Review Paper for Broadband CPW-Fed T-Shape Slot Antenna

Transcription

1 Review Paper for Broadband CPW-Fed T-Shape Slot Antenna Shahpure Sana 1, Bharate Rajashri 2, Prof. Jadhav D.A. 3 1,2 BE, Dept. of E&TC, Brahmdevdada Mane Institute of Technology, Dist. Solapur (Maharashtra) 3 Assistant professor, E&TC Dept. Brahmdevdada Mane Institute of Technology, Dist. Solapur (Maharashtra) Abstract A novel broadband design of a coplanar waveguide (CPW) fed T-shape slot antenna is proposed and experimentally studied. The size of the proposed antenna is reduced by over 26% compared to the reported wide slot antenna. The obtained results show that the impedance bandwidth, determined by 10-dB return loss, of the proposed slot antenna can be as large as 5690MHz or about 121% centered at about GHz. The design considerations for achieving broadband operation of the proposed slot antenna are described, and experimental results are presented.this Paper presents T-shape slot antenna with a coplanar wave guide (CPW). In this paper we compare the parameters of T-shape slot antenna, Microstrip patch antenna, Folded Slot antenna, slot antenna for wideband application. Because the CPW-fed wide slot antennas have the advantages of wide bandwidth and easy integration with monolithic microwave integrated circuit, the designs of the CPW-fed wide slot antennas have recently received much attention. The antenna shape and its dimensions were first searched by using the Ansoft s High Frequency Structure Simulator (HFSS) and then the optimal dimensions were determined from experimental adjustment. Keywords T-Shaped slot antenna, CPW, Broadband, Microstrip antenna, Folded Slot antenna. I. INTRODUCTION The antenna is the interface between the transmission line and space. Antennas are passive devices; the power radiated cannot be greater than the power entering from the transmitter When speaking of gain in an antenna, gain refers to the idea that certain directions are radiated better than others Antennas are reciprocal - the same design works for receiving systems as for transmitting system.recently, wireless communications have been developed widely and rapidly, which leads to a great demand in designing broadband antennas for mobile terminals [1]. Among various forms of planar antennas, coplanar waveguide-fed printed slot antennas have the simplest structure of a single metallic layer. Because the CPW-fed wide slot antennas have the advantages of wide bandwidth and easy Integration with monolithic microwave integrated circuit, the designs of the CPW-fed wide slot antennas have recently received much attention. For a simple CPW-fed square slot antenna, the impedance bandwidth (10-dB return loss bandwidth) can reach about 30%. A few attempts have been made to increase the bandwidth of CPW-fed antennas. As for the CPW-fed slot antennas with strip-loaded [1] or with a widened tuning stub [1] can reach 60%. II. A BROADBAND CPW-FED T-SHAPE SLOT ANTENNA Among various forms of planar antennas, coplanar waveguide-fed printed slot antennas have the simplest structure of a single metallic layer. Fi 1. Geometry of the proposed CPW-fed T-shape slot antenna [1]. A. Experiment Results Table 1gives the antenna parameters and the measured center frequency and bandwidth for the constructed prototypes with various lengths of L1and L2. Measured results of the return loss against frequency are also presented in Figure 2. It is clearly seen that owing to the configuration of the T-shape slot antenna, a new resonant mode is excited. When proper L1and L2 are selected, this new resonant mode can be shifted close to the antenna s fundamental resonant mode, resulting in a wide impedance bandwidth. From the results obtained, the maximum impedance bandwidth is as large as 5690MHz or about 121% centered at about GHz. Fig 2. Measured return loss against frequency for the proposed antenna [1]. 334

2 Table I. Performance of the proposed antenna with a fixed length antenna L1(mm) L2(mm) f c (MHz) Bandwidth (MHz) % , , , , ,49 Performance of the proposed antenna with a fixed length of (L) of 22.5 mm, a b = 40mm 35 mm, εr = 4.4,h = 1.6 mm, ground-plane size= 60mm 60 mm [1].Radiation characteristics of the antenna at operating frequencies within the impedance bandwidth obtained have also been studied. Fig. 3 plots the measured radiation patterns in the y-z plane and x-y plane for frequencies within the impedance bandwidth of the proposed antenna with L1= 6 mm, L2 = 14mm (antenna4). The Results show that the proposed antenna has a peak antenna gain of about 4.8 dbi, with gain variations less than 3 dbi across the operating bandwidth from 1.8 GHz to 6 GHz. III. CIRCULAR MICROSTRIP PATCH ANTENNA The circular microstrip antenna resonates at 1.58 GHz and 2.43 GHz, which enables it s usage in the wireless communication domain such as in Wireless Local Area Network (WLAN).By varying the lengths of the rectangular slot, the proposed antenna can provide a tunable frequency ratio of 1.50 to 1.62 for the two operating frequency band [2]. The performance of a low-profile coplanar waveguide (CPW)-fed monopole antenna comprising of a straight strip, a parasitic circular-hat patch, and a slotted CPW ground for broadband operation is presented.a measured dual-frequency operation with a broad impedance bandwidth(10 db return loss) of 77% from GHz, the 3.5/5.5 GHz WiMAX, and the 5.2/5.8 GHz WLAN standards, has finally been explored. The moment method code, IE3D, was used for required numerical analysis to examine the performance of the proposed antenna configurations in terms of achieving the broad bandwidth. Fig 3. Measured radiation patterns for antenna 4, at 5.2 GHz [1]. The measured results show that the near omnidirectional radiation pattern can be obtained. It is because the symmetrical configuration of the T-shape slot antenna. Fig 5. Geometry of the proposed broadband CPW-fed monopole antenna with parasitic load [2]. A. Experiment Results: Fig 4. Measured antenna gain for antenna 4 [1]. Fig 6. Measured return loss against frequency for the proposed antenna [2]. 335

3 For the Circular Microstrip patch antenna the return loss obtained is 10 db. In microstrip patch antenna stable monopole-like radiation pattern and an average antenna gain of 4.0 dbi across the operating band have been obtained. IV. CPW-FED FOLDED-SLOT ANTENNA FOR 5.8 GHZ RFID TAGS Coplanar waveguide (CPW)-fed capacitive folded-slot antenna is proposed for the radio frequency identification (RFID) application at 5.8 GHz. The antenna is fabricated on a 30_30 mm substrate. The measured bandwidth and antenna gain are 7.5% and 4.2 dbi, respectively. Radiation patterns are almost omnidirectional in the H-plane. These properties and the compact and uniplanar structure make the antennas suitable for use as RFID tags. The design process, simulations were carried out on a package software IE3D from Zeland [3]. Fig 7. Geometry of CPW-fed capacitive folded-slot antenna [3]. A.Experiment Results: Fig 8. Simulated and measured input return losses of prototype antenna [3]. simulated measured Simulated and measured input return losses are shown and compared in Figure 8. The measured input impedance bandwidth (return loss >10 db) of the prototype antenna is ~7.5% ( GHz), while the simulated bandwidth is ~6.2% ( GHz). The simulated and measured results are in good agreement. (a) E-plane pattern (b) H-plane pattern Fig 9. Radiation patterns of prototype antenna measured at 5.85 GHz [3]. co-polarisation cross-polarisation The E- and H-plane radiation patterns measured at 5.85 GHz are shown in Figure 9 (a) and (b), respectively. The radiation patterns are broadside and bidirectional in the E-plane and almost omnidirectional in the H-plane, and the measured peak antenna gain is 4.2 dbi. It should be mentioned that, if the substrate width W is mad narrower, then the radiation pattern will become more uniform in the H-plane; however, all other parameters have to be readjusted to obtain a new input match. V. CPW-FED SLOT ANTENNA FORWIDEBAND APPLICATIONS A new coplanar waveguide (CPW)-fed wideband printed slot antenna is presented, and the impedance characteristics of this antenna with different sizes of tapers are discussed. The effect of tapering angle with the resonant frequency is also observed. The fundamental parameters of the antenna such as bandwidth, return loss, gain, radiation pattern, and polarization are obtained. All meets the acceptable antenna standards. The measured input impedance bandwidth (return loss < 10 db) of the prototype antenna is 52% ( GHz). The radiation patterns are bidirectional in both planes. This antenna can be part of various wireless communication systems. The dimensions of the antenna by simulation with the aid of IE3D electromagnetic software were studied and then adjusted by experiment. 336

4 Fig 10. The geometry of the proposed coplanar waveguide (CPW)-fed slot antenna [4]. A. Experiment Results: Fig 11. Return loss versus frequency [4]. Simulated and measured input return losses are shown and compared in Figure 11. The measured input impedance bandwidth (return loss < 10 db) of the prototype antenna is 3.31 GHz ( GHz), while the simulated bandwidth is 2.85 GHz ( GHz). Though the simulated and measured results are in good agreement, it can be made still better if fabrication precision is increased. (a) E-plane pattern (dbi) (b) H-plane pattern (dbi) Fig 12. Radiation patterns of antenna measured at 6.06 GHz [4]. Due to limited testing facilities, only simulated radiation patterns are presented. The E- and H-plane radiation patterns simulated at 6.06 GHz are shown in Figures 12 (a) and 12(b), respectively. The radiation patterns are bidirectional in the E-plane and H-plane. It should be noted that cross polarization levels are well controlled in E-plane and H-plane. Moreover, antenna is linearly polarized. Fig13. Gain versus frequency [4] 337

5 The gain-versus-frequency characteristics are given in Figure 13. The simulated peak antenna gain is 4.39 dbi at 8 GHz. VI. CONCLUSION The Broadband CPW-Fed T-Shape slot antenna has the advantage over all the antenna is that, it has the less return loss, i.e. 10-dB. Omnidirectional radiation pattern, It is because the symmetrical configuration of the T-shape slot antenna, and it has a peak antenna gain of about 4.8 dbi, with gain variations less than 3 dbi across the operating bandwidth from 1.8 GHz to 6 GHz.In addition to the advantages of low cost, simple structure, and wide operating band, the T-shape slot antenna has nearly omnidirectional radiation for all operating bands including PCS, 3G, Bluetooth, DMB and WANL and gain variation of the range in each of the bands can be less than 3 dbi. REFERENCES [1] J.-J. Jiao, G. Zhao, F.-S. Zhang, H.-W. Yuan, and Y.-C. Jiao, Broadband CPW-fed T-shape slot antenna, Progress In Electromagnetics Research, PIER 76, [2] Sonali Jain, Prof. Rajesh Nema, Review paper for circular Microstrip patch antenna, International Journal of Computer Technology and Electronics (IJCTEE) Volume 1, Issue 3. [3] S.-Y. Chen and P. Hsu, CPW-fed folded-slot antenna for 5.8 GHz RFID tags, Electronics Letters 25th November 2004 Vol. 40 No. 24. [4] T. Shanmuganantham, K. Balamanikandan, and S. Raghavan, CPW-Fed Slot Antenna forwideband Applications, Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume 2008, Article ID , 4 pages doi: /