Performance Evaluation of a noval
Reconfigurable Microstrip Patch Antenna using RF MEMS Switch
Monu Kumar1, Vaishali Singh2, Dharmendra Verma3, Amit Kumar4
[email protected] , [email protected], [email protected], [email protected]
1,2,M.Tech Student, 3,4 Assistant Professor, Department of Electronics & Communication Engineering SITE, Swami Vivekanand Subharti University, Meerut, India
20
International Journal of Advanced Engineering Science and Technological Research (IJAESTR) ISSN: 2321-1202, www.aestjournal.org @2016 All rights reserved
Abstract
A Performance Evaluation of a noval reconfigurable Microstrip patch antenna using RF MEMS switch is presented in this paper. The antenna is designed to achieve the reconfigurability within the band i.e. C-band.
The antenna exhibits the property of change in frequency which results in change in return loss characteristics depending upon the configuration request. The frequency reconfiguration capability of antenna is achieved with the help of metal strip line which acts as a switch to reconfigure the antenna. Small rectangular slots are cut out of patch to insert switches to obtain reconfigurability.
The antenna is simulated on Ansoft HFSS software. The simulated results give high gain & wide band of 6.27 GHz in the range of 6.725 GHz with switches first ON.
And we can also see the result on different frequency with different switches condition.
Keywords: Reconfigurable Antenna, Microstrip Patch Antenna RF MEMS Switch.
1-Introduction
Microstrip or patch antennas are becoming increasingly useful because they can be printed directly onto a circuit board. Microstrip antennas are becoming very widespread within the mobile phone market. Patch antennas are low cost, have a low profile and are easily
fabricated. Consider the Microstrip antenna shown in Figure 1, fed by a Microstrip transmission line. The patch antenna, Microstrip transmission line and ground plane are made of high conductivity metal (typically copper). The patch is of length L, width W, and sitting on top of a substrate (some dielectric circuit board) of thickness h with permittivity εr. The thickness of the ground plane or of the Microstrip is not critically important. Typically the height h is much smaller than the wavelength of operation, but should not be much smaller than 0.025 of a wavelength (1/40th of a wavelength) or the antenna efficiency will be degraded.
The patch antenna with Right Hand Circular Polarization (RHCP) and Left Hand Circular Polarization (LHCP) with a single feeding port designed by Mohammad Ali, describes about two orthogonal slots are incorporated into the patch and two P I N diodes are utilized to switch the slots ON and OFF. The unique feature of this concept is RHCP &LHCP are time separated, (depending on the switch time of the diodes) so that there is no coupling between these two polarizations. The switching speed of the PIN diodes is slower than the MEMS-based switches.
The patch antenna with switchable slot (PASS).This concept is implemented to design a novel reconfigurable antenna with both frequency and polarization diversities.
21
Using only one switch and a single patch, the antenna operates at 6.20 GHz and at 6.27GHz.2-Reconfigurable Antenna
Reconfigurability, when used in the context of antennas, is the capacity to change an individual radiator‟s fundamental operating characteristics through electrical, mechanical, or other means. Thus, under this definition, the traditional phasing of signals between elements in an array to achieve beam forming and beam steering does not make the antenna “reconfigurable” because the antenna‟s basic operating characteristics remain unchanged in this case. Ideally, reconfigurable antennas should be able to alter their operating frequencies, impedance bandwidths, polarizations, and radiation patterns independently to accommodate changing operating requirements. However, the development of these antennas poses significant challenges to both antenna and system designers. These challenges lie not only in obtaining the desired levels of antenna functionality but also in integrating this functionality into complete systems to arrive at efficient and cost-effective solutions. As in many cases of technology development, most of the system cost will come not from the antenna but the surrounding technologies that enable reconfigurability.
In this paper, the Reconfigurable Microstrip Patch Antenna using Micro Electro Mechanical Systems (MEMS) technology for micrometer wave application was designed. The reconfigurable antenna is the antenna which adaptively changes it characteristics. The Reconfigurability is done by changing the status (ON &
OFF) of the MEMS cantilever switch. MEMS technology is a hot technology, to integrate both microelectronic circuits and mechanical structures on the same chip, enabling monolithic integration while reducing the micro system size and cost considerably.
The critical physical dimensions of MEMS devices can
vary from well below one micron to several millimeters.
These switches have near-zero power consumption, very high isolation, very low insertion loss and very high switching speed.
3-Design Specifications
The three essential parameters for the design of the Rectangular Microstrip Patch Antenna:
3.1-Calculation of Width (W): For an efficient radiator, a practical width that leads to good radiation efficiencies is given as
With the substituting the values of c= 3x10^8 m/s, fr and εr by using the above formula „W‟ can be calculated.
3.2-Calculation of Effective dielectric constant (εreff) The effective dielectric constant due to the air dielectric boundary is given by
With the substituting the values εr ,h and W effective dielectric constant εreff can be calculated using the above formula.
3.3-Calculation of effective length (Leff):
By choosing the substrate, the width and length of the patch can be estimated. An initial approximation for the length can be made for a half wave Microstrip antenna radiated by the formula:
4-Designed Antenna Structure 4.1 Antenna without Switches
22
The MSPA was designed to operate in C-Band that resonates at 6.38GHz. For switching cantilever type switch is used. The switch is removed from simulation when the switch is in OFF state.Fig 1: MSPA without switches
4.2 Antenna with First Switch ON
The MSPA was designed to operate in C-Band that resonates at 6.725GHz. The first switch is in ON mode it is added in the simulation. The second switch is in OFF mode so it is removed from simulation.
Fig 2: MSPA with first switch ON
4.3 Antenna with second switch ON
The MSPA was designed to operate in C-Band that resonates at 6.68GHz. The first switch is in OFF mode it is removed from the simulation. The second switch is in ON mode so it is added to the simulation.
Fig 3: MSPA with second switch ON
4.4 Antenna with both switch ON
The MSPA was designed to operate in C-Band that resonates at 7GHz. Both the switch is in ON mode and it is added in the simulation.
Fig 4: MSPA with both switches ON
5-Simulated Results 5.1 MSPA without switches
Fig: 5-3D radiation pattern (without switch)
Fig: 6- Graph for S11 (without switch)
23
Fig: 7- Graph for VSWR (without switch)Fig: 8- Radiation Pattern (gain without switch) 5.2 MSPA with first switch ON
Fig: 9- 3D radiation pattern (with switch-1)
Fig: 10- Graph for S11 (with switch-1)
Fig: 11- Graph for VSWR (with switch-1)
Fig: 12- Radiation Pattern (with switch-1)
5.3 MSPA with second switch ON
Fig: 13- 3D radiation pattern (with switch-2)
Fig: 14- Graph for S11 (with switch-2)
24
Fig: 15- Graph for VSWR (with switch-2)Fig: 16- Radiation Pattern (with switch-2)
5.4 MSPA with both switch ON
Fig: 17- 3D radiation pattern (with both switch)
Fig: 18- Graph for S11 (with both switch)
Fig: 19- Graph for VSWR (with both switch)
Fig: 20- Radiation Pattern (with both switches)
6-Conclusion
The design of a Reconfigurable Microstrip Patch Antenna with resonant frequency of 7GHz was designed using ANSOFT HFSS and the different operating frequencies of 6.38, 6.68, 6.75GHz we are obtained using RF MEMS switch. The Reconfigurable Microstrip patch antenna can expand the system capability. By adjusting its resonant frequency, radiation pattern and polarization the reconfigurable antenna can accommodate various requirements of wireless communication. Microstrip antennas are widely used in satellite and mobile communications systems because of their light weight and planar shape.
7-Reference
1. G.H. Huff and J.T. Bernhard. (2008).
"Reconfigurable Antennas". In C.A.
25
Balanis. Modern Antenna Handbook. John Wiley & Sons.2. Peroulis, D., K. Sarabandi, and P. B. K. Katehi,
"Design of reconfigurable slot antennas," IEEE Transactions on Antennas and Propagation, Vol. 53, 645-654, 2005.
3. A Reconfigurable Patch Antenna Using Switchable Slots for Circular Polarization Diversity by Rahmat Samii & Yang, IEEE Microwave And Wireless Components Letters, Vol. 12, No. 3, March 2002.
4. A Wideband E-Shaped Microstrip Patch Antenna For 5–6 Ghz Wireless Communications by B.-K. Ang and B.-K.
Chung ,Progress In Electromagnetics Research, PIER 75, 397–407, 2007.
5. A Reconfigurable Stacked Microstrip Patch Antenna for Satellite and Terrestrial Links by Mohammod Ali, IEEE transactions on vehicular technology, vol. 56, no. 2, march 2007.
6. Erdil, E; Topalli, K; Unlu, M; Civi, O; Akin, T (2007). "Frequency tunable microstrip patch antenna using RF MEMS technology". IEEE Trans. Antennas Propagation 55 (4).
7. X.S., Yang; Wang, B.Z.; Wu, W.; Xiao, S.
(2007). "Yagi Patch Antenna With Dual-Band
and Pattern Reconfigurable
Characteristics". IEEE Antennas Wireless Propag. Lett. 6.
8. A Novel Patch Antenna with Switchable Slot (Pass): Dual-Frequency Operation with Reversed Circular Polarization by Nanbo Jin,Fan Yang and Yahya Rahmat-Samii , IEEE transactions on antennas and propagation, vol.
54, no. 3, march 2006.
9. Huff, G. H., F. S. Zhang, and J. T. Bernhard,
"A novel radiation pattern and frequency reconfigurable single turn square spiral
microstrip antenna," IEEE Microwave and Wireless Components Letters, Vol. 13, 57-59, 1998.
