Bai Thuc Hanh HFSS

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Thc hnh thit k anten vi di

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<ul><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>THIT K, M PHNGV KHO ST CC THNG S K THUT CA ANTEN VI DI</p><p>I.MC CHGip cho sinh vin hiu c vai tr,v tr ca anten trong cc h thng </p><p>truyn thng v tuyn. Sinh vin c tin hnh m phng kho st cc thng s k thut ca anten bng phn mm m phng HFSS, tnh ton thit k v ch to anten vi di hot ng di tn yu cu, s dng my phn tch mng (network analyzer) o c kho st cc thng s k thut ca mt s anten mu.II. C S L THUYT</p><p>Anten l thit b quan trng khng th thiu trong mi h thng truyn thng khng dy. N l thit b chuyn i sng in t rng buc trong cc h nh hng thnh sng in t lan truyn trong khng gian t do v ngc li. Anten v ng dy dn (feeder) ng vai tr l thit b ghp gia cc mch in t v khng gian t do, feeder l b phn giao tip gia anten v mch in t. Ng vo ca feeder phi phi hp tr khng vi my pht, cn antenna pht nhn nng lng t my pht qua feeder v bc x ra khng gian. Ngoi vic phi hp tr khng yu cu i vi anten cn phi p ng v li v phng hng bc x.</p><p>Hin nay, ty thuc vo mc ch s dng ca cc h thng truyn thng v tuyn ngi ta s dng rt nhiu loi anten khc nhau, nh anten parabol vi li v tnh nh hng cao thng c s dng trong truyn hnh, thng tin vi ba, thng tin v tinh... cn u cui thng s dng cc loi anten nh nh anten Yagi,anten dy,... v c bit cng vi s pht trin mnh m v cng ngh ca cc u cui di ng th anten vi di ngy cng c s dng rng ri v khng ngng ci tin p ng nhu cu ca ngi s dng.</p><p>Anten vi di (hay anten mch in) c kch thc rt nh c cu to gm mt lp kim loi l mt bc x, mt lp kim loi khc gi l mt t (mn chn kim loi ), mt lp in mi gia hai lp kim loi trn v b phn tip in. Anten vi di c nhiu hnh dng nh hnh trn,hnh tam gic, hnh vung, hnh ch nht... trong , loi ph bin nht c kt cu hnh ch nht v c hng tnh, li cao ng thi d kt hp vi cc mch in t trn cng mt mch in.</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>1</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>Cc thng s k thut c bn ca anten- Tn s cng tc ca anten l tn s cng hng ca anten. Anten lun lm </p><p>vic ch cng hng v khi cng sut bc x ca anten l ln nht.- H s nh hng ca anten theo hng cc i c nh ngha bng t </p><p>s cng trng bc x ti mt v tr trn hng v cng trng bc x ca mt anten chun cng v tr tng ng (D). H s tng ch ( li) ca anten (G=e.D), trong e l hiu sut bc x ca anten;</p><p>- Tr khng vo ca anten : ZA = RA + jXAKhi kt ni anten vi feeder cn ch ti iu kin phi hp tr khng,Thng thng tr khng c tnh ca feeder l R0 ph hp tr khng th ZA = R0</p><p>- H s tn hao RL (dB) nh gi mc phn x ca sng ti im kt ni anten vi feeder</p><p>- H s sng ng SWR nh gi mc khng phi hp tr khng gia anten v feeder.</p><p>Trong :W l chiu rng mt bc x;L l chiu di mt bc x;h l b dy ca lp in mi;Wg l chiu rng ca mt phng t;Lg l chiu di ca mt phng t.</p><p>III. TNH TON, M PHNG V KHO ST CC THNG S K THUT CA ANTEN</p><p>Anten vi di hnh ch nht c cu to gm mt bc x, mt phng t v lp in mi gia 2 mt kim loi trn. Kch thc ca mt bc x, chiu cao v h s in mi l nhng thng s quyt nh tn s cng hng ca anten, nn chng phi c la chn v tnh ton chnh xc.</p><p>Chn vt liu ch to anten l tm mch in hai mt c h s in mi v dy l: r = 4.5; h = 1.6 mm;Tnh ton kch thc ca anten vi di lm vic tn s:Gii tn GSM: f0= 1900 MHz</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>2</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>Chiu rng ca mt bc x c tnh theo cng thc:</p><p>W = 2</p><p>12 0+rf</p><p>c 48 (mm)</p><p>c = 3x108 m/sVi c = 3x108 m/s ( c l vn tc nh sng), f0 l tn s cng hng ca anten, </p><p>r l h s in mi ca lp in mi.H s in mi hiu dng reff ph thuc c vo cc kch thc (W , h) v n </p><p>c xc nh theo cng thc:</p><p>reff = 1</p><p>2r + + </p><p>12</p><p>r 1/2</p><p>1 12wh </p><p>+ Thay s vo ta c reff 4.22</p><p> di hiu dng ca anten c xc nh theo cng thc:</p><p>Leff e2 o r ff</p><p>cf </p><p>Thay s vo ta c Leff 0.038 tng di L c tnh theo cng thc:</p><p>L = e</p><p>e</p><p>w( 0.3)( 0.264)0.412 . w( 0.258)( 0.8)</p><p>r ff</p><p>r ff</p><p>hh</p><p>h</p><p>+ +</p><p> + =</p><p> Thay s vo ta c L 0.76(mm) di thc ca mt bc x c tnh bi cng thc:</p><p>L = Leff - 2L =0.038 - 2x0.76x10-3 0.766 (mm)Kch thc ca mt phng t ( Wg v Lg ) c xc nh theo cng thc:</p><p>Wg 6h + W Wg 6x1.6 + 48 58(mm) Lg 6h + L </p><p> Lg 6x1.6 +36 46 (mm)3.1. Cc phng php tip in cho anten vi dia. Tip in bng cp ng trc (hnh 1)</p><p>Trong phng php tip in cho anten vi di bng cp ng trc th li cp c hn tip xc vi mt bc x, v cp tip xc vi mt phng t.V tr tip in tt nht c tnh ton v xc nh c ta ( L/4, W/2)</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>3</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>Phng php tip in ny c cc u im l d thc hin v khng c bc x ph.b. Tip in bng ng truyn vi di</p><p>Trong k thut tip in ny, mt di dn c kt ni trc tip n cnh ca mt bc x anten vi di. Di dn c thit k trn cng b mt vi mt bc x.</p><p>Chiu rng ca di dn nh hn rt nhiu so vi kch thc ca mt bc x. V tr tip in c ta (L/2, 0).</p><p>Kch thc ca di dn (Wf ; Lf ) c xc nh nh sau:Tr khng c tnh ca ng truyn l: Zo = 50Chiu rng ca di dn c tnh theo cng thc sau:</p><p>Wf = 12 0.611 ln(2 1) ln( 1) 0.39</p><p>2r</p><p>r r</p><p>h B B B </p><p> + + </p><p>Trong : B = 0377</p><p>2 rZ </p><p>= 5.58Mi quan h gia chiu di v chiu rng: Lf /Wf = 3.96</p><p>IV. HNG DN S DNG PHN MM M PHNG HFSSHFSS ( Hight Frequency Structure Simulator ) l phn mm m phng </p><p>trng in t theo phng php ton sng (full wave) m hnh ha bt k thit b th ng 3D no. u im ni bt ca HFSS l c dao din ngi dng ha,tch hp m phng, o ha, m hnh ha 3D v t ng ha (t ng tm li gii) trong mt mi trng d dng hc, trong li gii cho cc bi ton in t 3D thu c mt cch nhanh chng v chnh xc. Ansoft HFSS s dng phng php phn t hu hn (Finite Element Method,FEM ), k thut chia li thch nghi (adaptive meshing ) v k thut ha. Ansoft HFSS c th c s dng tnh ton cc tham s chng hn nh: h s tn hao, tn s cng hng,gin hng tnh,tr khng vo...HFSS l mt h thng m phng tng tc,trong phn t mt li c bn l mt t din. iu ny cho php bn c th tm li gii cho bt k vt th 3D no. c bit i vi cc cu trc dng cong phc tp. Ansoft l cng ty tin phong s dng phng php phn t hu hn (FEM ) m phng trng in t bng cc k thut nh: phn t hu hn,chia li thch nghi...Ansoft HFSS cung cp mt giao din trc gic v d dng s dng pht trin cc thit b RF th ng.</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>4</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p> Tm tt qu trnh m phng bng phn mm HSFF m phng mt anten bt k v c bn ta thc hin cc bc sau:</p><p> Chn HFSS \ Solution Type \ Driven Terminal Chn n v: #D Modeler \Units, chn mm</p><p> Da vo cc cng c trn thanh cng c v cu trc ca anten vo giao din lm vic</p><p> To port cp ngunChn mt cp ngun, sau vo HFSS \ Excitation \ Assign - Nu cp ngun bng probe th chn Wave Port</p><p> - Nu cp ngun bng ng vi di th chn Lumped Port Khai bo cc mt bc x ( thng khai bo cho mt phng t ): Chn mt </p><p>bc x, sau vo HFSS \ Boundaries \ Assign \ Perfect E To khng gian bc x cho anten- V mt Box bao trm c anten, thng thng khong cch t ra anten n mt Box khong bc sng cng hng cn thit, sau vo:</p><p> HFSS \ Boundaries \ Assign \ Radiation- Chn cc mt ca Box pha m anten c bc x</p><p>- Chn HFSS \ Radiation \ nsert Far Field Setup \ Infinite Sphere- Mn hnh hin ln bng pha Far Field Radiation Sphere Setup- Nhp cc thng s mnh mun v nhn OK</p><p> Khai bo tn s cng hng mong mun, s bc lp v sai s ln nht chp nhn c: HFSS \ Analysis Setup \ Add Solution Setup</p><p> - Solution Frequency: nhp vo tn s cng hng mong mun- Maximum Number of Passed: s bc lp ti a ca m phng- Maximum Delta S Per Pass: sai s chp nhn c, cng nh cng chnh </p><p>xc. Chng trnh m phng s chy cho n khi sai s tnh ton nh hn hoc bng delta S. Khi xem nh m phng chnh xc v c hi t ( Converged). Nu chy ht tt c cc bc lp m vn khng c sai s no nh hn delta S, chng trnh cng s t ng dng li. Khi qu trnh m phng s khng hi t v cho kt qu khng chnh xc. Mun khc phc ta phi tng gi tr delta S ln hoc l tng s bc lp ln nhn c kt qu chnh xc. Tuy nhin nu sai s tnh ra ngay nhng bc lp u tin nh hn Delta S th kt qu nhn c </p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>5</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>cng khng ng tin. trnh hin tng ny ta phi gim Delta S tng s bc lp ca chng trnh. Thng thng nu chng trnh chy nhiu hn 5 bc lp v c hi t th s nhn c kt qu chnh xc.</p><p> Khai bo vng tn s kho st ( xung quanh tn s trung tm)Vo HFSS \ Analysis Setup \ Add Sweep</p><p> Sau khi thc hin tt c cng on trn, ta vo HFSS \ Validation check kim tra li thit k. Nu khng c li, vo HFSS \ Analyze v bt u chy m phng.</p><p> Hin th cc kt qu m phng- vo HFSS \ Results \ </p><p>V. CC THNG S M PHNG TN S 1900Ghz5.1. Thit k ng ten vi di- Khi ng chng trnh: Program =&gt; Ansoft =&gt; HFSS11 =&gt; HFSS11</p><p>- Thit lp thng s: </p><p>+ Tool =&gt; Option =&gt; HFSS option</p><p>Ti khung General tch chn nh sau:</p><p>+ Tool =&gt; Options =&gt; Modeler options</p><p>Trong khung 3D Modele options mc Operation chn Automatically cover closed polylines</p><p>Trong mc Drawing chn edit properties of new primitivesGio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>6</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>+ Moderler =&gt; units =&gt; Select units: mm</p><p>+ HFSS =&gt; Solution type =&gt; Chn Driven Terminal</p><p> y chn gi quyt bi ton tn s lm vic f0 = 1900 MHZ</p><p>- Thit k mt phng t: Draw =&gt; box ( t)</p><p> + Thng s thit k lp t</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>7</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>+ Thit lp mt phng t:</p><p>Edit =&gt; select =&gt; face</p><p>HFSS =&gt; Boundaries =&gt; Asign =&gt; Finite Conductivity Ok</p><p>- Thit k lp in mi: Draw =&gt; box ( in mi)</p><p> Thng s thit k lp in mi </p><p>- Thit k mt bc x =&gt; box ( bc x)</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>8</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p> Thng s thit k lp Mt bc x </p><p>- Thit k lp line =&gt; box ( line)</p><p>Thng s thit k lp Line</p><p>- Thit k im cp ngun cho ng vi di</p><p> v ngun ta vo Draw=&gt;Rectangle (v hnh ch nht vung gc v tip xc mt ngoi Feed Line)</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>9</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p> Thng s thit k lp Ngun </p><p>Thit lp cp in: HFSS=&gt;Excitations=&gt;Asign=&gt;Lumped Port (Nu thy Feed Line bn mc Conducting Objects c ngha c tip im, nhn Ok cp ngun)</p><p>- Thit k lp khng gian: Draw =&gt; box ( khng gian)</p><p> + Thng s thit k lp Khng gian </p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>10</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>+ mt bc x: Kch chn ln lt 4 mt bn v mt trn ca mt bc x ri thc hin: HFSS=&gt; Boundaries=&gt;Assign=&gt; Radiation </p><p>+ Thit lp hng bc x: HFSS=&gt;Radiation=&gt;Insert Far Field Setup=&gt;Infinte=&gt;Ok</p><p>+ Thit lp tn s lm vic: HFSS=&gt; Analysis Setup=&gt;Add Solution Setup</p><p> y ta thit lp tn s lm vic nh chn l : 1900 MHZAdd Frequency Sweep</p><p> Ta c Star: 1.5GHZ, Stop : 2.4 GHZ , cn Step Sto</p><p>+ Thit lp gii hn tn s qut: HFSS=&gt;Analysis Setup=&gt;p l : 10 MHZ</p><p> Sau Sweep Type chn: Fast &gt; chn Ok To</p><p>5.3. Thng s thit k ng ten cp ngun bng cp ng trc- Thng s thit k lp t (tng t nh trn)- Thng s thit k lp in mi (tng t nh trn)- Thng s thit k lp Mt bc x (tng t nh trn)- Thng s tip in trn </p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>11</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>- Thng s tip in di</p><p>- Thng s vng ngoi</p><p>- Thng s thit k lp Cp ngunGio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>12</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>- Thit k lp khng gian: Draw =&gt; box ( khng gian)</p><p> + Thng s thit k lp Khng gian </p><p>+ mt bc x: Kch chn ln lt 4 mt bn v mt trn ca mt bc x ri thc hin: HFSS=&gt; Boundaries=&gt;Assign=&gt; Radiation </p><p>- Thit lp cc thng s</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>13</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>+ Thit lp hng bc x: HFSS=&gt;Radiation=&gt;Insert Far Field Setup=&gt;Infinte=&gt;Ok</p><p>+ Thit lp tn s lm vic: HFSS=&gt; Analysis Setup=&gt;Add Solution Setup</p><p> y ta thit lp tn s lm vic nh chn l : 1900 MHZAdd Frequency Sweep</p><p> Ta c Star: 1.5GHZ, Stop : 2.4 GHZ , cn Step Sto</p><p>+ Thit lp gii hn tn s qut: HFSS=&gt;Analysis Setup=&gt;p l : 10 MHZ</p><p> Sau Sweep Type chn: Fast &gt; chn Ok To</p><p>VI . Kt qu m phng6.1. Kt qu m phng thit k ng ten vi di tn s 900Hnh m phng 3D</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>14</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>Tn s cng hng:</p><p> th smith:</p><p> li:</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>15</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>nh gi v qu trnh v kt qu m phng:- suy hao khng ln- Kt qu m phng t c kt qu gn st vi tn s 900- Hnh dng th t vi yu cu ra- Qua nhiu ln cn chnh cho thy: vi tn s kh cao l 900 th kt qu kh chnh xc,cn tnh ton t m, chnh sa hp l mi c th t kt qu tt nht6.2. Kt qu m phng thit k ng ten cp ngun bng cp ng trc tn s 1900GhzHnh m phng 3D</p><p>Tn s cng hng:</p><p> th smith: </p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>16</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p> th 3D Polar Plot</p><p>nh gi kt qu m phng thit k ng ten cp ngun bng cp ng trc:- Tnh ton ta t phc tp v t cn sa hn so vi thit k ng ten vi di- Cho hnh dng m phng t chun t cn chnh hn- Tn s t c kh st vi tn s 1900khz- Trn kt qu ta thy suy hao vn cn kh lnVII. KT QU S DNG MY PHN TCH MANG CHO ANTEN VI DI7.1.Cung cp ngun v nhn nt khi ng cho my phn tch mng E5061A7.2. Kt ni ph kin cao tn chun MSA Port 1 ca my phn tch mng E5061 A Agilent E5061 RF Network Analyzer7.3. H s phn x ( S11):</p><p>Gio vin hng dn: TH.S L Th Kiu Nga TH.S Nguyn Th Minh </p><p>17</p></li><li><p>Bo Co Thc Hnh Chuyn Ngnh in T Vin Thng </p><p>H s suy hao im phn x S11 = -13.437dB </p><p>Tn s cng hng im phn x f=970.30464MHz</p><p>7.4. th Smith Chart uc hin th:</p><p>Tr khng o uc trn th l =47.41 </p><p>7.5. H s sng ng SWR:</p><p>Ti im S11 xc nh tn f= 969.31MHz</p><p>H s sng ng =1.52 </p><p>Gio vin hng dn: TH.S L Th Kiu Nga...</p></li></ul>