A Corporate Fed Coplanar Folded Slot Antenna Array and Its ...
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A Corporate Fed Coplanar Folded Slot Antenna Array and Its Application for Beam Steering Mina A. Iskander 1 , RongLin Li 1 , Dimitris E. Anagnostou 1, 2 1 ECE Department South Dakota School of Mines and Technology Rapid City, SD 57701 USA Email: [email protected] Michael T. Chryssomallis 2 2 ECE Department Democritus Univ. of Thrace Xanthi, 67100, Greece Email: [email protected] Benjamin D. Braaten 3 3 ECE Department North Dakota State University Fargo, ND, 58102 Email: [email protected] Abstract—We demonstrate a corporate fed coplanar folded slot antenna (CFSA) array and its application for beam steering. The design methodology, the return loss and the radiation pattern measurements of the CFSA array are presented. The beam steering of the array can be achieved by using a phased array that is incorporated with three phase shifters. I. INTRODUCTION The coplanar folded slot antenna (CFSA) has the advantage of easy realization. A reconfigurable coplanar folded slot antenna without bias network has been demonstrated in [1]. For a high gain or a phased beam steering application, a CFSA array is needed. A useful technique for a CSFA array is to use a feed, such as those described in [2], [3]. However, a series feed usually leads to a narrow bandwidth and a frequency- dependent radiation pattern, and that is not suitable for a phased array for beam steering. In this paper, we demonstrate a corporate fed CFSA array and its phased array application. II. CORPORATE FED CFSA ARRAY The geometry of a corporate fed coplanar folded slot antenna (CFSA) array is illustrated in Figure 1. The CFSA array consists of four CFSA elements. The design of the individual CFSA element has been described in [1] and [4]. The CFSA has several interesting characteristics. It has more gain and more bandwidth than the dipole antenna, and it is conformal and uni-planar. It can also be made flexible by using thin bendable substrates. The design of the CFSA array was carried out based on an RO4003C substrate with ε r = 3.38. A microstrip corporate network is used to feed the CSFA array. There is a transition between the microstrip line and the CPW feed for each CFSA element. For the transition, the ground planes for the micostrip lines and of the CPW lines are connected by an array of vias. The input impedance of each CFSA element is designed to be 100 Ohms. A 70-Ohm quarter-wave transformer is incorporated in the CPW feeding network to achieve good impedance matching between the 100-Ohm of each CFSA element and the 50-Ohm characteristic impedance of the corporate feed. A prototype of the corporate fed CFSA array is displayed in Fig. 2. The simulated and measured results for the return loss of the CFSA array are plotted in Fig. 3. Results show a resonant frequency around 5 GHz. The simulated and measured radiation patterns at 5.1 GHz are compared in Fig. 4. Good agreement is observed. The antenna gain of the CFSA array is more than 10 dBi at 5.1 GHz. Folded slot antenna Feed network x y z Figure 1. Geometry model of the 4x1 corporate fed CFSA array. Figure 2. Photo of the prototype of the corporate fed 4x1 CFSA array with the SMA connector. The vias of the microstrip to CPW transition can be observed. 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 30 25 20 15 10 5 0 Measured Simulated Return loss (dB) Frequency (GHz) Figure 3. Simulated and measured return loss of the 4x1 CFSA array. A resonance around 5.1 GHz with large bandwidth (approximately 4.8 GHz to 5.4 GHz) is observed. 978-1-4673-0462-7/12/$31.00 ©2012 IEEE
Transcript of A Corporate Fed Coplanar Folded Slot Antenna Array and Its ...
A Corporate Fed Coplanar Folded Slot
Antenna Array and Its Application for Beam Steering
Mina A. Iskander1, RongLin Li1, Dimitris E. Anagnostou1, 2
1 ECE Department South Dakota School of Mines and Technology
Rapid City, SD 57701 USA Email: [email protected]
Michael T. Chryssomallis2 2 ECE Department
Democritus Univ. of Thrace Xanthi, 67100, Greece
Email: [email protected]
Benjamin D. Braaten3 3 ECE Department
North Dakota State University Fargo, ND, 58102
Email: [email protected]
Abstract—We demonstrate a corporate fed coplanar folded slot antenna (CFSA) array and its application for beam steering. The design methodology, the return loss and the radiation pattern measurements of the CFSA array are presented. The beam steering of the array can be achieved by using a phased array that is incorporated with three phase shifters.
I. INTRODUCTION
The coplanar folded slot antenna (CFSA) has the advantage of easy realization. A reconfigurable coplanar folded slot antenna without bias network has been demonstrated in [1]. For a high gain or a phased beam steering application, a CFSA array is needed. A useful technique for a CSFA array is to use a feed, such as those described in [2], [3]. However, a series feed usually leads to a narrow bandwidth and a frequency-dependent radiation pattern, and that is not suitable for a phased array for beam steering. In this paper, we demonstrate a corporate fed CFSA array and its phased array application.
II. CORPORATE FED CFSA ARRAY
The geometry of a corporate fed coplanar folded slot antenna (CFSA) array is illustrated in Figure 1. The CFSA array consists of four CFSA elements. The design of the individual CFSA element has been described in [1] and [4]. The CFSA has several interesting characteristics. It has more gain and more bandwidth than the dipole antenna, and it is conformal and uni-planar. It can also be made flexible by using thin bendable substrates. The design of the CFSA array was carried out based on an RO4003C substrate with εr = 3.38. A microstrip corporate network is used to feed the CSFA array. There is a transition between the microstrip line and the CPW feed for each CFSA element. For the transition, the ground planes for the micostrip lines and of the CPW lines are connected by an array of vias. The input impedance of each CFSA element is designed to be 100 Ohms. A 70-Ohm quarter-wave transformer is incorporated in the CPW feeding network to achieve good impedance matching between the 100-Ohm of each CFSA element and the 50-Ohm characteristic impedance of the corporate feed.
A prototype of the corporate fed CFSA array is displayed in Fig. 2. The simulated and measured results for the return loss of the CFSA array are plotted in Fig. 3. Results show a
resonant frequency around 5 GHz. The simulated and measured radiation patterns at 5.1 GHz are compared in Fig. 4. Good agreement is observed. The antenna gain of the CFSA array is more than 10 dBi at 5.1 GHz.
Folded slot antenna
Feed networkx
y
z Figure 1. Geometry model of the 4x1 corporate fed CFSA array.
Figure 2. Photo of the prototype of the corporate fed 4x1 CFSA array with the SMA connector. The vias of the microstrip to CPW transition can be observed.
4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.030
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urn
loss
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)
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Figure 3. Simulated and measured return loss of the 4x1 CFSA array. A resonance around 5.1 GHz with large bandwidth (approximately 4.8 GHz to 5.4 GHz) is observed.
978-1-4673-0462-7/12/$31.00 ©2012 IEEE
H-plane x
z
270o300o
330o
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|E| (dB) -40 -30 -20 -10 0180o
150o
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Figure 4. Simulated and measured radiation patterns of the 4x1 CFSA array at 5.1 GHz illustrating the directive broadside radiation.
III. PHASED CORPORATE FED CFSA ARRAY
The geometry of the phased corporate fed CFSA array is depicted in Fig. 5. The distance between two adjacent elements is about half a wavelength. Three phase shifters are added to the CFSA array for beam tilting. The phase shifters are designed to achieve a 10 beam steering. Therefore the electrical length difference between two adjacent phase shifters is about 30. The return loss of the phased CFSA array is plotted in Fig. 6. Good impedance matching is achieved around the 5 GHz frequency range, with return loss > 20dB at the design frequency of 5 GHz. The simulated radiation pattern at 5 GHz is plotted in Fig. 7 and shows a 10 beam steering, as expected. Experimental results for the phased CFSA array will be presented at the conference.
Folded slot antenna
Feed networkPhase shifterx
y
z Figure 5. The geometry of a phased corporate fed CFSA array. The microstrip phase delay lines can be observed.
4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.830
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Figure 6. Return loss of the phased corporate fed CFSA array.
H-plane x
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Figure 7. Radiation pattern of the phased corporate fed CSFA array at 5 GHz.
ACKNOWLEDGEMENT
This work was supported in part by the DARPA/MTO Young Faculty Award under agreement number N66001-11-1-4145, the US Army Research Laboratory/Army Research Office under agreement number W911NF-09-1-0277, NASA under Cooperative Agreement NNX07AL04A and NASA ND EPSCoR under Cooperative Agreement 0017786.
REFERENCES
[1] D. E. Anagnostou and A. A. Gheethan, “A Coplanar Reconfigurable Folded Slot Antenna Without Bias Network for WLAN Applications”, IEEE Antennas and Wireless Propagation Letters, vol. 8., pp. 1057-1060, Sept. 2009.
[2] V. J. Marrero-Fontanez and R. A. Rodriguez-Solis, “Dual polarized aperture-coupled microstrip patch antenna for X-band series-fed array,” Antennas and Propagation Society International Symposium, pp. 2148-2151, 2007.
[3] D. E. Anagnostou, J. Papapolymerou, M. M. Tentzeris, and Christos G. Christodoulou, “A Log-Periodic Koch Dipole Arrays (LPKDA)”, IEEE Antennas and Wireless Propagation Letters, v.7, pp: 456-460, Dec. 2008.
[4] A. A. Gheethan and D. E. Anagnostou, “Broadband and Dual-band Coplanar Folded-Slot Antennas (CFSAs)”, IEEE Antennas and Propagation Magazine, Volume 53, Issue 1, pp. 80 – 89, Feb. 2011.
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