Current and Future Research Trends in Substrate Integrated Waveguide Technology

Transcription

1 RADIOENGINEERING, VOL. 18, NO., JUNE 9 1 Cuent and Futue Reseach Tends in Substate Integated Waveguide Technology Mauizio BOZZI 1, Luca PERREGRINI 1, Ke WU, Paolo ARCIONI 1 1 Deatment of Electonics, Univesity of Pavia, Pavia, Italy Poly-Games Reseach Cente, Deatment of Electical Engineeing, École Polytechnique de Montéal, Canada mauizio.bozzi@univ.it, luca.eegini@univ.it, ke.wu@olymtl.ca, aolo.acioni@univ.it Abstact. Substate Integated Waveguide (SIW) technology is the most omising candidate fo the imlementation of millimete-wave (mm-wave) integated cicuits and systems fo the next decade. Based on lana dielectic substates with to and bottom metal layes efoated with metalized holes, SIW stuctues offe a comact, low loss, flexible, and cost-effective solution fo integating active cicuits, assive comonents and adiating elements on the same substate. This ae esents an oveview of the cuent status and futue tends of academic and industial eseach on SIW technology. The histoical develoment of SIW comonents and cicuits is biefly outlined, and the cuent eseach toics ae discussed: they include the develoment of numeical techniques fo the modeling and design of SIW comonents, the investigation of novel comact and boadband inteconnects, the detemination of design solutions fo loss minimization. Futue eseach tends ae also discussed: they mainly aim at the imlementation of SIW comonents at highe fequency (6-35 GHz) and the integation of comlete Systems-on-Substate (SoS). Keywods Millimete-waves, assive waveguide comonents, System-on-Substate (SoS), Substate Integated Waveguide (SIW), Substate Integated Cicuits (SICs). 1. Intoduction The deloyment of millimete-wave (mm-wave) integation technologies is citical fo the evolution of wieless systems and alied electomagnetics in the next few yeas. In fact, a vaiety of alications has been ecently oosed in the fequency ange between 6 GHz and 94 GHz: they include wieless netwoks [1], automotive adas [], imaging sensos [3], and biomedical devices [4]. In most of these systems, the success mainly deends on the availability of a cost-effective technology, suitable to the massoduction of wieless systems. It is exected that high density integation techniques, combined with a low-cost fabication ocess, should offe the widesead solution fo mm-wave commecial alications. h ot 1 metal vias Fig. 1. Substate integated waveguide. dielectic substate ot to gound lane A omising candidate fo develoing this latfom is the substate integated waveguide (SIW) technology [5]- [9]. SIW ae integated waveguide-like stuctues fabicated by using two eiodic ows of metallic vias o slots connecting the to and bottom gound lanes of a dielectic substate (Fig. 1). The SIW scheme belongs to the family of substate integated cicuits that include othe substate integated stuctues such as substate integated image guides and substate integated non-adiative dielectic (SINRD) guides. In fact, any non-lana waveguiding stuctue including classical ectangula waveguide and coaxial lines can be synthesized into lana fom, which can be seamlessly integated with conventional inted lana cicuits such as micosti lines and colana waveguide. SIW comonents, which have been the most oula due to thei easy design and fabication, combine most of the advantages of lana inted cicuits and metallic waveguides. Simila to micosti and colana lines, SIW comonents ae comact, light, easy to fabicate, flexible, and cost effective. SIW stuctues also eseve most of the advantages of conventional metallic waveguides, namely, comlete shielding, low loss, high quality-facto and high owe-handling caability. One of the majo advantages of SIW technology is the ossibility to fabicate a comlete cicuit in lana fom (including lana cicuity, tansitions, ectangula waveguides, active comonents and antennas), using a standad inted cicuit boad o othe lana ocessing techniques. Moeove, thee is the ossibility to mount one o moe

2 M. BOZZI, L. PERREGRINI, K. WU, P. ARCIONI, CURRENT AND FUTURE RESEARCH TRENDS IN SIW TECHNOLOGY chi-sets on the same substate. Thee is no need of tansitions between elements fabicated with diffeent technologies, thus educing losses and aasitics. In this way, the concet of System-in-Package (SiP), widely adoted in the design of RF cicuits, can be extended to the System-on- Substate (SoS) [1], [11]. SoS eesents the ideal latfom fo develoing cost-effective, easy-to-fabicate and high-efomance mm-wave systems. A significant effot has been devoted to the eseach and develoment of SIW technology in the last few yeas: this widesead eseach activity has oduced novel modeling techniques fo SIW comonents, a numbe of new technological solutions, as well as SIW cicuits and systems with outstanding efomance. The inceasing numbe of scientific ublications on SIW technology confims the gowing inteest of the scientific community (Fig. ). numbe of IEEE aes yea Fig.. Numbe of ublications on the SIW in IEEE jounals (souce: ieeexloe.ieee.og). This ae esents an oveview of the cuent status and futue tends of eseach on SIW technology. The ae is oganized as follows: Sec. descibes the histoical develoment of SIW comonents; Sec. 3 outlines the most significant cuent eseach toics; finally, the futue eseach tends ae discussed in Sec. 4.. Histoical Develoment One of the fistly develoed embedded stuctues with the name of laminated waveguide [6] dates back to The SIW technology has been subsequently alied to seveal micowave and millimete-wave comonents, including active cicuits, assive comonents, and antennas. Note that the integated waveguide techniques wee oosed much ealie and it was filed as a atent [5] but ae attention was aid to this wok until about when this SIW scheme has been unified within the concet of SICs. Of couse, a much ealie vesion of embedded esonatos was also esented but it is debatable whethe we should call those stuctues as at of substate integated cicuits..1 Passive SIW Comonents Concening the assive cicuits, most of the classical micowave comonents have been imlemented in SIW technology. This solution usually emits to obtain comonents with a substantial eduction in size if comaed to classical waveguide comonents; moeove, thei losses ae lowe than in the coesonding micosti devices, esecially in the millimete-wave fequency ange, and thee ae no adiation and ackaging oblems. Among the assive comonents, filtes have eceived a aticula attention. A vaiety of diffeent filte toologies wee oosed: among them, a filte with inductive-ost oeating at 8 GHz [7] and a filte with iises oeating at 6 GHz [1] wee designed and fabicated. Subsequently, cavity filtes with cicula [13] and ectangula cavities [14] wee develoed: they emit a bette design flexibility and exhibit highe selectivity, thanks to the coss-couling that intoduces tansmission zeos. A multilayeed stuctue was adoted in [15]: the use of a two-laye substate emitted to design an ellitic filte with fou cavities oeating in C band. Comact and sue-wide band-ass filtes wee esented in [16]: due to the use of an electomagnetic band-ga (EBG) stuctue in the gound lane, a band-ass filte coveing the fequency ange GHz was designed and tested. While most of these filtes oeate in the micowave ange, filtes oeating at 6 GHz [1] and u to 18 GHz [17] wee also oosed. Besides filtes, seveal othe assive comonents have been develoed in SIW technology. Among them, two configuations of diectional coules wee oosed: the fome, based on two adjacent SIW with aetues in the common wall, was used to design 3-dB, 6-dB, and 1-dB coules [18]; the second configuation esents a cucifom shae, and was adoted to design a sue-comact 3-dB diectional coule [19]. Plana SIW dilexes oeating at 5 GHz and 5 GHz wee oosed [,1]. A magic- T [], six-ot cicuits [3], [4], and ciculatos [5], [6] wee also imlemented and exeimentally veified.. Active SIW Comonents SIW technology was also used to imlement seveal active comonents, thus exloiting the advantage of an easy integation of the active elements with the waveguide comonents. In aticula, a feedback oscillato was oosed in [7]: it oeates at 1 GHz and is based on an SIW cavity that acts as a fequency selecto as well as a feedback-couling device. Anothe toology was adoted in the Ka-Band oscillato oosed in [8], whee a Gunn diode is mounted in seies with an SIW esonant cavity. An X-band single-balanced SIW mixe was esented in [9]: thanks to the use of an SIW hybid coule with excellent efomance ove a vey boad band, the mixe exhibits an oeation bandwidth fom 8.5 to 1 GHz. A comact X-band single-tansisto amlifie with SIWbased inut and outut matching netwoks was oosed

3 RADIOENGINEERING, VOL. 18, NO., JUNE 9 3 in [3]. Convesely, fou-device owe amlifie oeating at 35 GHz was esented in [31]: it exhibits good owecombining efficiency along with a good heat sink..3 SIW Antennas In the last yeas, thee is a gowing inteest fo SIWbased antennas. Seveal configuations have been oosed: the fist SIW antenna was based on a fou-by-fou slotted SIW aay oeating at 1 GHz, obtained by etching longitudinal slots in the to metal suface of an SIW [3]. Anothe toology was the leaky-wave antennas [33]: this antenna makes use of one of the fundamental chaacteistics of this synthetic waveguide, namely, its oety to geneate leakage loss when the longitudinal sacing of the metal vias is sufficiently lage. A modified Vivaldi adiato was also oosed [34]: it consists in a dual V-tye linealy taeed slot antenna, with cente fequency at 36 GHz. whee k =ω/c is the wave-numbe at the fequency of inteest, c is the seed of light in vacuum, η is the chaacteistic imedance in vacuum, and ε is the elative dielectic emittivity of the substate. The tems A ij and B ij ae elated to the low-fequency behavio of the admittance matix, k is the esonance wave-numbe of the -th mode of the cavity obtained by shot-cicuiting the ots, and C i is elated to the couling between the i-th ot mode and the -th cavity mode. The quantities A ij, B ij, C i, and k in (1) ae fequency indeendent and ae calculated vey efficiently by the BI-RME method [4]. Once these quantities ae known, the admittance aametes of the SIW comonent can be comuted at any fequency by using (1) in a negligible time. h fictitious metal wall metal vias d s ot 3. Cuent Reseach Toics Hot toics in the cuent eseach on SIW comonents ae elated to the develoment of efficient full-wave analysis techniques fo the modeling and design of SIW comonents including multilayeed toologies, to the design of comact, boadband and low-loss inteconnects, and to the modeling and minimization of losses. h additional side ot 4 w ot 1 metal vias d (a) fictitious metal wall s ot to gound lane 3.1 Modeling and Design The modeling of SIW comonents is tyically efomed by using full-wave numeical techniques. Both commecial electomagnetic softwae and secifically develoed numeical techniques have been adoted. Electomagnetic codes based on integal-equation, finite-element o finite diffeence methods have been imlemented [35]-[39]. A aticulaly efficient numeical technique fo the modeling of abitaily shaed SIW comonents is based on the Bounday Integal-Resonant Mode Exansion (BI- RME) method [38], [39]. The BI-RME method, develoed fo the modeling of classical waveguide comonents, was oiginally alied to the modeling of SIW comonents in the lossless case. Unde the hyothesis of negligible adiation loss, the comonents can be lateally closed by fictitious metal walls without modifying thei hysical behavio (Fig. 3a). The BI-RME method allows chaacteizing SIW comonents though thei genealized admittance matix Y exessed in the fom of a ole exansion in the fequency domain, elating modal cuents and voltages of the ot modes. The geneic element of matix Y is given by 3 A P ij jk ε ε CiC jk i Yij( k) = + Bij + (1) jη k η η k k k ( ) = 1 ε w ot 1 additional side ot 3 to gound lane (b) Fig. 3. Geomety of an SIW stuctue consideed in the BI- RME analysis: (a) lossless case, with fictitious metal side-walls; (b) lossy case, with additional sideadiation absobing ots. Theefoe, the majo advantage of the BI-RME method is the ossibility to detemine in one shot the wideband exession of the fequency esonse of SIW comonents, thus avoiding eeated fequency-by-fequency electomagnetic analyses. Consequently, the BI-RME modeling of SIW comonents tyically equies few seconds on a tandad esonal comute. The fomulation of the BI-RME method fo the modeling of SIW comonents has been ecently extended to include the effect of dielectic, conducto, and adiation losses [39]. Conducto and dielectic losses have been incooated by adding the quality facto of the cavity modes in exession (1), which thus esults: Aij jkε Yij( k) = + σd Bij + Bij + jη k η kε + η 3/ 3 jkε + η P = 1 P = 1 k' k' Q 1/ ( k' + jk k' ε / Q k ε ) 1/ ( k' + jk k' ε / Q k ε ) C C i i C i C i () +

4 4 M. BOZZI, L. PERREGRINI, K. WU, P. ARCIONI, CURRENT AND FUTURE RESEARCH TRENDS IN SIW TECHNOLOGY whee Q is the quality facto of the -th cavity mode, deending on both the conductivity σ d of the dielectic medium and the conductivity σ c of the metal. Convesely, adiation loss ae included by defining additional side ots (Fig. 3b), which ae then closed with matched loads. Anothe significant advantage of the BI-RME method is the ossibility to diectly detemine equivalent cicuit models of SIW discontinuities [41]. Due to the aticula eesentation of the admittance matix given in (1), the geneic element Y ij of matix Y diectly eesents the aallel of an inductance, a caacitance, and P LC-seies esonatos (Fig. 4). Moeove, the values of the lumed elements ae analytically deived fom A ij, B ij, C i, and k. Equivalent cicuit models including losses can be deived fom (): in this case, the geneic element Y ij eesents the aallel of an inductance, a caacitance, a esistance, and P RLC-seies esonatos [4]. Y ij = L C L 1 ot 1 Y A =Y11+Y1 (a) Y B = Y 1 C 1 L C... Y C =Y+Y1 L P C P ot (b) Fig. 4. Equivalent cicuit model diectly deived fom the BI- RME analysis: (a) equivalent model of Y ij ; (b) toology of the geneic π-tye equivalent cicuit model, in the case of a two-ot comonent. The most imotant alication of the oosed method is the detemination of aametic multimodal equivalent cicuit models, whee the values of the lumed elements deend on the geometical dimensions of the comonent [41]. In fact, once a libay of equivalent cicuit models is available, the diect synthesis of a comonent can be efomed in a shot time by using conventional cicuit CAD tools, with no need of electomagnetic full wave analysis codes. 3. Comact and Wideband Inteconnects waveguide with the same cutoff fequency. The oeation bandwidth is limited to one octave (fom the cutoff fequency f 1 of the fundamental mode to cutoff fequency f = f 1 of the second mode), coesonding to the mono-modal bandwidth of the waveguide. Diffeent waveguide toologies have been ecently oosed to imove the comactness of SIW stuctues. The substate integated folded waveguide (SIFW) was oosed in [43]: a metal setum emits to fold the waveguide, thus educing the size by a facto of moe than two at the cost of slightly lage losses. The half-mode substate integated waveguide (HMSIW) was intoduced in [44]: based on the aoximation of the vetical cut of the waveguide as a vitual magnetic wall, it emits a size eduction of nealy 5%. A combination of the two techniques was also oosed [45], esulting in the folded halfmode substate integated waveguide (FHMSIW), which leads to a futhe size eduction. To imove the bandwidth efomance, some waveguide configuations have been develoed. The substate integated slab waveguide (SISW) was oosed in [46]: it consists of an SIW whee the dielectic medium is eiodically efoated with ai-filled holes, located in the lateal otion of the waveguide. This aoach allowed the design of a waveguide with a mono-modal band fom 7.5 Hz to 18 Hz, which should be extended futhe if geometical and mateial aametes ae adequately selected. The imlementation of the idge waveguide in SIW technology was oosed in [47], whee the idge was imlemented though a ow of thin, atial-height metal osts located in the cente of the wide side of the waveguide. This stuctue allowed fo achieving a 37% bandwidth enhancement. Nevetheless, the useful bandwidth of this stuctue is limited by a band-ga, which aeas when the idge osts ae thick and long. A novel class of substate integated waveguides, based on the concet of the classical idge ectangula waveguide, was oosed in [48]. The stuctue is integated in a dielectic substate with to and bottom metal layes, and comises two sided ows of full-height metal cylindes and a cental ow of atial-height metal osts, connected at thei bottom by a metal sti (Fig. 5a). Based on this stuctue, a ototye coveing the fequency band fom 6.8 GHz to 5 GHz was designed and tested (Fig. 5b). metal ost to metal laye SIW inteconnects eesent a valid altenative to micosti lines and colana waveguides, as they educe losses and adiation leakage, esecially in the mm-wave ange. Nevetheless, SIW stuctues ae limited in comactness and bandwidth. The width of the SIW is elated to the cutoff fequency of the fundamental mode, and it is smalle of a facto ε 1/ comaed to a hollow ectangula dielectic substate bottom metal laye (a) idge metal ost metal sti z

5 RADIOENGINEERING, VOL. 18, NO., JUNE 9 5 oagation constant [ad/m] f 1 =6.8 GHz mono-modal band 1st mode nd mode f =5. GHz measuement fequency [GHz] (b) Fig. 5. Ridge substate integated waveguide: (a) geomety of the stuctue; (b) simulated and measued oagation constant of the fist two modes. The oosed stuctue exhibits a mono-modal bandwidth thee times boade than classical ectangula waveguides o substate integated waveguides, and its size is half of a substate integated waveguide with the same cutoff fequency. 3.3 Loss Minimization One of the majo issues in the design of SIW comonents is elated to the minimization of losses, esecially when oeating in the mm-wave fequency ange. Thee ae thee mechanisms of loss in the SIW stuctues [39], [49]. Due to thei similaity to ectangula waveguides, SIW stuctues exhibit conducto losses due to the finite conductivity of metallic walls and dielectic losses due to the loss tangent of dielectic substate. Moeove, the esence of gas in the SIW stuctues along the side walls can detemine a adiation loss, due to a ossible leakage though the gas. The diffeent kinds of losses in substate integated waveguide inteconnects can be minimized by modifying some geometical aametes, namely the substate thickness h, the diamete d of the metal vias, and thei longitudinal sacing s (Fig. 3). The thickness h of the dielectic substate lays an imotant ole. Inceasing h (while keeing the othe dimensions unchanged) detemines a significant eduction in the conducto loss but has no effect on the dielectic loss. In geneal, adiation loss is not affected by the substate thickness (at least, as long as h is smalle than a half wavelength). Thee is a simle hysical exlanation of these henomena. With egad to the conducto loss, they deend on the suface integal of J on the metal suface, whee J eesents the electic cuent density flowing on the metal suface (moe secifically, on the to and bottom metal layes and on the suface of the metal vias). Inceasing h detemines a eduction of J ootional to h. Consequently, the conducto loss on the to and bottom sufaces scales as 1/h. On the contay, since the lateal suface of metal vias linealy inceases with h, the inceased integation suface comensates the eduction of J, and theefoe the contibution of the metal vias to conducto loss is unchanged with h. With egad to the dielectic loss, it deends on the volume integal of E (whee E eesents the electic field) ove the whole volume of the substate. Since inceasing h detemines a eduction of E ootional to h, but the volume of the substate linealy inceases with h, the dielectic loss does not vay with h. It is finally noted that the same deendence of losses on the thickness h is encounteed in the fundamental mode of classical ectangula waveguides and, in geneal, in any H- lane waveguide cicuit. Anothe imotant geometical aamete is the diamete d of the metal vias. The vaiation of the conducto and dielectic losses vesus d is limited. In aticula, the conducto loss slightly deceases when inceasing the diamete d of the vias: as aleady stated, the conducto loss deends on the suface integal of J. In this case, the contibution fom the to and bottom metal layes is actically unchanged, wheeas the contibution fom the metal vias vaies. Assuming that the cuent flowing on the suface of each via is actically unchanged, the suface inceases with d and theefoe J scales as 1/d. Since the integation suface inceases ootionally to d, the suface integal of J deceases as 1/d. Convesely, the dielectic loss is actically indeendent on the diamete d. This hysical exlanation is valid fo most cases of actical inteest: if the sacing between the metal vias is extemely small, a moe sohisticated exlanation is needed, to take into account the vaiation of the cuent distibution due to oximity effects. Finally, the adiation leakage becomes significant when the condition s/d <.5 is not met [8]. A simila behavio is obseved when vaying the longitudinal sacing s. When deceasing the value of s, the conducto loss deceases (because of the inceased metal suface) and the dielectic loss actically emains unchanged. With egads to the adiation loss, it emains small unde the condition s/d <.5 [8]. Finally, it is imotant to emak that dielectic and conducto losses exhibit a diffeent deendence on fequency [49]: it esults that the dielectic loss is tyically the most significant contibution to losses in the mm-wave fequency ange. Fo this eason, the otimization of the geomety has a maginal effect on the minimization of losses at mm-waves. In this case, a caeful selection of the dielectic mateial is extemely imotant. 4. Futue Reseach Tends The futue activities on SIW technology will be mainly devoted to the deloyment of mm-wave comonents in the fequency band between 6 and 35 GHz, to the investigation of new mateials and fabication technologies, and to the integation of comlete systems in

6 6 M. BOZZI, L. PERREGRINI, K. WU, P. ARCIONI, CURRENT AND FUTURE RESEARCH TRENDS IN SIW TECHNOLOGY SIW technology based on the System-on-Substate aoach. Of couse, the integation of SIW comonents with othe substate integated stuctues would be of geat inteest to design some innovative cicuits and systems. The imlementation of SIW comonents in the mmwave fequency ange will equie the develoment of novel stuctues, with the aim to educe the size, imove the bandwidth, and esecially minimize the losses. These stuctues can be based on multilayeed configuations, which ovide moe design flexibility while maintaining the advantage of the lana and low-cost fabication technology. Of couse, the availability of novel SIW stuctues will foste the develoment of moe efficient comonents and cicuits with advanced efomance and/o able to integate moe functions in the same comonent. At the same time, it will equie the design of novel wideband tansitions (e.g., fom micosti and colana lines to multilayeed SIW comonents). Moeove, technological constaints become moe citical when inceasing the fequency: consequently, solutions based on metalized slots instead of metal vias could mitigate this issue. The availability of SIW comonents in the fequency band between 6 and 35 GHz will oen inteesting esectives fo novel alications and new makets. The technological develoment will emit to design novel comact and boadband comonents to meet the needs of UWB systems, scientific instumentation, and low-cost commecial cicuits fo telecommunications. Among the ossible comonents of actical inteest, thee ae comact, high-ode, bimodal filtes fo sace alications, band-ass filtes with vey boad ass band fo alication in measuement instumentation, six-ot cicuits fo alication to softwae-defined adio, cicuits including active devices fo adiometes at 35 and 94 GHz, dilexes and antennas fo automotive adas at 77 and 94 GHz. Anothe eseach tend is elated to the use of new mateials and diffeent technologies fo the fabication of SIW comonents: adoting LTCC (low-temeatue cofied ceamic) o HTCC (high-temeatue co-fied ceamic) will oen comletely new scenaios fo the alicability of SIW stuctues. The use of these technologies will emit the fabication of 3D SIW comonents, which could add futhe design flexibility and lead to novel solutions with bette efomance. On the contay, the use of CMOS technology aeas to be moe citical, due to the extemely thin dielectic layes and the low-conductivity metal. Advanced mateials including smat mateials and electo-otical mateials as well as nano-stuctued mateials will lay citical oles in the design and develoment of innovative SIW cicuits and systems. The most omising eseach tend is elated to the System-on-Substate aoach. Cuently, the oduction of RF o micowave cicuits is based on the System-in- Package concet: a otion of the cicuit is integated in a chi-set, which may include oscillatos, mixes, lownoise amlifies; the emaining at is usually fabicated in inted lana technology (micosti o colana waveguides) and comises owe amlifies, selective filtes, antennas. Finally, all the comonents ae mounted on the same boad. The use of micosti o colana waveguides is aticulaly convenient below 3 GHz, but it becomes unactical at highe fequency, due to ohibitively high loss and intefeence between adjacent cicuits, and theefoe an altenative fabication technology is needed fo mm-wave systems. The use of the SIW technology fo elacing micosti o colana waveguides in mm-wave wieless systems aeas vey omising. In this way, the System-in-Package concet will be ovecome by the System-on-Substate aoach, whee all the comonents not included in the chi-set ae fabicated in SIW technology. This solution bings seveal advantages: SIW technology is cost-effective and emits to fabicate comonents with low loss and comlete shielding. Moeove, all comonents ae fabicated on the same substate, thus avoiding tansitions and inteconnections that incease losses and aasitics. Recently, comlete cicuits and fontend in SIW technology have been oosed and exeimentally veified [11],[5]. This aoach aeas to be the most omising candidate fo the imlementation of mm-wave cicuits and systems fo the next decade. 5. Conclusion This ae has esented an oveview of substate integated waveguide technology, which eesents a vey omising candidate fo the integation of mm-wave cicuits and systems in the next decade. A significant effot has been devoted in ast yeas to the develoment of active and assive SIW comonents as well as SIW antennas. Cuently, the eseach is oiented to the investigation of novel SIW stuctues, which can oeate at highe fequency with low losses and outstanding efomance. The futue tend is the integation of comlete systems in SIW technology, accoding to the System-on-Substate concet. This aoach could elace the cuent System-on-Chi and System-in-Package, and become the aadigm fo mm-wave cicuits and systems. Acknowledgements This wok was atially caied out in the famewok of COST Action IC83-RF / Micowave Communication Subsystems fo Emeging Wieless Technologies (RFCSET). Refeences [1] DANIELS, R. C., HEATH, R. W. 6 GHz wieless communications: emeging equiements and design ecommendations. IEEE Vehicula Technology Magazine, 7, vol., no. 3, [] FLEMING, W. J. New automotive sensos A eview. IEEE Sensos Jounal, 8, vol. 8, no. 11,

7 RADIOENGINEERING, VOL. 18, NO., JUNE 9 7 [3] YUJIRI, L., SHOUCRI, M., MOFFA, P. Passive millimete wave imaging. IEEE Micowave Magazine, 3, vol. 4, no. 3,. 39 to 5. [4] MIZUNO, K., WAGATSUMA, Y., WARASHINA, H., SAWAYA, K., SATO, H., MIYANAGA, S., YAMANAKA, Y. Millimete-wave imaging technologies and thei alications. In IEEE Intenational Vacuum Electonics Confeence, IVEC '7, May 7. [5] SHIGEKI, F. Waveguide Line (in Jaanese). Jaan Patent , Feb. 5, [6] HIROSHI, U., TAKESHI, T., FUJII, M. Develoment of a laminated waveguide. IEEE Tans. on Micowave Theoy and Techniques. 1998, vol. 46, no. 1, [7] DESLANDES, D., WU, K. Single-substate integation technique of lana cicuits and waveguide filtes. IEEE Tans. on Micowave Theoy and Techniques, 3, vol. 51, no., [8] XU, F., WU, K. Guided-wave and leakage chaacteistics of substate integated waveguide. IEEE Tans. on Micowave Theoy and Techniques, 5, vol. 53, no. 1, [9] DESLANDES, D., WU, K. Accuate modeling, wave mechanisms, and design consideations of a substate integated waveguide. IEEE Tans. on Micowave Theoy and Techniques, 6, vol. 54, no. 6, [1] WU, K. Towads System-on-Substate aoach fo futue. millimete-wave and hotonic wieless alications. In Poc. of Asia-Pacific Micowave Confeence, 6. [11] LI, Z., WU, K. 4-GHz fequency-modulation continuous-wave ada font-end System-on-Substate. IEEE Tans. on Micowave Theoy and Techniques, 8, vol. 56, no., [1] CHOI, S. T., YANG, K. S., TOKUDA, K., KIM, Y. H. A V-band lana naow bandass filte using a new tye integated waveguide tansition. IEEE Micowave and Wieless Comonents Lettes, 4, vol. 14, no. 1, [13] TANG, H. J., HONG, W., HAO, Z. C., CHEN, J. X., WU, K. Otimal design of comact millimete-wave SIW cicula cavity filtes. Electonics Lettes, 5, vol. 41, no. 19. [14] CHEN, X.-P., WU, K. Substate Integated Waveguide cosscouled filte with negative couling stuctue. IEEE Tans. on Micowave Theoy and Techniques, 8, vol. 56, no. 1,. 14 to 149. [15] HAO, Z. C., HONG, W., CHEN, X. P., CHEN, J. X., WU, K., CUI, T. J. Multilayeed Substate Integated Waveguide (MSIW) ellitic filte. IEEE Micowave and Wieless Comonents Lettes, 5, vol. 15, no., [16] HAO, Z. C., HONG, W., CHEN, X. P., CHEN, J. X., WU, K. Comact sue-wide bandass Substate Integated Waveguide (SIW) filtes. IEEE Tans. on Micowave Theoy and Techniques, 5, vol. 53, no. 9, [17] STEPHENS, D., YOUNG, P. R., ROBERTSON, I. D. Millimetewave substate integated waveguides and filtes in hotoimageable thick-film technology. IEEE Tans. on Micowave Theoy and Techniques, 5, vol. 53, no. 1, [18] HAO, Z. C., HONG, W., CHEN, J. X.., ZHOU, H. X., WU, K, Single-laye substate integated waveguide diectional coules. IEE Poc. Micowaves, Antennas and Poagation, 6, vol. 153, no. 5, [19] DJERAFI, T., WU, K. Sue-comact Substate Integated Waveguide cucifom diectional coule. IEEE Micowave and Wieless Comonents Lettes, 7, vol. 17, no. 11, [] HAO, Z. C., HONG, W., CHEN, X. P., CHEN, J. X., WU, K. Plana dilexe fo micowave integated cicuits. IEE Poc. Micowaves, Antennas Poagation, 5, vol. 15, no. 6, [1] TANG, H. J., HONG, W., CHEN, J.-X., LUO, G. Q., WU, K. Develoment of millimete-wave lana dilexes based on comlementay chaactes of dual-mode substate integated waveguide filtes with cicula and ellitic cavities. IEEE Tans. on Micowave Theoy and Techniques, 7, vol. 55, no. 4, [] HE, F. F., WU, K., HONG, W., TANG, H. J., ZHU, H. B., CHEN, J. X. A lana magic-t using Substate Integated Cicuits concet. IEEE Micowave and Wieless Comonents Lettes, 8, vol. 18, no. 6, [3] XU, X., BOSISIO, R. G., WU, K. A new six-ot junction based on Substate Integated Waveguide technology. IEEE Tans. on Micowave Theoy and Techniques, 5, vol. MTT-53, no. 7, [4] MOLDOVAN, E., BOSISIO, R. G., WU, K. W-band multiot substate-integated waveguide cicuits. IEEE Tans. on Micowave Theoy and Techniques, 6, vol. 54, no.,. 65 to 63. [5] D ORAZIO, W., WU, K., HELSZAJN, J. A substate integated waveguide degee- ciculato. IEEE Micowave and Wieless Comonents Lettes, 4, vol. 14, no. 5, [6] D ORAZIO, W., WU, K., Substate-integated-waveguide ciculatos suitable fo millimete-wave integation. IEEE Tans. on Micowave Theoy and Techniques, 6, vol. MTT 54, no. 1, [7] CASSIVI, Y., WU, K. Low cost micowave oscillato using substate integated waveguide cavity. IEEE Micowave and Wieless Comonents Lettes, 3, vol. 13, no., [8] C. ZHONG, J. XU, Z. YU and Y. ZHU, Ka-Band Substate Integated Waveguide Gunn Oscillato, IEEE Micowave and Wieless Com. Lettes, Vol. 18, No. 7, , July 8. [9] CHEN, J.-X., HONG, W., HAO, Z.-C., LI, H., WU, K. Develoment of a low cost micowave mixe using a boad-band Substate Integated Waveguide (SIW) coule. IEEE Micowave and Wieless Comonents Lettes, 6, vol. 16, no.. [3] JIN, H., WEN, G. A novel fou-way Ka-band satial owe combine based on HMSIW. IEEE Micowave and Wieless Comonents Lettes, 8, vol. 18, no. 8, [31] ABDOLHAMIDI, M., SHAHABADI, M. X-band substate integated waveguide amlifie. IEEE Micowave and Wieless Comonents Lettes, 8, vol. 18, no. 1, [3] YAN, L., HONG, W., HUA, G., CHEN, J., WU, K., CUI, T. J. Simulation and exeiment on SIW slot aay antennas. IEEE Micowave and Wieless Comonents Lettes, 4, vol. 14, no. 9, [33] DESLANDES, D., WU, K. Substate integated waveguide leakywave antenna: Concet and design consideations. In Asia-Pacific Micowave Conf. Poc. (APMC'5). Suzhou (China), 5. [34] CHENG, Y. J., HONG, W., WU, K. Design of a monoulse antenna using a Dual V-Tye Linealy Taeed Slot Antenna (DVLTSA). IEEE Tans. on Antennas and Poagation, 8, vol. 56, no. 9, [35] CASSIVI, Y., PERREGRINI, L., ARCIONI, P., BRESSAN, M., WU, K., CONCIAURO, G. Disesion chaacteistics of substate integated ectangula waveguide. IEEE Micowave and Wieless Comonents Lettes,, vol. 1, no. 9, [36] XU, F., ZHANG, Y., HONG, W., WU, K., CUI, T. J. Finitediffeence fequency-domain algoithm fo modeling guided-wave oeties of substate integated waveguide. IEEE Tans. on Micowave Theoy and Techniques, 3, vol. 51, no. 11, [37] YAN, L., HONG, W., WU, K., CUI, T. J. Investigations on the oagation chaacteistics of the substate integated waveguide based on the method of lines. Poc. IEE Micowave Antennas and Poagation, 5, vol. 15,

8 8 M. BOZZI, L. PERREGRINI, K. WU, P. ARCIONI, CURRENT AND FUTURE RESEARCH TRENDS IN SIW TECHNOLOGY [38] XU, F., WU, K., HONG, W. Domain decomosition FDTD algoithm combined with numeical TL calibation technique and its alication in aamete extaction of substate integated cicuits. IEEE Tans. on Micowave Theoy and Techniques, 6, vol. 54, no. 1, [39] BOZZI, M., PERREGRINI, L., WU, K. Modeling of conducto, dielectic and adiation losses in substate integated waveguide by the bounday integal-esonant mode exansion method. IEEE Tans. on Micowave Theoy and Techniques, 8, vol. 56, no. 1, [4] CONCIAURO, G., GUGLIELMI, M., SORRENTINO, R. Advanced Modal Analysis. John Wiley and Sons,. [41] BOZZI, M., PERREGRINI, L., WU, K. A novel technique fo the diect detemination of multi-mode equivalent cicuit models fo substate integated waveguide discontinuities. Inten. Jounal of RF and Micowave Comute Aided Engineeing, July 9, vol. 19, no. 4. [4] BOZZI, M., PERREGRINI, L., WU, K. Modeling of losses in substate integated waveguide by bounday integal-esonant mode exansion method. In IEEE MTT-S Intenational Micowave Symosium (IMS8). Atlanta (GA, USA), June 1-15, 8. [43] GRIGOROPOULOS, N., IZQUIERDO, B. S., YOUNG, P. R. Substate integated folded waveguides (SIFW) and filtes. IEEE Micowave Wieless Comonent Lettes, 5, vol. 15, no. 1, [44] HONG, W., WANG, Y., LAI, Q. H., LIU, B. Half mode substate integated waveguide: A new guided wave stuctue fo micowave and millimete wave alication. In Poc. Joint 31st Int. Conf. Infaed Millimete Waves 14th Int. Conf. Teahetz Electonics. Shanghai (China), 6,. 19. [45] ZHAI, G. H., HONG, W., WU, K., CHEN, J. X., CHEN, P., WEI, J., TANG, H. J. Folded half mode substate integated waveguide 3 db coule. IEEE Micowave and Wieless Comonents Lettes, 8, vol 18, no. 8, [46] BOZZI, M., DESLANDES, D., ARCIONI, P., PERREGRINI, L., WU, K., CONCIAURO, G. Efficient analysis and exeimental veification of substate integated slab waveguides fo wideband micowave alications. Inten. J. of RF and Micowave Comute Aided Engineeing, May 5, vol. 15, no. 3, [47] CHE, W., LI, C., RUSSER, P., CHOW, Y. L. Poagation and band boadening effect of lana integated idged waveguide in multilaye dielectic substates. In IEEE MTT-S Intenational Micowave Symosium Digest (IMS 8). Atlanta (GA), June 15-, 8, [48] BOZZI, M., WINKLER, S. A., WU, K. Novel comact and boadband inteconnects based on idge substate integated waveguide. In 9 IEEE MTT-S Intenational Micowave Symosium (IMS9). Boston (MA, USA), June 7-1, 9. [49] BOZZI, M., PASIAN, M., PERREGRINI, L., WU, K. On the losses in substate integated waveguides. In 37th Euoean Micowave Confeence (EuMC 7). Munich (Gemany), Oct. 8-1, 7. [5] SAMANTA, K. K., STEPHENS, D., ROBERTSON, I. D. Design and efomance of a 6-GHz multi-chi module eceive emloying substate integated waveguides. IET Micowave Antennas Poagation, 7, vol. 1, no. 5, About Authos... Mauizio BOZZI was bon in Voghea, Italy, in He eceived the Lauea degee in Electonic Engineeing and the Ph.D. in Electonics and Comute Science fom the Univesity of Pavia, Italy, in 1996 and, esectively. In he became Assistant Pofesso in Electomagnetics at the Det. of Electonics, Univesity of Pavia, whee he cuently teaches the couse of Numeical Techniques fo Electomagnetics. He held eseach ositions in Euoean and Ameican univesities, including the Technical Univesity of Damstadt, Gemany, the Univesity of Valencia, Sain, and the Polytechnical Univesity of Monteal, Canada. His eseach activities concen the develoment of numeical methods fo the electomagnetic modeling of micowave and millimete-wave comonents. D. Bozzi eceived the Best Young Scientist Pae Awad at the XXVII Geneal Assembly of URSI in, and the MECSA Pize fo the best ae esented at the Italian Confeence on Electomagnetics in. Luca PERREGRINI was bon in Sondio, Italy, in He eceived the Lauea degee in Electonic Engineeing and the Ph.D. in Electonics and Comute Science fom the Univesity of Pavia, Pavia, Italy, in 1989 and 1993, esectively. In 199, he joined the Det. of Electonics, Univesity of Pavia, whee he is now an Associate Pofesso in Electomagnetics. His main eseach inteests ae in numeical methods fo the analysis and otimization of waveguide cicuits, fequency selective sufaces, eflectaays, and inted micowave cicuits. He co-authoed the textbook Fondamenti di Onde Elettomagnetiche (Milano, Italy, McGaw-Hill Italia, 3). Pof. Peegini was an Invited Pofesso at the Polytechnical Univesity of Monteal, Monteal, Quebec, Canada in 1,, and 4. He was a consultant of the Euoean Sace Agency and of some Euoean telecommunication comanies. Ke WU is Pofesso of Electical Engineeing, and Canada Reseach Chai in RF and millimete-wave engineeing at the Ecole Polytechnique (Univesity of Monteal). He has been the Diecto of the Poly-Games Reseach Cente and the Founding Diecto of the Cente fo Radiofequency Electonics Reseach of Quebec. He has authoed o coauthoed ove 67 efeed aes, and a numbe of books/book chates and atents. D. Wu has held key ositions in and has seved on vaious anels and intenational committees including the chai of technical ogam committees, intenational steeing committees and intenational confeences/symosia. In aticula, he will be the geneal chai of the 1 IEEE MTT-S Intenational Micowave Symosium. He has seved on the editoial/eview boads of many technical jounals, tansactions and lettes as well as scientific encycloedia including editos and guest editos. D. Wu is an elected IEEE MTT-S AdCom membe fo 6-1 and seves as the chai of the IEEE MTT-S Tansnational Committee. He was the eciient of many awads and izes including the fist IEEE MTT-S Outstanding Young Enginee Awad and the 4 Fessenden Medal of the IEEE Canada. He is a Fellow of the IEEE, a Fellow of the Canadian Academy of Engineeing (CAE) and a Fellow of the Royal Society of Canada (The Canadian Academy of the Sciences and Humanities). He is an IEEE MTT-S Distinguished Mico-wave Lectue fom Jan. 9 to Dec. 11.

9 RADIOENGINEERING, VOL. 18, NO., JUNE 9 9 Paolo ARCIONI eceived the Lauea degee in Electonic Engineeing fom the Univesity of Pavia, Italy, in In 1974 he joined the Det. of Electonics, Univesity of Pavia, whee he cuently teaches micowave theoy as a Full Pofesso. In 1991, he was a Visiting Scientist at the Stanfod Linea Acceleato Cente (SLAC), Stanfod, CA, whee he woked in cooeation with the RF Gou to design otimized cavities fo the PEP II Poject. Fom 199 to 1993, he collaboated with the Istituto Nazionale di Fisica Nucleae (INFN), Fascati, Italy, on the design of the acceleating cavities fo the DAΦNE stoage ing. In 4, he became Head of the Det. of Electonics, Univesity of Pavia. His eseach activity has concened the design of comensated stuctues fo linea acceleatos, the develoment of micowave equiment fo EPR, the investigation of feite tuning of owe magnetons, the study of a novel numeical technique (the Bounday Integal Resonant Mode Exansion, BI RME, method) fo the modeling of waveguide and micosti cicuits, and ecently the modeling of lana comonents on semiconducto substates and of integated stuctues fo millimete-wave cicuits. RADIOENGINEERING REVIEWERS June 9, Volume 18, Numbe MEDVED-ROGINA, B., Univesity of Zageb, Coatia MIKKELSEN, J., Aalbog Univesity, Denmak NICOLE, P., Thales Systemes Aeootes S.A., Fance PETRŽELA, J., Bno Univ. of Technology, Czechia PIKSA, P., Czech Technical Univesity in Pague, Czechia POLÍVKA, M., Czech Technical Univesity in Pague, Czechia POUPA, M., Univesity of West Bohemia, Pilsen, Czechia PRADES, C. F., Cente Tecnologic de Telecomunicacions de Catalunya, Sain PROKOPEC, J., Bno Univ. of Technology, Czechia RAIDA, Z., Bno Univesity of Technology, Czechia RIDZOŇ, R., Technical Univesity of Košice, Slovakia SCHEJBAL, V., Univesity of Padubice, Jan Pene Tansot Faculty, Czechia SMUTNÝ, L., VŠB - Technical Univesity of Ostava, Czechia SYROVÁTKA, B., Czech Technical Univesity in Pague, Czechia ŠEBESTA, J., Bno Univ. of Technology, Czechia ŠEBESTA, V., Bno Univ. of Technology, Czechia ŠKVOR, Z., Czech Technical Univesity in Pague, Czechia ŠOCHMAN, J., Czech Technical Univesity in Pague, Czechia ŠUBRT, O., Czech Technical Univesity in Pague, Czechia URBANEC, T., Bno Univ. of Technology, Czechia VALERIO, G., La Saienza Univesity of Rome, Italy VÁGNER, P., Bno Univ. of Technology, Czechia VEGNI, A. M., Univesity of Roma Te, Italy VOLIOTIS, S., Technological Educational Institute of Chalkida, Geece VRBA, K., Bno Univ. of Technology, Czechia WIESER, V., Univesity of Žilina, Slovakia WILFERT, O., Bno Univ. of Technology, Czechia WRULICH, M., Vienna Univesity of Technology, Austia YANNOPOULOU, N., Democitus Univesity of Thace, Geece YO-SUNG, H., Gwangju Institute of Science and Technology, South Koea ZEZULA, R., Bno Univ. of Technology, Czechia ZOVKO-CIHLAR, B., Univesity of Zageb, Coatia ZVÁNOVEC, S., Czech Technical Univesity in Pague, Czech