Beam switching dual polarized antenna array with

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present a good impedance match (this is due to a change of the impedance seen ... [6] H. Boutayeb, K. Mahdjoubi, and A.C. Tarot, “Analysis of radius- periodic ...
> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT)
REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < state resistor Ron = 1.5ohm in series with inductor Lind = 0.45nH and off-state inductor Lind = 0.45nH in series with parallel RC circuit of Roff = 30kΩ and Coff = 0.14pF. We consider H = 10mm, Dw = 3.2mm, Dclear = 8mm, and P = 20.4mm. These parametrs were obtained by optimizing the transmission coefficients of the waveguide in the two states and by optimizing the matching of the radial waveguide presented in the next Section.

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of the inductive line of the wire in the middle was decreased by 2mm in order to maximize and flater the transmission coefficient in the passband.

Port 2

Substrate Metallic wire with diameter D

Port 1

H

(a)

Floquet boundaries P (a)

Dclear Inductive microstrip line with length L

Metallic wire pad

Dw RF Choke (b) Fig.2. Frequency responses of the structure for L = 0.5mm (a) diodes are ON (b) diodes are OFF

PIN diode (b)

Substrate with thickness ts

Floquet boundaries Metallic wire

PEC surfaces

(a)

(c) Fig.1. Model for designing proposed periodic reconfigurable structure

As shown in Fig.2, for small value of the length L (L=0.5mm), a passband can be obtained in on-state in the the frequency band of interest (5GHz-6GHz). If L is increased by about a quarter guided wavelength, the passband is observed in offstate, as shown in Fig. 3. In these both modes of operations the two states allow to reconfigure between stopband and passband in the band 5GHz-6GHz. The second mode of operation (Fig. 3) where the passband is observed with the diodes in off-state is prefered because the insertion loss is lower for this case (between 0.3 and 0.52dB compared to between 1.25dB and 1.62dB). Also, it should be noted that in the second mode of operation (Fig. 3), the length

(b) Fig.3. Frequency responses of the structure for L = 9.2mm (a) diodes are ON (b) diodes are OFF

> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < III. RECONFIGURABLE RADIAL WAVEGUIDE POWER DIVIDER Based on previous analysis, Fig. 4 presents the reconfigurable radial waveguide power divider designed using ring PCBs, a center probe excitation and 12 output ports with printed probes. The cylindrical periodic structures of wires follow the principle of using constant transversal period as proposed in [6]-[8]. For the output ports, E-plane probes are used and there is a quarter-wave separation to the outer perimeter which serves as a short circuit termination. The periodic structure has 36 PIN diodes connected into pairs. The configuration of the diodes state shown in Fig. 4(b) permits to divide the power mostly between ports 2 and 3. The dc feed circuit with the radial stubs, the PIN diodes and the inductive lines are shown more clearly in Fig. 5. As shown in this figure, the inductive lines have different lengths and widths at different radial position in order to optimize the frequency response of the structure.

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driving the diodes. We noticed that increasing further this voltage doesn’t decrease significantly the insertion loss. Due to the symmetry and the shape of the configuration in Fig. 4(b), we can limit our analysis to the reflection coefficient of port 1 and the transmission coefficients from port 1 to port 2 (coupled port), port 4 (adjacent uncoupled port) and port 5 (uncoupled back port). Other transmission coefficients are deduced from the symmetry and the fact that the transmitted power decreases from port 4 (close to region with diode in offstate) to port 5 (far from region with diode in off-state). PIN diode

Resistor R=200Ω

dc line

Position of dc connector

Fig.5. Zoom on the dc feed circuit

H=10mm D=172mm (a) Region with diodes in OFF state Port 1

Port 2

Port 3 Port 4 Fig.6. Measuring S parameters of reconfigurable radial waveguide

Port 5 (b) Fig.4. Architecture of the proposed reconfigurable radial waveguide power divider (a) perspective view (b) top view

Fig.7. Simulated and measured S11 and S21

Figure 6 shows the setup for the measurement of the S parameters of the prototype using the configuration of the diodes states shown in Fig. 4(b). A voltage of 1.5V is used for

For the considered configuration, the optimized reflection coefficient S11 of the structure and the transmission confidents S21, S41 and S51 are plotted in Figs.7-9.

> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < There are fair agreements between simulated and experimental results. In the band 5.15-5.85GHz, ports 4 receive less than 25dB and port 5 receives less than -40dB of the power. Port 2 (and port 3) receives most of the power. The insertion loss can be obtained by adding S21 and S31. In the band 5.18-5.825GHz, the simulated insertion loss is between 0.4dB and 0.7dB and the measured insertion loss is between 1.2dB and 2.3dB. The higher insertion loss in measurements could be due to higher value of serial resistance of PIN diodes than the value given by the manufacturer, defect during fabrication (such as hand soldering) and tolerance in the parameters of the substrate. Further experimental investigation is required to evaluate more precisely the origin of the additional measured loss. Lower insertion loss could be achieved by using tunable elements with lower serial resistances. For our prototype, we choose purposely a PIN diode that was easy to solder by hand.

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located diagonally across the element are excited with single 50Ω port, which results in 180 excitation phase between the diagonal pin pairs. This results in separate +45 or -45 polarization with a single patch. Two patch antennas are implemented vertically in order to increase the directivity in the elevation plane. For the vertical radiator pairs, a single substrate is used. The patch dimension is a square of 15.6mm, and the distance between the patch and the ground is 8.8mm. The diameter of the pins is 0.5mm.

(a) (b) Fig.10. Dual slant polarized antenna (a) model in HFSS (b) photo

The simulated and measured reflection coefficient and radiation patterns of the patch antenna pairs are shown in Figs.11-13 at center frequency. Measured reflection coefficients are lower than -15dB and port-to-port coupling is lower than -22dB. Measured Xpol patterns are lower than 13dB and even lower than -20dB close to the direction angle of the main beam. These characteristics are important in order to use this radiator in an array configuration

Fig.8. Simulated and measured S41

Fig.11. S Parameters of the two port dual polarized radiator

Fig.9. Simulated and measured S51

IV. DUAL POLARIZED ARRAY ELEMENT Figure 10 presents the two port dual slant (+45/-45) polarized antenna that we consider as an element for the circular array presented in next Section. The objective is to design an antenna with two orthogonal polarizations in order to be able to send two data streams simultaneously. The proposed radiator is composed of two patch antennas. Each patch is excited through four pins (two pins for each polarization) using capacitive coupling principle. Two pins

Fig.12. Copol and Xpol patterns at 5.5 GHz in H plane for one port (similar patterns are obtained for the second port)

> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT)
REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < azimuth plane, the measured beam-width is about 30. Xpol patterns are lower than -14dB within the main beam. The measured realized gain is about 12dB whereas the simulated directivity is about 14dB. The loss is mostly attributed to the radial waveguide and the PIN diodes.

Fig.19. Measured reflection coefficient of the antenna omnidirectional and symmetric directive configurations

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present a good impedance match (this is due to a change of the impedance seen by the center probe). The other directive configurations (as in Fig. 4(b)) that are circularly periodic with an angular period of 60, present similar impedance matching. For these directive beam configurations, measured radiation patterns at 5.5 GHz are presented in Fig. 20.

for Fig.22. Measured Copol and Xpol patterns at 5.5 GHz in H plane (Azimuth) for 30 beam direction configuration

Fig.20. Measured Copol and Xpol patterns at 5.5 GHz in H plane for configurations with beam direction at every 60 step.

Fig.21. Measured reflection coefficient of the antenna for different 30 beam direction configuration and for multiple beams

Figure 19 presents the measured reflection coefficient of the antenna for different configurations. It can be noted that the omnidirectional configuration (all diodes are off) doesn’t

Fig.23. Measured Copol and Xpol patterns at 5.5 GHz in H plane (Azimuth) for two beams configuration

Fig.24. Measured Copol and Xpol patterns at 5.5 GHz in H plane (Azimuth) for three beams configuration

The beam switching can be obtained with smaller angular step or with multiple beams. As examples, Fig. 21 presents the

> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < measured reflection coefficient for beam direction at 30, for two beams and for three beams. For these configurations, good impedance matching (S11 < -10dB) can be obtained in parts of the 5GHz band. For these three configurations, the measured Copol and Xpol patterns are shown in Figs. 22-24. Other configurations are also possible: since we use 18 dc ports to control the 36 diodes, there are theoretically 2 18 different configurations that can be programmed for each port. However, we can limit this number of configurations to those which give sufficiently different patterns and who have good impedance matching at the operating frequency band. VI. CONCLUSION A new technique for designing dual polarized beam switching antennas was proposed. These antennas are based on reconfigurable radial waveguides excited by central probes and feeding multiple radiating elements. A circularly periodic structure of metallic wires loaded with tunable elements (PIN diodes) is used to reconfigure the power distribution of the radial waveguide. An analysis method was proposed for the design of this structure by using a rectangular periodic structure. The radial waveguide power divider was designed, fabricated and tested, validating the proposed concept. Then, a full agile antenna was designed, fabricated and measured. The obtained results show that this antenna is suitable for WIFI applications in the 5GHz band, with the utilization of a simple 1.5V battery for driving the PIN diodes.

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Band Gap Structure for Low Power and Low Cost Smart Antenna Systems”, in Proc. IEEE Antenna and Propagation Symposium 2014, Memphis, June 2014. Halim Boutayeb (M’03 -SM’11) received in 2000 the Diplôme d’Ingénieur (B.Sc.) degree in Electrical Engineering from the École Supérieur d’Ingénieur de Rennes, France, and the French D.E.A. (M.Sc.) degree in Electrical Engineering from the University of Rennes, Rennes, France. He received the Ph. D. degree in Electrical Engineering in the same university in December 2003. From March 2004 to December 2006, he was with INRS-EMT, Montréal, QC, Canada. From January 2007 to December 2011, he was a Researcher with the École Polytechnique de Montréal, Montréal, QC, Canada. He was also a Coordinator and a member of the Centre de Recherche en Électronique Radiofréquence (CREER), which is a strategic cluster that provides a unique platform for putting together 40 Canadian researchers in the field of applied electromagnetics and RF technologies. Since Jan. 2012, he has been a Research and Development Staff Member with the Huawei Technologies Company Ltd., Ottawa, ON, Canada. He has authored or coauthored more than 90 journal and conference papers. Since 2003, he has been a Reviewer for a number of scientific journals and conferences. He has 16 patent grants and applications. His main fields of interest are antennas, microwaves circuits, computational electromagnetism, artificial materials, radars, local positioning systems, biomedical engineering, and phased arrays. Dr. Boutayeb is a Senior Member of the Professional Engineers of Quebec. He has served several times as a Technical Program Committee member (VTC, NEMO, ANTEM, IMS) and he served as a Steering Committee member of the IEEE Microwave Theory and Techniques Society (IEEE MTT-S) International Microwave Symposium (IMS) 2012. He was a recipient of the Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship Grant (2004–2006), the Best Paper Award of the European Conference on Antennas and Propagation (2004, previous name: Jounees Internationales de Nice sur les Antennes), and two Gold Huawei Medal Awards (2013 and 2015).

REFERENCES M. Chryssomallis, “Smart antennas,” IEEE Antennas Propag. Mag., vol. 42, pp. 129–136, 2000. [2] A. Alexiou and M. Haardt, “Smart antenna technologies for future wireless systems: Trends and challenges,” IEEE Commun. Mag., vol. 42, no. 9, pp. 90–97, Sep. 2004. [3] G. Cerri, R. De Leo, V. M. Primiani, C. Monteverde, and P. Russo, “Design and prototyping of a switching beam disc antenna for wideband communications,” IEEE Trans. Antennas Propag., vol. 54, no. 12, pp. 3721–3726, Dec. 2006. [4] M.-I. Lai, T.-Y. Wu, J.-C. Hsieh, C.-H. Wang, and S.-K. Jeng, “Compact switched-beam antenna employing a four-element slot antenna array for digital home applications,” IEEE Trans. Antennas Propag., vol. 56, no. 9, pp. 2929–2936, Sep. 2008. [5] R. Vaughan, “Switched parasitic elements for antenna diversity”, IEEE Trans. Antennas Propagation, vol. 47, no. 2, pp. 399-405, Feb. 1999. [6] H. Boutayeb, K. Mahdjoubi, and A.C. Tarot, “Analysis of radiusperiodic cylindrical structures”, in Proc. IEEE AP-S Int. Symp. Dig., vol. 2, pp. 813- 816, June 2003. [7] H. Boutayeb, “Étude des Structures Périodiques Planaires et Conformes Associées aux Antennes. Application aux Communications Mobiles,” (in French) Ph.D. dissertation, Univ. Rennes, Rennes, France, 2003. [8] H. Boutayeb, T. Brillat, J. Daniel, F. Gadot, P. Garel, A. De Lustrac, K.Mahdjoubi, P. Ratajczak, and A.-C. Tarot, “A reconfigurable electromagnetic bandgap structure for a beam steering base station antenna,” in Proc. 27th ESA Antenna Technol. Workshop Innovative Periodic Anten., Santiago de Compostela, Spain, Mar. 2004. [9] M. Niroo Jazi et al., “Electronically sweeping-beam antenna using a new cylindrical frequency selective surface,” IEEE Trans. Antennas Propag., vol. 61, no. 2, pp. 666–676, Feb. 2013 [10] B. Liang, B. Sanz-Izquierdo, E. A. Parker, And J. C. Batchelor “Cylindrical slot FSS configuration for beam-switching applications,” IEEE Trans. Antennas Propag., vol. 63, no. 1, pp. 166–173, Jan. 2015. [11] H. Boutayeb, P. Watson, and T. Kemp, “New Reconfigurable Power Divider Based on Radial Waveguide and Cylindrical Electromagnetic [1]

Paul R. Watson received the B.E.Sc degree (electrical) from the University of Western Ontario, London, Ontario, Canada in 1989, followed by graduate studies at the University of Ottawa, Ottawa, Ontario, Canada. He has held positions as a GaAs IC Power Amplifier Designer, and for the last 10 years as an Antenna Designer. His current research and design interests include antenna and array innovation in massive mimo and full duplex applications, as well as frequency selective surfaces applied to antennas.

Weishan Lu received the B.S. degree in information engineering from Guangdong University of Technology in 2009 and received the M.S. degree in Communication System in South China University of Technology in 2012. He has worked on the WiFi standardization at the communication technology lab in Huawei, China. Currently, he is working on the protocol design and the antenna design in smart living and IOT area.

Tao Wu received the BE and MS degrees from the Electronic Engineering and Information Science Department, University Of Science and Technology of China, in July 1998 and July 2001. Since 2005, he has been a senior engineer in Huawei Technologies, Co. Ltd. and his work has been focused on the wireless standard development and long term research.