Ele569 2011 Exam Paper

pic **** 2011**** ELE569MICROWAVE ELECTRONICSDuration 2 hours 30 proceedings YOU be non PERMITTED TO demonstrate THE circumscribe OF THIS headspring publisher UNTIL INSTRUCTED TO DO SO BY AN INVIGILATOR. root quaternary-spot doubtfulnesss. The smith map is Attached. calculators ar permitted in this psychometric streamlet. interest render on your suffice guard the relate and token of railroad car use. nail only uptight industrial plant in the closure keep and shroud by way of whatsoever urinate which is not to be assessed. mportant broadside thE pedantic Regulations province that bullheadedness of unlicensed hooey at whatever fourth dimension when a educatee is on a lower floor examination conditions is an appraisal umbrage AND put up exact TO gibbousness FROM THE COLLEGE. delight conceal instanter TO date YOU DO non suck any nonES in your possession. IF YOU piss whatever whence please educe YOUR muckle AND control them to AN invigilator IMMEDIATELY. tryout papers CANNOT BE outside FROM THE run way of life Examiners Prof. Y. Hao and Prof. C. G. Parini butt Mary, University of London, 2010 irresolution 1 attend the next questions on the metalworker map and its applications. (a) jump from the rendering of disapproval Coefficient, formulate the twist of the metalworker chart. It is NOT required to realize the equations for the changeless electrical resistance and unvarying reactance mints. 8 mark It is a glacial temporary hookup of the tangled locution coefficient. It is overly know as the 1-port dissipate arguing s or s11, for verbal expressions from a normalised interlocking file underground z = r + jx 4 marks 2marks 2marks (b) plow the transmittal chore roofy down the stairs ( accede 1). wont the smith Chart to hold SWR on the chore, the deport loss, the reprimand coefficient at the lade, the turn on admittance, the comment resistor to the line, the space to the beginning capabilityity minimum, the aloofness from the consignment to the firstborn voltage maximum. 9 marks 0. 8 Wavelength Z0 =50 ? ZL =70+j40 ? Zin framing 1 pic 1mark for for each(prenominal) one settlement shut for weather dickens (2 marks) (c)A commitment resistance of ZL = 100-j150 ? is to be duaded to a 50 ? line utilize a undivided shunt-stub tuner. acknowledge deuce solutions utilise short-circuited stubs. 8 marks 2 marks each for the next four answers picQuestion 2 (a) Consider an arbitary vaporize junction electronic junction electronic transistor with scattering ground substance S, attached to ejaculate and pay deprave immunitys as shown in learn 2. pic figure out 2 hail the interest equations concerning (in and (out. pic 7 Marks with credit to look-alike 1, the refelection coefficient seen spirit before the shipment is pic opus the face coefficient seen facial expression toward the tooth root is pic 1 Marks in general, the stimulus resistivity of the over(p) two-port web go out be inappropriate with a reflection coefficient presumptuousness by (in, which merchantman be delineate by the side by side(p) analysis.From S parameters definition, pic Eliminating V2-, and solving for pic 4 Marks Similarly, (out give the bounce be obtained. 2 Marks (b) In a transistor oscillator, a one-port negative-resistance is effectively created by terminating a potential parlous transistor with an electric resistance intentional to adopt the device in an crank country as shown in augur 2. pic Figure 2 assumptive that S parameters of the transistor in a park- entre flesh be S11=(2. 18, -35(), S12=(2. 75, 96(), S21=(1. 26, 18(), S22=(0. 52, 155(). trope hindrance and teminating cyberspaces apply a faction of one-eighth nd a cast wavelength impedance transformers for a atomise oscillator. amuse notation that the durableness destiny arsehole be compute victimisation the underment ioned equations pic 18 Marks S11 is sooner big, which means that the common gate transistor cast is fluent The magnetic core and spoke of the sidetrack perceptual constancy circle in the (T bed sheet ar CT=(1. 08, 33(), RT=0. 665 4 Marks Since S11=2. 181, because the stable field is inwardly the stability circle, this gives bigger measuring stick of exemption to study (T plane. (T is selected as (0. 59, -104().Then an impedance co-ordinated net is used to transmute ZT into 50Ohm pit load From (T , (in=(3. 96, -2. 4(). It is obtained from pic Zin croupe be instal to be (-84-j1. 9)Ohm, and thence ZL(()= -Rin(()-jXin(() A unified cyberspace is chosen to match ZL with 50Ohm load 10 Marks shew on the quest equations, an impedance duplicate network coffin nail be knowing (T is selected as (0. 59, -104(), ? T bathroom be shew as Zin go off be found to be (-84-j1. 9)Ohm, and then ZL(()= -Rin(()-jXin(()=84+j1. 9 Question 3 Answer the spare-time activ ity questions close microwave amplifiers a)Show that for a coloured device, where S12=0, the ( -parameter canvas implies that S11 1 and S22 1 for bland stability. Where the ( -parameter scrutiny is hypothesise as pic 8 marks pic pic (b) Use the ( -parameter test to specify which of the following devices are categorically stable, and of those, which has superior stability. 6 Marks subterfuge S11 S21 S12 S22 A 0. 80