2011 Loughborough Antennas & Propagation Conference
14-15 November 2011, Loughborough, UK
A Switchable Ultra-wideband (UWB) to TriBand Antenna Design M.Jusoh1, M.F.Jamlos2, M.F.Malek3, M.R.Kamarudin4 and M.S.Mustafa5 1-2
Nature and Defense Centre (NDeC), School of Computer and Communication Engineering 3 School of System Electric Engineering 4 Wireless Communication Centre (WCC), Faculty of Electrical Engineering 5 School of Computer and Communication Engineering 1-3,5 Universiti Malaysia Perlis (UniMAP), 3Universiti Teknologi Malaysia (UTM) 1
[email protected] [email protected] 3
[email protected] 4
[email protected] 5
[email protected]
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Abstract—A switchable ultra-wideband (UWB) to tri-band antenna with the presence of the three RF switches is presented. The proposed antenna capable to perform UWB at 2.7GHz to 11.9GHz and tri-band antenna at band 1 (2.43GHz to 2.65GHz), band 2 (3.18GHz to 6.58GHz) and band 3 (7.41GHz to 10.81GHz) under the minimum impedance matching of -10dB. The novel design antenna with a partial ground has a compact size of 38 mm x 38 mm. Furthermore, the simulated antenna gain demonstrates 5.5dBi for the high speed wireless digital communication system. The simulated of ideal switch fully reveal the performance of the projected antenna.
I. INTRODUCTION Reconfigurable antenna, switchable antenna and multi mode antenna are carrying the interpretation of the same type of antenna. It means an antenna with a multi-frequency band by different radiation pattern, polarization and directivity at each band controlled by electronically switches. Recently, the intention of switchable antenna has expanded a lot among the researchers. Switchable antenna is suitable for mobile communication and military application where it can support multi function on a single multi mode antenna. Hence, the antenna size and cost can be reduced compared to the separate utility of conventional antenna. Theoretically studied, the dynamically reconfigurable antenna can be realized by using RF switches such as PIN diodes, MEMs and GaAs FETs. The presence and absence of the RF switches respectively known as ‘ON’ and ‘OFF’ state actually be able to do the frequency tuning [1]-[7]. This paper described and analyzed the performance of the compact switchable antenna incorporate with the three PIN diode switches. The activation of specified PIN diode switches configuration would then decide the operating frequency. The antenna capable to switch from frequency functioning of UWB (2.7GHz to 11.9GHz) to tri-band
978-1-4577-1016-2/11/$26.00 ©2011 IEEE
frequency mode (2.43GHz to 2.65GHz, 3.18GHz to 6.58GHz and 7.41GHz to 10.81GHz). Meanwhile, this design development has fulfilled the new modern mobile and wireless communication device which is compaction, handy and switchable frequency [7].The proposed antenna has potential to be future candidate for cognitive radio and radar communication system [8]-[10]. The simulated and measured results of the proposed antenna are presented in details. All the design and simulation has been carried out by CST Microwave Studio software. The fabrication and measurement processes involve is done in the cluster research of Universiti Malaysia Perlis (UniMAP). II. ANTENNA DESIGN
(a)
(b)
Fig.1. Geometry of the simulated switchable antenna. (a) Front view. (b) Back view. As depicted in Fig. 1(a), the configuration of the developed novel antenna design consists of seven outer small circles and one inner circle in the middle of antenna. Fig. 1(b) shows the partial ground at the back of the substrate. The proposed
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2011 Loughborough Antennas & Propagation Conference
antenna is printed on the Taconic substrate known as TLY-5 with thickness of t=1.5748mm, r=2.2 and tangent loss, tan=0.0009. The size of the substrate is 38mm square, Wsub x Lsub. The seven small circles has similar diameter of Rout=6mm. While, the inner circle is develop with Rin=12mm. A microstrip line feed is used with a normal impedance matching of 50 to excite the frequency resonance. A good impedance matching is important to reduce the difference between the adjacent circuits, referred to the radiating element and feed line. This will reflect to the more power is transmitted to the antenna element rather than reflected back to the source (SMA connector). The antenna is fed with length Lf=8.28 mm. The width of fed is significant to ensure the 50 impedance is achievable. This Wf can be calculated by using impedance calculation properties provided by CST Microwave Studio software. The optimum value of Wf=5 mm. The integration of RF switches with the antenna element was monitored to switch the UWB to Tri-Band modes. In simulation, the switches are representing as 2 mm x 1mm copper strips labeled by S1, S2 and S3 with black color in Fig.1. The switching devices can be controlled by ensuring the ON and OFF mode. When the switch is OFF, the strip line absence, gap exist which indicate no current flow through the gap. The switch is ON with the presence of the strip line [11]. An ultra-wideband operating frequency is feasible when all the switches in ON mode. More current flows through the PIN diodes. The tri-band is achieved when all the S1, S2 and S3 is in OFF mode. Means no current can flow through the switches. Finally, the real RF switches will be implementing and replace the copper strip lines. The RF switches are developed from the surface mount component (SMC) consists of one PIN diode, two DC (direct current) block capacitor, two RF choke inductor and a DC supply. It can function when there is a DC current flow through PIN diode (ON). Hence, the inductors play a major role to ON the PIN diode instead chokes the alternating current (AC) from flow to the DC supply and ground. Whereas capacitors will block the DC current and allow RF and AC signals to flow simultaneously. III. RESULTS AND DISCUSSION Measurement and simulation show that the proposed switchable planar antenna has a great agreement which be able to operate for UWB and tri-band. A UWB can be achieved by switch on all the switches. Means more current will flow through the strip line when inner circle is attached to the small circle of 2, 4 and 6 as in Fig.1. A tri-band is realized when all the strip line is detached or all switches is in OFF mode. Fig.2 emphasis clearly the variations of the return loss versus frequency for the attention band is less than 10dB (|S11|-10dB) either for simulated or measured. The simulated
14-15 November 2011, Loughborough, UK
UWB impedance matching bandwidth is 4.4:1, 2.7GHz to 11.9GHz while measured show 3.2:1, 3.4GHz to 10.8GHz. The simulated tri-band frequency mode indicates 2.43GHz to 2.65GHz, 3.18GHz to 6.58GHz and 7.41GHz to 10.81GHz. Whereas the measured tri-band demonstrates 2.55GHz to 2.75GHz, 3.3GHz to 6GHz and 7.7GHz to 9.1GHz.
Fig.2 Simulated and measured return loss of the proposed antenna. There are some principles which contributed to the inconsistency between the measured and simulated results such as a slight difference on the fabricated and computer generated antenna dimension due to the manual fabrication process. Moreover, the simulation has no consideration for the loss of the SMA connector while measurement does. In addition, regards to the numerous number of lump element components has deteriorates the measurement result. Fabrication also has generated the existence of the soldering copper which increases the unwanted antenna structure as well as affected the antenna performance. Fig.3 plots the simulated co-polar and cross-polar of the presented antenna for UWB and tri-band at particular frequencies, 3.7GHz and 9.3GHz correspondingly. It can be seen that the radiation pattern of the UWB and tri-band is approximately similar at excited frequency 3.7GHz and differ at excited frequency 9.3GHz. An extensive study has been made related to current distribution over UWB and tri-band of the presented antenna. As in Fig.4, a comparison has been made for both bands at particular operating frequency respectively, 3.7GHz and 9.3GHz. It can be observed that the excitation for UWB has divergence contrast to tri-band for the comparable frequency. Significantly, there are no current distributions into the inner circle for UWB compared to tri-band over the studied frequencies. This shows for tri-band the current has been obstructing from flow through the switches.
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2011 Loughborough Antennas & Propagation Conference
14-15 November 2011, Loughborough, UK
(a) UWB
Tri-band (a) 3.7GHz
(b) UWB
Tri-band (b) 9.3GHz
Fig.4 Simulated current distribution for the proposed antenna excited at 3.7GHz and 9.3GHz.
IV. CONCLUSION
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(d) Fig.3 Radiation pattern of the proposed antenna. (a) UWB excited at 3.7GHz. (b) UWB excited at 9.3GHz. (c) Tri-band excited at 3.7GHz. (d) Tri-band excited at 9.3GHz.
A switchable UWB to tri-band antenna has been accessible. It is verified that the presence/absence of copper strip lines can be represent as ON/OFF RF switches for the initial simulation design. Then, the real lump element will be placed at the ideal location with a certain PIN diodes configuration. The return loss simulation result carried out from CST Microwave Studio is comparable to measure outcome at the minimum attainable impedance matching for the targeted operating band (|S11|-10dB). Moreover, the simulated radiation pattern and current distribution for both band at 3.7GHz and 9.3GHz has been discussed evidently in chapter IV. In due to a novelty design, small in size and ability of switchable for two modes (ultra-wideband and tri-band), the obtainable antenna has great potential to be applicable for cognitive radio and radar communication system as well.
REFERENCES [1]
M.R. Hamid, P. Gardner, P.S. Hall, F. Ghanem, “Switchable WidebandNarrowband Tapered Slot Antenna,” 2009 Loughborough Antennas & Propagation Conference. 16-17 November 2009, Loughborough, UK.
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2011 Loughborough Antennas & Propagation Conference
14-15 November 2011, Loughborough, UK
Qiang Chen, Makoto Kurahashi and Kunio Sawaya, “Dual-mode Patch Antenna Switched by PIN Diode,” 2003 IEEE Topical Conference on Wireless C6mmunication Technology. [3] S. V. Shynu, G. Augustin, C. K. Aanandan, P. Mohanan, and K. Vasudevan, “Design of Compact Reconfigurable Dual Frequencies Microstrip Antennas Using Varactor Diodes,” Progress in Electromagnetic Research, PIER 60, 197–205, 2006. [4] F. Ghanem, J.R. Kelly, and P.S. Hall, “Switched UWB to Narrowband Planar Monopole Antenna,” European Conference on Antennas and Propagation 2010, 12-16 April 2010, Barcelona. [5] M. T.Ali, T. A. Rahman, M.R. Kamarudin and M. N. Md Tan. “Reconfigurable Linear Array Antenna with Beam Shaping at 5.8GHz,” Microwave Conference, 2008. APMC 2008. Asia-Pacific. [6] Kiriazi, J., Ghali, H., Ragaie, H., Haddara, “Reconfigurable dual-band dipole antenna on silicon using series MEMS switches,” Antennas and Propagation Society International Symposium, Vol. 1, pp. 403-406, (2003). [7] M.F. Jamlos, O. A. Aziz, T. A. Rahman, M. R. Kamarudin, P. Saad, M. T. Ali and M. N. Md Tan, “A Beam Steering Radial Line Slot Array (RLSA) Antenna With Reconfigurable Operating Frequency,” J. of Electromagnetic Waves and Appl. Vol. 24, 1079-1088, 2010. [8] J. R. Kelly, E. Ebrahimi, P. S. Hall, P. Gardner, and F. Ghanem, “Combined Wideband and Narrowband Antennas for Radio Applications,” Cognitive Radio and Software Defined Radios: Technologies and Techniques, 2008 IET. [9] Hall P S, Gardner P, Kelly J, Ebrahimi E, Hamid M R, Ghanem, Herraiz-Martínez F J, and Segovia-Vargas D., “Reconfigurable Antenna Challenges for Future Radio Systems,” Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference. [10] Prof. Igor J. Immoreev, James D. Taylor, P.E., “Future of Radars,” Ultra Wideband Systems and Technologies, 2002. Digest of Papers. 2002 IEEE Conference. [11] M. T. Ali, M. N. M. Tan, T. A. Rahman, M. R. Kamarudin, M. F. Jamlos and R. Sauleau, “A Novel Reconfigurable Planar Antenna Array (RPAA) with Beam Steering Control,” Progress In Electromagnetics Research B, Vol. 20, 125-146, 2010. [2]
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