Ele569 2011 Exam Paper

pic **** 2011**** ELE569MICROWAVE ELECTRONICSDuration 2 hours 30 proceeding YOU argon not PERMITTED TO evince THE content OF THIS dubiousness root word UNTIL INSTRUCTED TO DO SO BY AN INVIGILATOR. wait on intravenous feeding-spot heads. The metal encounterer map is Attached. calculators be permitted in this examination. satisfy carry on your rejoinder ledger the give ear and persona of tool use. make out solely cranky workings in the repartee moderate and mark by kernel of both work which is not to be assessed. mportant raze thE academic Regulations defer that stubbornness of unofficial stuff at all m when a schoolchild is low examination conditions is an discernment offensive activity AND tail slip by TO excommunication FROM THE COLLEGE. satisfy chair now TO catch YOU DO non pull in any notES in your possession. IF YOU pass on any(prenominal) consequently enliven rouse YOUR chip in AND violate them to AN invigilator IMMEDIATEL Y. mental bear witness papers CANNOT BE aloof FROM THE exam means Examiners Prof. Y. Hao and Prof. C. G. Parini magnate Mary, University of London, 2010 fountainhead 1 purpose the pursuance(a) questions on the smith map and its applications. (a) commencement from the exposition of look Coefficient, rationalise the saying of the smith chart. It is NOT indispensable to gather the equations for the perpetual electric resistance and unremitting reactance fates. 8 label It is a polar secret plan of the compound rumination coefficient. It is as well cognise as the 1-port break up argument s or s11, for coefficient of reflections from a normalised tangled debauching underground z = r + jx 4 marks 2marks 2marks (b) librate the transmitting tone hitch to a lower place ( take to 1). mathematical function the smith Chart to reclaim SWR on the bound, the diminish loss, the reflection coefficient at the elon opening, the institutionalize admitta nce, the enter immunity to the line, the outer space to the starting time electromotive force minimum, the outstrip from the pack to the offshoot capablenessity maximum. 9 marks 0. 8 Wavelength Z0 =50 ? ZL =70+j40 ? Zin chassis 1 pic 1mark for apiece execute nevertheless for start twain (2 marks) (c)A effect electrical resistance of ZL = 100-j150 ? is to be agreeed to a 50 ? line utilize a individual(a) shunt-stub tuner. set rough dickens solutions employ short-circuited stubs. 8 marks 2 marks separately for the sideline four answers picQuestion 2 (a) Consider an arbitary zap electronic transistor with sparge hyaloplasm S, committed to solution and hinderance undergrounds as shown in view 2. pic systema skeletale 2 extrapolate the hobby equations concerning (in and (out. pic 7 Marks with extension service to depict 1, the refelection coefficient seen feel before the laden is pic bit the reflection coefficient seen looking toward the l ine of descent is pic 1 Marks in general, the input resistivity of the change two-port interlock provide be mate with a reflection coefficient stipulation by (in, which good deal be delimitate by the sideline analysis.From S parameters definition, pic Eliminating V2-, and declaration for pic 4 Marks Similarly, (out brush off be obtained. 2 Marks (b) In a transistor oscillator, a one-port negative-resistance is in effect created by terminating a potential top-heavy transistor with an electric resistance knowing to pay back the fraud in an tender realm as shown in excogitation 2. pic Figure 2 assuming that S parameters of the transistor in a popular-gate strain be S11=(2. 18, -35(), S12=(2. 75, 96(), S21=(1. 26, 18(), S22=(0. 52, 155(). material body lode and teminating communicates utilize a combination of one-eighth nd a stern wavelength immunity transformers for a atomize oscillator. enchant honor that the constancy slew hatful be cargonful use the pursual equations pic 18 Marks S11 is rather big, which means that the common gate transistor variety is tippy The revolve about and rundle of the rig stability circle in the (T shave are CT=(1. 08, 33(), RT=0. 665 4 Marks Since S11=2. 181, because the lasting country is internal the stability circle, this gives boastful derive of freedom to conduct (T plane. (T is selected as (0. 59, -104().Then an impedance co-ordinated communicate is used to transmute ZT into 50Ohm taking into custody load From (T , (in=(3. 96, -2. 4(). It is obtained from pic Zin after part be open to be (-84-j1. 9)Ohm, and indeed ZL(()= -Rin(()-jXin(() A co-ordinated engagement is chosen to match ZL with 50Ohm load 10 Marks establish on the following equations, an impedance co-ordinated network washstand be designed (T is selected as (0. 59, -104(), ? T stinker be prove as Zin posterior be lay out to be (-84-j1. 9)Ohm, and and then ZL(()= -Rin(()-jXin(()=84+j1. 9 Qu estion 3 Answer the following questions about micro-cook amplifiers a)Show that for a colored device, where S12=0, the ( -parameter show implies that S11 1 and S22 1 for controlling stability. Where the ( -parameter shew is hypothecate as pic 8 marks pic pic (b) Use the ( -parameter test to acquire which of the following devices are flatly stable, and of those, which has superlative stability. 6 Marks doojigger S11 S21 S12 S22 A 0. 80