Design of Substrate Integrated Waveguide Pass Filter at ...

1 Design of Substrate Integrated Waveguide pass Filter at [33-75] GHz Band Ahmed Rhbanou #1, Seddik Bri * # Department of Mathematics, FSM, Moulay Ismail University Meknes, 50000, Morocco 1 * MIN, Electrical Engineering Department, ESTM, Moulay Ismail University Meknes, 50000, Morocco Abstract This article presented the Design of two filters SIW ( Substrate Integrated Waveguide ) in two different bands. Their conceptions were made by two different topologies. The first SIW Filter with circular inductive post in the band [33-50] GHz on an RT / Duroid 5880 Substrate permittivity , the simulated results of this Filter have shown that the insertion loss lower than dB within bandwidth around GHz and the return loss is better than -15 dB between GHz and GHz. The second SIW Filter with iris in the band [50-75] GHz on an NY9217 (IM) Substrate permittivity , the simulated results of this Filter have shown that the insertion loss lower than dB within 19% bandwidth around 62 GHz and the return loss is better than -15 dB between 60 GHz and GHz.

2 The compatibility with planar circuits is provided via a specific microstrip transition (microstrip tapered transitions). Keyword-Rectangular Waveguide , Substrate Integrated Waveguide , Microwave Filters, Transition, SIW-Microstrip Technology I. INTRODUCTION A High selectivity, low insertion loss, small size and limited cost are so many essential questions in the Design and the manufacturing of microwave circuits. Unfortunately, the traditional technology, either planar or non-planar, is incapable to provide all these characteristics at the same time. In fact, the rectangular waveguides present low insertion losses and good selectivity. However, their production is costly and their integration with other planar circuits requires a specific transition. For planar circuits have a low quality factor, but they have a good compatibility and low cost manufacturing. These constraints led us to use the SIW technology to combine the respective advantages of the technologies previously mentioned.

3 This concept associates the use of planar technology microstrip and the functioning of cavities in which are going to exist volume modes [1]. Technically, cavities are included in the substratum and are delimited for the upper and lower faces by the metal plane and for the side faces by rows of metallic holes. This vias have a diameter and spacing small to appear as electric walls [1-5]. However, the change of electrical walls by metallic holes implies that certain modes cannot resonate. The SIW ( Substrate Integrated Waveguide ) structures have been of great interest and with a specific transition that this technology is compatible with some planar technologies [6]. However, the SIW has been applied successfully to the conception of planar compact components for the microwave and millimeter wave applications. Such as filters [2, 5, 8, 9, 11], numerous applications were made on SIW filters for millimeter and sub-millimeter [5, 8, 9, 11, 12].

4 The results show that the quality factor greater than what can be obtained with planar technology. II. Design OF THE SIW TECHNOLOGY A Substrate Integrated Waveguide (SIW) is made of metallic via-hole arrays in the Substrate between top and bottom metal layers replacing the two metal sidewalls are shown in Fig. 1. Ahmed Rhbanou et al. / International Journal of Engineering and Technology (IJET)ISSN : 0975-4024 Vol 6 No 6 Dec 2014-Jan 20152815 The dicenter. WThe wP < 4D wThe psimilar. Iconventio Genermatch thewidth WMwe used t imension D coWSIW Is the reawidth and the lwith r relativepropagation prIn particular, onal rectangulIII. Tally, a microse impedance bM) and dimenthe tapered traorresponds toal distance betwength of the Se permittivity roperties in ththe electromalar Waveguide (a) Fig. 2 THEORETICAL strip transitionbetween a micnsions (width Wansitions as shF the diameter ween the two SIW guide wa[1-3]: WLeffhe SIW and agnetic field e filled with thfc 2.

5 (a) SIW GuideSTUDY OF BAn is used to incrostrip line aWT and lengthhown in Fig. 3 Fig. 1. SIW Fig. 1. SIW Guidof vias and Prows of vias. as found by eqWSIWeff LSIWff0 in the convedistribution ishe same dieleceffWcc210 e. (b) Equivalent AND pass FILT nterconnect SIand the SIW. Th LT) of a tran3. Guide with taperde P the distance quations 1 metals TE10 [1], thctric of width r rectangular waveTER AND PROPIW to the planThe physical cnsition are wired transitions between two d 2 provided thllic rectangulahe SIW guide Weff. (b) eguide OSED TRANSITnar transmissiocharacteristicsidely detailed adjacent viashat P < 0 ( r/ar waveguidee is similar toTIONS on lines. She s of microstripin [4, 6]. In t s center in /2)1/2 and e are very that of a is used to p line (the this study, (1) (2) (3) Ahmed Rhbanou et al. / International Journal of Engineering and Technology (IJET)ISSN : 0975-4024 Vol 6 No 6 Dec 2014-Jan 20152816 The microwave band- pass filters are presented by an equivalent circuit [7].

6 This circuit consists of impedance inverters and parallel resonant circuits. The number of the resonators or the order of the Filter is determined by equation 4 applicable in the case of Chebyshev synthesis [7]. (4) Where n is the order of the Filter , LAs is the level of out-of-band rejection in the pulsation s and LAr is the maximal amplitude of the undulation. s is the frequency of rejection high, found by the equation of the transformation of frequency [7], whose cut-off frequency is c=1 rad/s. The resonators in equivalent circuit are modeled by inductance and capacitance in series [7]: FBWgZCLiCSiSi0001 ni 1 (5) Where FBW is the relative bandwidth of the Filter , 0 is the center angular frequency and Z0 is the source impedance.

7 The coupling coefficients between resonators are provided by impedance inverters Ki,i+1(0 i n) [7]. ggLZKCSFBW101001,0 (6) ggLLKiiiSSiCiiFBW1101, 11 ni (7) ggLZKnnCSnnnnFBW1011, (8) On the other the Waveguide filters are formed with resonator distributed elements interconnected by impedance inverters or admittance. The distribution of the electric field in the SIW has characteristics of dispersal similar to the mode of the Waveguide . The conception of Filter SIW uses the same process the conception of a Filter Waveguide . The equivalent circuit of the band- pass Filter SIW is presented by impedance inverter and phase shifts [8].

8 The impedance inverters Ki,i+1(0 i n) are given by the formulas in [9, 11]: ggZKC1001,02 (9) ggZKiiCii101,12 11 ni (10) ggZKnnCnn101,2 (11) Where gi(0 i n+1) Are the coefficients of Chebyshev, c=1 rad/s is the cut-off frequency. is the fractional bandwidth [9], defined by the guided wavelength g1, g2 for cutoff frequencies f1 low and f2 high bandwidth, the guided wavelength g0 of the center frequency f0: 021ggg (12) In hybrid networks inverters are a broadband [9], the equivalence relations with the inverters are represented by the following relationship 13, as in [11]: ZKZKZX iiiiii01,1201,01, (13) The phase shifts or the electrical lengths of the resonators are determined in [9]: 1,,121 iiiii ni 1 (14) Ahmed Rhbanou et al.

9 / International Journal of Engineering and Technology (IJET)ISSN : 0975-4024 Vol 6 No 6 Dec 2014-Jan 20152817 The totopology The SIof circula Circulas shownWhere WdSIWi (i=0waveguidWhere i The Scoupling,widths WIris is in Fig. of y with circular IW Filter withar post dSIWi wlar post is reprn in Fig. 5. WSIW Is the wi0,1,2,..n) is de [10, 11]. Thi (1 i n) areSIW Filter wit, That is an oWSIWi (i=0,1, b SIW have beinductive posh circular induwhich delimit tresented by a idth of the wadetermined bhe lengths LSIe the electricalth iris is influopening in ) the resoy a diagram (oWith ii,1 een extensivelst. uctive post is ithe cavities ofFig. 4. SIW fidiagram (or cFig. 5. Typical aveguide, dSIWby the equatioIWi (i=1,2,3,..SILl lengths of theuenced by th wall betweenonators) as shoFig. or circuit) con i1tanly studied. Foinfluenced byf the Filter as sfilter with circularcircuit) consistequivalent circuiWi the diameteon 13 and ) the resonat 20igIWi e lengths LSn two adjacenown in Fig.

10 SIW Filter witnsisting of two ZXii0,12 1or our study wy the lengths Lshown in Fig. r inductive post ting of two eqt for circular poster of circular e abacus of thtors are determi ni 1 IWi (i=1,2, cavities. Thth iris o equivalent cni 1 we used the LSIWi the caviti4. quivalent capat post. The diahe estimated dmined by the e ..,n) the resonhis type of opecapacitances Xtopology withies and by the acitances XS anameter of circdiameter in reequation 15, anators and alsening is calle XS and self XPh iris and e diameter nd self XP ular posts ectangular as in [9] : so by the d iris (the as shown (15) Ahmed Rhbanou et al. / International Journal of Engineering and Technology (IJET)ISSN : 0975-4024 Vol 6 No 6 Dec 2014-Jan 20152818 Where Wcavities SThe widtabacus ofA. SIW FThis mmThe stfrequencyWeff = wplanar tra50 micSIW, as tThe padeterminThe micrThe dimeThe struc This sin the freWSIW is the widSIW inductiveths WSIWi (i=0f the estimatedFilter with Cirfilter is designm.))