Low Cost 60 GHz Smart Antenna Receiver Sub-System Based on Substrate Integrated Waveguide Technology

1156 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 60, NO. 4, APRIL 2012

Low-Cost 60-GHz Smart Antenna ReceiverSubsystem Based on SubstrateIntegrated Waveguide Technology

Fan Fan He, Ke Wu, Fellow, IEEE, Wei Hong, Senior Member, IEEE, Liang Han, and Xiao-Ping Chen

Abstract—In this paper, a low-cost integrated 60-GHz switched-beam smart antenna subsystem is studied and demonstrated ex-perimentally for the first time based on almost all 60-GHz sub-strate integrated waveguide (SIW) components including a slot an-tenna, 4 4 Butler matrix network, bandpass filter, sub-harmoni-cally pumped mixer, and local oscillator (LO) source. In this study,an antenna array, a Butler matrix, and a bandpass filter are inte-grated and fabricated into one single substrate. Instead of using a60-GHz LO source, a 30-GHz LO source is developed to drive alow-cost 60-GHz sub-harmonically pumped mixer. This 30-GHzLO circuit consists of 10-GHz SIW voltage-controlled oscillatorand frequency tripler. Following the frequency down-conversionof four 60-GHz signals coming from the 4 4 Butler matrix and acomparison of the four IF signals executed in the digital processorbased on the maximum received power criterion, control signalswill be feed-backed to drive the single-pole four-throw switch arrayand then the beam is tuned in order to point toward the main beamof the transmit antenna. In this way, the arriving 60-GHz RF signalcan be tracked effectively. All designed components are verifiedexperimentally. The proposed smart receiver subsystem that inte-grates all those front-end components is concluded with satisfac-tory measured results.

Index Terms—Beamforming, Butler matrix, smart antenna,60 GHz, sub-harmonically pumped mixer, substrate integratedwaveguide (SIW), switched beam.

I. INTRODUCTION

T HE WORLDWIDE introduction of the unlicensed fre-quency band around a 60-GHz frequency range has

opened up new avenues and created new opportunities for highdata-rate wireless applications [1], [2]. The massive amountof available spectrum covering the 57–64-GHz range in theU.S. is larger than the total of all other unlicensed spectrums,which leads to a low-cost implementation of high data-rate de-manding wireless applications [3], [4]. Being much higher thanthe power limits of other unlicensed spectrums, the equivalent

Manuscript receivedMay 20, 2011; revised December 22, 2011; accepted De-cember 28, 2011. Date of publication February 10, 2012; date of current versionApril 04, 2012.This work was supported in part by the Canada Research ChairProgram, by the Canadian Natural Sciences and Engineering Research Council(NSERC) under a Strategic Grant, and under Quebecer FQRNT funds.F. F. He, K. Wu, L. Han, and X.-P. Chen are with the Poly-Grames Research

Center, Department of Electrical Engineering, École Polytechnique de Mon-tréal, Montréal, QC, Canada H3T 1J4.W. Hong is with the State Key Laboratory of Millimeter Waves, Southeast

University, Nanjing 210096, China.Color versions of one or more of the figures in this paper are available online

at http://ieeexplore.ieee.org.Digital Object Identifier 10.1109/TMTT.2012.2184127

isotropic radiated power (EIRP) limit on the transmit signalimposed by the Federal Communications Commission (FCC)is 40 dBm, which augments the attractiveness of this spectrum[2]. Possible applications include, but are not limited to, wire-less high-quality video transfer including uncompressed HDTVsignals, point-to-point wireless data links replacing opticallinks, and video/music transfer from/to portable devices, all ofwhich are required to provide link speeds in the gigabit/secondrange [5], [6]. The main limitations associated with the 60-GHzfrequency range are high propagation loss including oxygen ab-sorption, immaturity of the circuit technology, high directivityof the antennas, and limited wall penetration. These limitations,however, can also be desirable in some cases because theycan reduce the interference and increase the frequency reuse,and hence, the network security. The possibility of reducedinterference and higher frequency reuse makes the 60-GHzband an attractive solution for short-range indoor broadbandcommunications.While helping in alleviating the problem of high propagation

losses, the use of highly directive antennas with high gain incommunication systems necessitates a perfect beam alignmentof the transmitter and receiver because a small mismatch cancause signal degradation of several decibels [7], [8] or even outof range. An adaptive smart antenna system can solve the align-ment problem by adaptively steering the beams of the trans-mitter or the receiver to maximize the signal power at all times.Many authors have proposed solutions in attempt to overcomethe power requirement and alignment challenges of the 60-GHzsystems using antenna arrays [7]–[9]. Even though smart an-tenna systems can solve the alignment and propagation lossproblems, additional channels to the RF front-end will increasethe already high hardware costs several folds while exponen-tially increasing the computational requirements of the system.Low gain and large beamwidth array elements are extensivelyused in [10]–[12] to increase the angular coverage, but a similarrequirement for a large number of RF channels make the situ-ation worse. Therefore, much simpler antenna beam-switchingsystems, employing several highly directional elements, is de-sirable to steer the beam to predefined directions with negli-gible computational complexity and costs. The switched-beamantenna using the Butler matrix network [9]–[14] is a cost-ef-fective approach to implementing an adaptive antenna in themicrowave and millimeter-wave range.Recently, substrate integrated waveguide (SIW) structures

have attracted much attention from both academia and industrycommunities. A SIW can be synthesized in the substrate by

0018-9480/$31.00 © 2012 IEEE

HE et al.: LOW-COST 60-GHz SMART ANTENNA RECEIVER SUBSYSTEM BASED ON SIW TECHNOLOGY 1157

metallic via-arrays utilizing the standard printed circuit board(PCB) or low-temperature co-fired ceramic (LTCC) process.Microwave and millimeter-wave components based on SIWtechniques, which can be easily integrated with other planar cir-cuits, have the advantages of high- factor, low insertion loss,and high power capability. Therefore, a number of applicationsbased on the SIW technique have been reported in [15]–[19].Specially, a number of 60-GHz components and systems havebeen designed and demonstrated with good results using theSIW techniques [20]–[29]. However, not all circuits in thosereported 60-GHz RF front-end systems were developed usingthe SIW techniques.This paper describes the design of a low-cost 60-GHz

switched-beam smart antenna receiver subsystem based on theSIW technique, which presents a high-density integration offront-end components into one single substrate. Described inSection II are the system design and analysis of the proposedsmart antenna subsystem. In Section III, the antenna and allcircuits in the 60-GHz RF front-end of interest are designedincluding the filter, Butler matrix, mixer, and local oscillator(LO). Section IV presents the design of IF circuits block anddigital control circuits block as parts of the subsystem. InSection V, the entire smart antenna subsystem with integratedbuilding blocks is demonstrated and measured with goodresults.

II. SYSTEM DESIGN CONSIDERATIONS ON 60-GHzSWITCHED-BEAM SMART ANTENNA RECEIVER SUBSYSTEM

Fig. 1 illustrates the configuration of the proposed switched-beam smart antenna system. The 60-GHz base-station receiverconsists of three sectors, each of which covers a 120° area. Eachsector is composed of one 4 4 Butler matrix antenna sub-system. In this subsystem, the SIW slot antenna, SIW Butlermatrix, and SIW bandpass filter are all integrated together intoone substrate. This design is able to overcome the interconnec-tion and integration problem between such millimeter-wave cir-cuits and radiating elements.Here, a SIW linear slot array antenna is chosen because it has

over 120 3-dB beamwidth in the -plane and a gain higherthan a microstrip patch antenna, which is very important in mil-limeter-wave applications. The work frequency of this antennais specified from 58 to 60.5 GHz. In order to avoid the problemof grating lobes, an array spacing of a half-wavelength in freespace is normally chosen. Four SIW linear slot array slot an-tennas are connected with a 4 4 SIWButler matrix that is usedto generate four fixed beams covering an area of 120 . A SIWbandpass filter working from 58.5 to 63 GHz is then connectedwith each input port of the Butler matrix. To amplify the re-ceived signal, a ceramic substrate with 10-mil thickness is nec-essary for wire-bonding the 60-GHz low-noise amplifier (LNA)chip die.To down-convert the 60-GHz signals to the IF of 1.5 GHz, a

sub-harmonically pumped mixer using antiparallel diode pairsis designed, which considers low mutual coupling effects. It iswell known that a high-power 60-GHz signal source is very ex-pensive and difficult to design. The sub-harmonically pumpedmixer is used with the driving of a low pumping frequency, and

Fig. 1. Configuration of the proposed switched-beam smart antenna subsystem.

the cost of the system is reduced accordingly. In addition, thismixer provides AM noise suppression and no requirement ofdc-bias circuits. Instead of using a 60-GHz LO source in ourcase, a 30-GHz LO source is developed to drive the sub-har-monically pumped mixer. This LO circuit consists of a SIW10-GHz VCO proposed in Section III, drive amplifiers, and a10-to-30-GHz SIW tripler. After the frequency down-conver-sion of four 60-GHz signals, we can obtain four IF signals. RFchains are defined in the subsystem as channels 1–4 from left toright, as shown in Fig. 1. Each IF signal is filtered, amplified,coupled to the detector, and finally sent to an Advanced RISCMachines (ARM) processor to judge the maximum receivedpower among the four IF signals by an algorithm of compar-ison. Following the comparison of the four IF signals, a controlsignal will drive the single-pole four-throw (SP4T) switch cir-cuits, and the beam is then tuned and pointed accordingly to themain beam of the transmit antenna. That is to say, the arriving60-GHz RF signal can be effectively tracked, which is the prin-cipal function of the proposed smart antenna system with thebeam-switched technique. Details of those circuits in the pro-posed system are described below.In this study, the receiver system is a heterodyne structure.

The second IF-to-baseband down-conversion is neglected be-cause we only consider how to automatically switch the beamin the study. Thus, this is also called an IF adaptive beam-switched system. The IF adaptive structure can sharply decreasethe cost and complexity of the baseband circuits. Meanwhile,the IF adaptive structure presents a much better cost–perfor-mance tradeoff than its RF adaptive counterpart because it iscurrently difficult to design a low-cost 60-GHz switch and a de-tector with a good performance compared with IF components.


Fig. 2. Simulated normalized radiation patterns in - and -plane at 59.5 GHzof one sub-array.

III. DESIGN OF THE ANTENNA AND RF FRONT-ENDOF THE PROPOSED SMART ANTENNA

A. Design of the SIW Feed Slot Array Antenna

As mentioned in Section II, the SIW linear slot array antennais chosen for the smart antenna system in this study. This an-tenna can easily be integratedwith other circuits withminimizedinterference, which leads to a cost-effective subsystem. SomeSIW slot antenna arrays and beam-forming networks have beendeveloped [19]–[28]. In this study, the 60-GHz SIW slot antennaarray is proposed with the maximum gain of 22 dBi and the cor-responding efficiency of about 68% [24]. Therefore, the theoryand procedure of the SIW slot antenna are not described here.In the proposed system, only one sub-array from [24] is used

and is fabricated on the substrate Rogers/Duroid 6002 with20-mil thickness and dielectric constant . The simu-lated bandwidth defined for 10-dB return loss is 2.3 GHz from58.5 to 60.7 GHz. The 3-dB beamwidth of -plane radiationpattern is about 140 , which is found very suitable for the 4 4Butler matrix beam forming architecture, as shown in Fig. 2.The antenna also provides a high gain of about 13.5 dBi.

B. 60-GHz RF Front-End Design

In this section, the proposed 60-GHz SIW hybrid integratedsubsystem is developed using the SIW components, includingpassive and active circuits, except for the LNA.In this design, the 60-GHz RF front-end is composed of a

SIW Butler matrix, filters, sub-harmonically pumped mixers,60-GHz LNAs, and 30-GHz LO source, as described by ourexperimental prototype in Fig. 3. First of all, the SIW Butlermatrix is studied and developed. Next, a 60-GHz SIW band-pass filter is designed for its use between the Butler matrix andthe LNA. Subsequently, a section of conductor-backed coplanarwaveguide (CBCPW) is used to connect and match the LNAcircuit and the filter. Further, the 60-GHz LNA is used to am-plify the received signal after the filter. Afterwards, the 60-GHz

Fig. 3. Photograph of the RF Front-end with the antenna array.

sub-harmonically pumped mixer is developed as a frequencydown-converter. Finally, the 30-GHz LO is designed that incor-porates a SIW VCO and a tripler according to the requirementsof the subsystem.1) SIW Butler Matrix: In this system, we use the conven-

tional 4 4 Butler matrix composed of 90 hybrids, crossovers,and 0 phase shifters, as shown in Fig. 4. In our designed Butlermatrix, the 90 hybrids and crossovers are realized with the SIWshort-slot couplers [29]. To achieve relative flat phase differ-ences between the ports of the Butler matrix, the self-compen-sating SIW phase shifter [30] is adopted in our design. The struc-ture of a phase shifter consists of delay lines (SIW bends) and asection of wider SIW.To validate the design, the Butler matrix is simulated using

the HFSS package and measured with the slot antenna. How-ever, the developed eight-port Butler matrix cannot be directlymeasured because of the lack of -band connectors in our labo-ratories. In fact, it is not an accurate and guaranteed way to usingmultiple -band connectors to test multiport circuits, as the fre-quency response of those connectors are generally not uniformand it would be difficult to identify the source of the problem ifany.Table I shows the simulated performance of the Butler matrix

in 58–61 GHz where ports 1–4 are input ports and ports 5–8 areoutput ports. Simulated transmission coefficients suggest that


Fig. 4. Configuration of the Butler matrix network with antenna.

TABLE IPERFORMANCE OF THE BUTLER MATRIX

Fig. 5. Physical description of the SIW cavity filter.

the entire Butler matrix has the insertion loss of about 1.4 dB at59.5 GHz.The Butler matrix integrated with the slot antenna array is

simulated and then measured in system in Section V. The returnlosses and isolations are greater than 19 dB in the working band.From the simulated -plane radiation patterns, it can be ob-served that the main beam directions are at 42 correspondingto input ports 2 and 3, and 15 to input ports 4 and 1, respec-tively. The simulated gain is 18 dBi when port 1 or 4 is excited.2) 60-GHz SIW BandPass Filter: In a typical receiver archi-

tecture, it is necessary to apply a bandpass filter before the LNA.The 60-GHz SIW filter is naturally chosen for our subsystem de-sign because it has an excellent performance and also an easy in-tegration with the Butler matrix. As with the filter design in [31],a four-order Chebyshev SIW cavity filter is designed, as shownin Fig. 5. Details of the parameters of the filter are mm,

mm, mm, ,and . In our measurement, a -band test fixtureand thru-reflect-line (TRL) calibration method are used. Fig. 6shows simulated and measured frequency responses of the filter.The insertion loss and return loss in the passband are around1.2 dB and greater than 15 dB from 58 to 63 GHz, respectively.3) 60-GHz LNA: In the RF front-end, a three-stage GaAs

monolithic microwave integrated circuit (MMIC) LNA HittiteHMC-ALH382, which has a high dynamic range and operating

Fig. 6. Simulated and measured frequency responses and group delay of theSIW bandpass filter.

Fig. 7. Measured frequency responses of the 60-GHz LNA model.

frequency range between 57–65 GHz, is used. This die chipLNA features 20 dB of small-signal gain, 4 dB of noise figure(NF), and an output power of 12 dBm at 1-dB compressionfrom a 2.5-V supply voltage. It is necessary to use a miniaturehybrid microwave integrated circuit (MHMIC) process to fabri-cate an LNA model with the HMC-ALH382 chip on a ceramicsubstrate with 10-mil thickness and dielectric constant .A CBCPW is used as the transmission line to connect the LNAchip and other components. Fig. 7 displays measured frequencyresponses of the LNA model. The measured gain of the LNA isabout 19 dB at 59.5 GHz.4) 60-GHz Sub-Harmonically Pumped Mixer: The proto-

type of the sub-harmonically pumped mixer is the same as theup-converter proposed in [32], except that the SIW filter is re-placed by a section of SIW in the 60-GHz mixer. The sectionof SIW is designed with the cutoff frequency at 50 GHz so highLO/RF and IF/RF isolations can be obtained. In this design, themixer is designed with an LO frequency of 29 GHz and an IFfrequency of 1.5 GHz. The circuit is designed and fabricatedon a Rogers/Duroid 6010 substrate with a dielectric constantof 10.2 and thickness of 0.254 mm. The Schottky antiparallel


Fig. 8. Measured conversion losses versus RF frequency.

Fig. 9. Basic block diagram of the -band LO source.

diode pair used is MGS802 from Aeroflex/Metalics Inc., Lon-donderry, NH.The measured conversion loss will remain around 16 dB

when the LO input power level is larger than 11 dBm, wherethe RF signal is fixed at 59.5 GHz with the input power levelof 20 dBm and LO frequency is 29 GHz. Therefore, theminimized LO input power level of 11.5 dBm is chosen topump the diode pair. Fig. 8 shows measured conversion lossesversus the IF frequency when the IF signal is swept from 58.4to 62 GHz with a constant input power level of 20 dBmand the LO signal is fixed at the frequency of 29 GHz with11.5-dBm power level. The measured 1-dB compression poweris 3 dBm.5) -Band LO Source Model: To drive the 60-GHz sub-

harmonically pumped mixer, a -band LO source model witha SIWVCO and a SIW frequency tripler is designed. Fig. 9 plotsthe basic block diagram of the proposed -band LO source.The RF power is developed by the SIW VCO presented in ourstudies [33]. This VCO can produce the RF signal with an outputpower of 6.5–9.8 dBm from 9.36 to 9.81 GHz. As the -bandbuffer amplifier, RFMD’s broadband InGaP/GaAs MMIC am-plifier NBB-310 is used to drive the SIW frequency tripler. Atleast an 15-dBm power level can be produced at the output ofthe amplifier. Through the SIW frequency tripler, the signal isconverted from 9.36–9.81 to 28.08–29.43 GHz. To meet thepower requirement of the LO of the sub-harmonically pumpedmixer, Hittite’s -band power amplifiers (PAs) HMC566LP4and HMC499LC4 are cascaded to obtain the power level of20–22 dBm.The designed tripler is a balanced passive multiplier uti-

lizing a planar Schottky antiparallel diode pair MGS802 fromAeroflex/Metalics Inc. A passive multiplier has the advantagesof being wideband and stable due to no dc supply. Using the

Fig. 10. Diagram of the SIW frequency tripler.

Fig. 11. Conversion loss versus input frequency for the designed frequencytripler.

antiparallel diode pair to build a tripler, the even harmonics aresuppressed inherently. That is, all even harmonics are shortedby the antiparallel diode pair. Fig. 10 shows the diagram of theSIW frequency tripler. At the input of the tripler, aopen-circuited stub on the right side of a diode pair is usedto provide a shorted terminal for frequency, where isthe fundamental frequency. A section of SIW with the cutofffrequency of 25 GHz is fabricated on the left side of the diodepair to suppress the fundamental and second harmonics andthen provide a good isolation at the output. The circuit isfabricated on a Rogers/Duroid 6010 substrate with a dielectricconstant of 10.2 and a thickness of 0.254 mm. The -bandfrequency tippler exhibits a measured conversion loss of14.8–16 dB for the input power of 11 dBm over the frequencyband of 27–36 GHz, as shown in Fig. 11. At the output fre-quency of 29 GHz, the conversion loss is about 15 dB. Fig. 12displays the measured output power versus the input power ofthe frequency tripler at the output frequency of 29 GHz.Using the circuits described here, the source is constructed as

shown in Fig. 13. Fig. 14 shows the output frequency and powerof the frequency tripler versus the varactor tuning voltage in thedesigned SIW VCO. As has been pointed out above, the mixerneeds 11.5-dBm LO power to pump the diode pair. Thus, thesubsystem needs the LO power of at least 17.5 dBm becausethere are four mixers in system. It can be seen that the designed-band source can meet the power requirement for the LO.

IV. IF CIRCUITS BLOCK WITH CONTROL BLOCK

The above section has described the four received 59.5-GHzRF signals at the four ports of the Butler matrix, which are am-


Fig. 12. Output power versus input power at 29 GHz.

Fig. 13. Photograph of the -band source model.

Fig. 14. Output frequency and power of the frequency tripler versus varactortuning voltage in VCO.

plified and frequency down-converted to the four 1.5-GHz IFsignals from IF1 to IF4, where IF1–IF 4 mean the four IF signalsfrom channels 1 to 4, respectively. This following part describeshow to compare the four IF signals and judge which channel re-ceives the maximum power, and then switch the beam to themain direction.The block diagram of the IF circuit, which consists of IF

low-pass filters, amplifiers, couplers, power detector, and dc

Fig. 15. Block diagram of IF circuit with control block.

filter, is shown in Fig. 15. The AVX low-pass filter has an in-sertion loss of 0.5- and 3-dB bandwidth of 2.6 GHz. After theAVX low-pass filter, an Infineon silicon–germanium broadbandMMIC amplifier BGA614 is used to amplify the IF signal. Theamplifier has a typical gain of 16 dB and an NF of 2 dB. Inorder to generate the four IF signals of comparison, four 10-dBcouplers are used, which were purchased from Johanson Tech-nology Inc., Camarillo, CA. The four coupling signals are thenintroduced to power detector AD8313 from Analog Devices,Norwood, MA, and the four main IF signals to SP4T switchAS204 from Skyworks Inc., Woburn, MA, respectively. De-tector AD8313 has a wide bandwidth of 0.1–2.5 GHz and a highdynamic range of 70 3.0 dB. The minimum detectable inputsignal power is about 75 dBm with output dc voltage of about0.5 V. The AS204-80 is a high-isolation SP4T field-effect tran-sistor (FET) integrated circuit (IC) nonreflective switch with adriver. The insertion loss is 0.5 dB and the isolation is 43 dB at1.5 GHz. At each IF input port, the minimum IF input power of65 dBm can be detected with an output dc voltage of 0.53 V.

That is, only a 1.5-GHz IF signal from a mixer with over 65dBm can be detected to judge which output of the Butler matrixhas the maximum received signal.Passing through the dc filter, the four detected dc signals

are then converted to digital signals by ADCs and sent into a[digital signal processing (DSP)] model. In this design, AtmelAT91SAM7SE512 is used as the DSP unit. AT91SAM7SE512is an ARM processor that provides integrated ADCs. This ADChas 10-bit resolution mode, and the conversion results are re-ported in a common register for all channels, as well as in achannel-dedicated register. The interval time between two sam-plings is 1 ms, which is enough for indoor communications be-cause most people walk at an average speed of 1.2–1.4 m/s.

V. EXPERIMENTS AND RESULTS

Before we test the entire receiver subsystem with a digitalblock, one channel of the receiver is measured from RF filterto IF coupler. Fig. 16 shows receiver’s NF and gain in the


Fig. 16. Measured receiver’s NF and gain versus RF frequency.

Fig. 17. Measured receiver’s output power and gain versus RF input power.

working band. Fig. 17 shows measured receiver’s output powerand gain versus RF input power. The input 1-dB compressionpoint power is 18 dBm.The entire subsystem with the ICs and components is mea-

sured using a 60-GHz experimental setup built as shown inFigs. 18 and 19. In the setup, a 60-GHz horn antenna (QuinstarQWH-VPRR00) with 24-dBi gain at 59.5 GHz and an Anritsu37397C vector network analyzer (VNA) are used as the trans-mitting antenna and the transmit signal source, respectively.There is a -band cable connected between the horn antennaand VNA, which has an insertion loss of 12 dB. The receiveris fixed at a stand with distance away from the transmit an-tenna. The distance can be changed by adjusting the transmitantenna’s position. In fact, the receiver in the center of the circlewith a radius of and the transmit antenna is on the circumfer-ence of the same circle. The transmit antenna can be manuallyrotated around the receiver from 90 to 90 to measure thebeams of the subsystem. To observe how the beams are switchedwhile the transmit antenna is rotated around the receiver, the

Fig. 18. Experimental setup diagram of the 60-GHz switched-beam smart an-tenna subsystem.

Fig. 19. Photograph of experimental setup of the 60-GHz switched-beam smartantenna subsystem.

output IF signal of the SP4T switch is fed to signal analyzerR&S FS2040. Meanwhile, -band LO circuits and IF circuitsare connected with the receiver fixed in the stand.Before the switchable function of the subsystem is tested and

demonstrated, the total channel gain of the RF front-end in-cluding an antenna is calculated by the received IF signals atthe output of the mixer. Channel gain can be expressed

(1)

where is the received IF signal power, is path loss in freespace, is the transmit signal power, is the gain of thetransmit antenna, is the gain of the received slot antenna,

is the gain of the LNA, is the loss of the Butler matrix,is the insertion loss of the filter, is the conversion loss

of the sub-harmonically pumped mixer, and is the insertionloss of the interconnection line coplanar waveguide (CPW).In the measurement, IF powers from the mixers of channels

1 and 2 are measured while is set as 7 dBm at 59.5 GHz anddistance is 30 cm, as well as the beam of the transmit antenna


Fig. 20. Calculated and measured gains of channels 1 and 2.

Fig. 21. Measured normalized received IF signal power versus scan angle at59.5 GHz.

aligned to beams 1 and 3 of the subsystem, respectively. is61 dB, which can be calculated by

dB (2)

Fig. 20 shows the calculated and measured gains of channels1 and 2 according to the measured IF signal. In channel 1 andchannel 2, the measured gains are about 13.5 and 11 dB, respec-tively. However, the measured gains are less than the calculatedcounterparts by about 3 dB, which may be caused by the ad-ditional insertion losses of interconnects and the Butler matrix.The channel gain decreases sharply at low frequency becausethere is the stopband of a 60-GHz bandpass filter. However, thechannel gain goes down slowly at high frequency because fre-quency is out of the working frequency range of the antenna.

TABLE IIPERFORMANCE COMPARISON

From the above section, it is known that the IF circuits can re-ceive the minimum IF signals of 65 dBm. Therefore, the min-imum received RF signal power of channels 1 and 2 are 78.5and 76 dBm.After the performance measurements of each channel, RF

front-end, IF circuits, and ARM evaluation board are allconnected to test the proposed switchable function of thesubsystem. The test method is to observe the IF signals fromthe IF circuits in the signal analyzer while the transmit hornantenna is rotated around the receiver. The measured IF relativepower versus the rotating angle is plotted in Fig. 21. It hasbeen found that the measured results not only agree very wellwith the simulated -plane pattern, but also indicate that thebeam can be successfully and adaptively switched to track thetransmitted beam.Finally, this study is compared with some other previously

published 60-GHz phased-array receiver studies, as shown inTable II.

VI. CONCLUSION

In this paper, a low-cost switched-beam smart antennareceiver susb-system has been studied, developed, and demon-strated on the basis of all 60-GHz components designed andfabricated with SIW technology including a slot antenna,4 4 Butler matrix network, bandpass filter, sub-harmonicallypumped down-conversion mixer, and LO source. In this system,the IF control circuit block and adaptive algorithm in the ARMare developed, respectively. Through a comparison algorithmin the ARM processor, the four beams are switched adaptivelywith a different main beam of the transmit signal. Thus, therealized subsystem is very suitable for low-cost 60-GHz indoorcommunication.

ACKNOWLEDGMENT

The authors would like to thank the Rogers Corporation,Rogers, CT, for providing free samples of dielectric substrates.The authors are also grateful to S. Dubé, Poly-Grames ResearchCenter, Montréal, QC, Canada, and A. Traian, Poly-GramesResearch Center, for the fabrication of our experimental pro-totypes.


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Fan Fan He was born in Nanjing, China. Hereceived M.S. degree in mec-electrical engineeringfrom Xidian University, Xi’an, China, in 2005, andis currently working toward the Ph.D. degree inelectrical engineering at both Southeast University,Nanjing, China, and the École Polytechnique deMontréal, Montréal, QC, Canada.He is currently an exchange student with the École

Polytechnique de Montréal. His current research in-terests include advanced microwave and millimeter-wave components and systems.


Ke Wu (M’87–SM’92–F’01) is a Professor ofelectrical engineering and Tier-I Canada ResearchChair in RF and millimeter-wave engineering withthe École Polytechnique de Montréal. Montréal, QC,Canada. He holds the first Cheung Kong endowedchair professorship (visiting) with Southeast Univer-sity, the first Sir Yue-Kong Pao chair professorship(visiting) with Ningbo University, and an honoraryprofessorship with the Nanjing University of Sci-ence and Technology, Nanjing University of PostTelecommunication, and City University of Hong

Kong. He has been the Director of the Poly-Grames Research Center and thefounding Director of the Center for Radiofrequency Electronics Research ofQuebec (Regroupement stratégique of FRQNT). He has also held guest andvisiting professorship with many universities worldwide. He has authored orcoauthored over 800 referred papers and a number of books/book chapters.He has served on the editorial/review boards of many technical journals,transactions, and letters, as well as scientific encyclopedia as an editor andguest editor. He holds numerous patents. His current research interests involvesubstrate integrated circuits (SICs), antenna arrays, advanced computer-aideddesign (CAD) and modeling techniques, wireless power transmission, anddevelopment of low-cost RF and millimeter-wave transceivers and sensorsfor wireless systems and biomedical applications. He is also interested in themodeling and design of microwave photonic circuits and systems.Dr. Wu is a member of the Electromagnetics Academy, Sigma Xi, and URSI.

He is a Fellow of the Canadian Academy of Engineering (CAE) and the RoyalSociety of Canada (The Canadian Academy of the Sciences and Humanities).He ws an IEEE Microwave Theory and Techniques Society (IEEE MTT-S)Distinguished Microwave Lecturer (2009–2011). He has held key positions inand has served on various panels and international committees including havingbeen the chair of Technical Program Committees, International Steering Com-mittees, and international conferences/symposia. He will be the general chair ofthe 2012 IEEE Microwave Theory and Techniques Society (IEEE MTT-S) In-ternational Microwave Symposium (IMS). He is currently the chair of the jointIEEE chapters of MTTS/APS/LEOS, Montréal, QC, Canada. He is an electedIEEE MTT-S Administrative Committee (AdCom) member for 2006–2015 andwas chair of the IEEEMTT-SMember and Geographic Activities (MGA) Com-mittee. He was the recipient of many awards and prizes including the first IEEEMTT-S Outstanding Young Engineer Award, the 2004 Fessenden Medal of theIEEE Canada, and the 2009 Thomas W. Eadie Medal of the Royal Society ofCanada.

Wei Hong (M’92–SM’07) was born in HebeiProvince, China, on October 24, 1962. He receivedthe B.S. degree from the Zhenzhou Institute ofTechnology, Zhenzhou, China, in 1982, and theM.S. and Ph.D. degrees from Southeast University,Nanjing, China, in 1985 and 1988, respectively, allin radio engineering.Since 1988, he has been with the State Key Lab-

oratory of Millimeter Waves, Southeast University,where he is currently a Professor and the AssociateDean of the Department of Radio Engineering.

In 1993 and from 1995 to 1998, he was a short-term Visiting Scholar with

the University of California at Berkeley and the University of California atSanta Cruz, respectively. He has been engaged in numerical methods forelectromagnetic problems, millimeter-wave theory and technology, antennas,electromagnetic scattering and RF technology for mobile communications, etc.He has authored or coauthored over 200 technical publications. He authoredPrinciple and Application of the Method of Lines (in Chinese) (Southeast Univ.Press, 1993) and Domain Decomposition Method for EM Boundary ValueProblems (in Chinese) (Sci. Press, 2005).Prof. Hong is a Senior Member of the China Institute of Electronics (CIE). He

is vice-president of the Microwave Society and Antenna Society, CIE. He hasbeen a reviewer for many technical journals including the IEEE TRANSACTIONSON ANTENNAS AND PROPAGATION and is currently an associate editor for theIEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES. He was atwo-time recipient of the First-Class Science and Technology Progress Prize ofthe State Education Commission (1992 and 1994), the Fourth-Class NationalNatural Science Prize (1991), and the First- and Third-Class Science and Tech-nology Progress Prize of Jiangsu Province. He was also the recipient of theFoundations for China Distinguished Young Investigators Award and the “In-novation Group” Award of the National Science Foundation of China.

Liang Han (S’07) was born in Nanjing, China. Hereceived the B.E. (with distinction) and M.S. degreesfrom Southeast University, Nanjing, China, in 2004and 2007, respectively, both in electrical engineering,and is currently working toward the Ph.D. degree inelectrical engineering at the École Polytechnique deMontréal, Montréal, QC, Canada.His current research interests include advanced

computer-aided design (CAD) and modeling tech-niques and development of multifunctional RFtransceivers.

Xiao-Ping Chen was born in Hubei Province, China. He received the Ph.D.degree in electrical engineering from the Huazhong University of Science andTechnology, Wuhan, China, in 2003.From 2003 to 2006, he was a Post-Doctoral Researcher with the State Key

Laboratory of Millimeter-waves, Radio Engineering Department, SoutheastUniversity, Nanjing, China, where he was involved with the design of advancedmicrowave and millimeter-wave components and circuits for communicationsystems. In May 2006, he was a Post-Doctoral Research Fellow with thePoly-Grames Research Center, Department of Electrical Engineering, ÉcolePolytechnique de Montréal, Montréal, QC, Canada, where he is currently aResearcher Associate. He has authored or coauthored over 30 referred journalsand conference papers and some proprietary research reports. He has been amember of the Editorial Board of the IET Journal. He holds several patents.His current research interests are focused on millimeter-wave components,antennas, and subsystems for radar sensors.Dr. Chen has been a reviewer for several IEEE publications. He was the re-

cipient of a 2004 China Postdoctoral Fellowship and the 2005 Open Foundationof the State Key Laboratory of Millimeter-Waves, Southeast University.

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Low Cost 60 GHz Smart Antenna Receiver Sub-System Based on Substrate Integrated Waveguide Technology