antenna esonates at six fequency bands in the ange of GHz. These bands cove most of the commecial communication applications. The designing of PBG stuctue on gound plane disgade the iciency of an antenna. Multiple patches with a slot-coupled technique wee also used to get multiband esults [12]. Thee patches wee used and a slot was etched in the middle of patch to couple uppe and lowe patches. This design woked at diffeent bands in fequency ange GHz. It coves GPS, PCS and GSM fequency bands. In this pape, a factal shaped slot based micostip patch antenna is designed and pesented fo multiple fequency opeations. The poposed antenna design is able to opeate in the fequency ange of Page

2 GHz having seven opeating esonant fequencies which cove most of the desied communication bands. In addition, a VSWR which is 2 is achieved accoding to the 10 db bandwidth citeia. Also, the gain of an antenna is not achieved accoding to the citeia fo lowe fequency bands, but the gain achieved fo uppe fequencies is much highe than the conventional patch antenna. II. Antenna Geomety And Design The design and geomety of poposed antenna and factal shape slot is shown in Fig.1. The antenna geomety consists of two dielectic layes in which the ectangula patch is designed on the uppe substate. The ectangula patch consists of a factal shape slot which allows the antenna to adiate at multiple fequencies. The wod factal means that ecusively geneated stuctue having diffeent dimensions. The dielectic used fo the design pupose is Roges RT/Duoid 5870 having elative pemittivity 2.33 and thickness 1.57 mm, espectively. The ectangula patch dimensions can be calculated as: whee 1 L 2L 2 f o o (1) and whee 1 1 h (2) W L h W 0.3 h 1 2 W vo 2 W 2 f h (3) (4) Hence, W is the width of the patch, L is the length of the patch, ε is the ective dielectic constant of the mateial, v o is the speed of light in a vacuum, f is the taget fequency, ε is the dielectic constant of the substate, h is the thickness of the substate and ΔL epesents the extension in length caused by the finging ect and by consideing the dimension of the patch, it can confomably be ignoed. The gound plane is sandwiched between the two dielectic layes. This technique is taken fom the slot-coupled feed method of micostip patch antenna design, because the placement of gound plane between the dielectic layes minimizes intefeence between adiating element and feed. By using this technique, an ective antenna stuctue can be obtained and maximum iciency can be achieved. The above pesented geomety is then designed by using Ansoft HFSS. The oveall dimensions of the ectangula patch and factal shape slot is taken to demonstate the antenna pefomance. The oveall dimensions of the slot ae shown in Fig. 1 (b) and the values accoding to the dimensions ae given in Table Page

3 (a) Fig. 1: (a) Geomety of poposed antenna and (b) dimensions of factal shape slot within a patch. (b) III. Results And Discussion This section descibes the simulation esults of poposed multiband micostip patch antenna. Discussion on the esults is also povided in this section. Fig. 2 shows the simulated input etun loss of poposed antenna. It is noticed that seven esonant fequencies occued in the ange of 1-20 GHz which ae 1.33 GHz, 4.16 GHz, 7 GHz, 9.8 GHz, 12.7 GHz, 15.5 GHz and 18.3 GHz, espectively. The esonant fequencies obseved accoding to the 10 db bandwidth citeia. The poposed factal shape slot can be vey useful to obtain a multiband esponse which is clea fom Fig. 2. Also, VSWR noted at the esonant fequencies is 2 which is the second majo esult of antenna design. The VSWR coesponding to the input etun loss is shown in Fig. 3. One of the most and majo design paamete is the impedance matching of an antenna. In the poposed design, the impedance matching is achieved by applying 50Ω input impedance to the micostip line and by adjusting the width of feed line. A paametic study is obtained by changing the some slot dimensions and thickness of dielectic to demonstate the pefomance of poposed design. Fig. 4 and 5 shows the simulated gain of poposed antenna. Fom Fig. 4, it is noticed that the poposed design is also compatible fo eceiving antenna system in the ange of 1-10 GHz, because most of the fequency bands giving negative gain which is useful at eceive side. The maximum gain noted fo lowe fequency bands is 9 dbi in the ange of GHz, while minimum gain is -7dBi. Fig. 5 demonstated that the poposed design is much suitable fo satellite communication. As the fequency inceases, gain is also inceases. It can also be said that the gain is completely obeying the ule of input etun loss fo highe fequency bands. As the etun loss appoaches to zeo, gain will incease with espect to it. The aveage gain noted fo highe fequency bands is 5 dbi. 45 Page

4 Fig. 6 shows the simulated input etun loss by changing the slot length l 1. When the length is adjusted lowe than the actual length which is shown in Fig. 1 (a), thee is no change obseved in the etun loss, but when the length is taken highe than the actual length, the impedance mismatch occued at the most lowe fequencies. Thee is not change obseved at the highe fequencies. Also, the VSWR is also changed accoding to the etun loss. Fig. 7 shows the simulated input etun loss by changing the slot length l 2. When the length is adjusted lowe than the actual length and all othe paametes ae kept constant, thee is no ect in the etun loss obseved. But, when the length is chosen highe than the oiginal value, thee is a mismatch occued between the input impedance and chaacteistics impedance of an antenna tends to maximum eflection to the input signal. This shows that the length l 2 plays a cucial ole in the pefomance of poposed antenna design. Fig. 8 shows the simulated input etun loss by changing the slot length l 3. By adjusting the length lowe and highe than the oiginal value, thee is no change noted in the esult. This slot length povides complete impedance matching to antenna. One thing noticed that the minimum eflection occued at most lowe and highe fequencies, but this can be handled by optimizing the slot length accoding to the need. Fig. 9 shows the simulated input etun loss esults by changing the dielectic thickness (h). In this case, the pemittivity of the mateial is kept constant as given in Section II and the thickness is changed fom lowe to highe value. It is noticed, when minimum value is taken which is 1.27 mm, antenna gives bette esponse as compaed to the othe paametic study. Also, it is noticed that gadually incease in thickness will affect the antenna pefomance. So, fom this obsevation it can be say that the use of thin substate is also useful fo the pesented design. IV. Conclusion A multiband factal slot shaped micostip patch antenna is designed fo micowave applications. Seven esonant fequencies ae achieved accoding to 10 db bandwidth citeia. The esonant fequencies occued in the ange of 1-20 GHz. Also, the VSWR of poposed antenna is 2. The maximum gain achieved fo lowe fequency bands is up to 9 dbi and minimum gain is -7 dbi and the aveage gain achieved fo the highe fequency bands is 5dBi. Paametic study is also obtained to demonstate the pefomance of poposed antenna. The poposed design is useful fo Bluetooth, WLAN, ada and satellite communication, etc. Fig. 2. Simulated input etun loss of poposed multiband micostip patch antenna. Fig. 3. Simulated VSWR of poposed multiband micostip patch antenna. 46 Page

5 Fig. 4. Simulated gain of poposed multiband antenna fo lowe esonant fequencies. Fig. 5. Simulated gain of poposed multiband antenna fo uppe esonant fequencies. Fig. 6. Simulated input etun loss by changing slot length l 1. Fig. 7. Simulated input etun loss by changing slot length l Page

6 Fig. 8. Simulated input etun loss by changing slot length l 3. Fig. 9. Simulated input etun loss by changing substate/dielectic thickness (h). Refeences [1] C. A. Balanis, Antenna Theoy and Design, 3 d Edition. [2] V.-A. Nguyel, R.-A. Bhatti and S.-O. Pak, A simple PIFA-based tunable intenal antenna fo pesonal communication handsets, IEEE Antennas Wieless Popag. Lett., vol. 7, pp , [3] N. Behbad and K. Saabandi, Dual-band econfiguable antenna with a vey wide tenability ange, IEEE Tans. Antennas Popag., vol. 54, no. 2, pp , [4] H. Okabe and K. Takei, Tunable antenna system fo 1.9 GHz PCS handsets, IEEE Antennas Popag. Int. Symp., vol. 1, pp , [5] D. Peoulis, K. Saabandi and L. B. P. Katehi, Design of econfiguable slot antennas, IEEE Tans. Antennas Popag., vol. 53, no. 7, pp , [6] F. Yang and Y. R. Samii, A econfiguable patch antenna using switchable slots fo cicula polaization divesity, IEEE Mico. Wieless Comp. Lett., vol. 12, no. 3, pp , [7] K.-M. Lee, Y.-J. Sung, J.-W. Baik and Y.-S. Kim, A tiangula micostip patch antenna fo multi-band applications, Asia Pacific Micowave Conf., pp. 1-4, [8] K. Chung, Y. Nam, T. Yun and J. Choi, Reconfiguable micostip patch antenna with switchable polaization, ETRI Jounal, vol. 28, no. 3, [9] P. Muthili, P. Cheian, S. Midula and D. Paul, Design of a compact multi-band micostip antenna, 2009 Annual India Conf., pp. 1-4, [10] G. Jegan, A. V. Juliet and G. A. Kuma, Multiband micostip patch antenna fo satellite communication, Recent Adv. Space Tech. Sevices and Climate Change, pp , [11] S. S. Patel and Y. P. Kosta, Multiband PBG suspended patch antenna, 3 d Int. Conf. Electonic and Compute Tech., vol. 2, pp. 5-9, [12] H.-C. Ryu, H.-R. ahn, S.-H. Lee and W. S. Pak, Tiple-stacked micostip patch antenna fo multiband system, Elect. Lett., vol. 38, no. 24, pp , Page