Vellore Institute of Technology 2008 B.Tech Electronics and Communications Engineering term end - Question Paper

1. Derive an formula for the voltage and current in a line having a length of L and also at the sending end and receiving end voltage and current. (15)
2. Express the different components, if the parallel plates which having infinte length in Y & Z direction that are kept in a non-conducting region. (15)
3. A standard air filled rectangular wave guide with dimensions a=8.5cm, & b=4.3cm is fed by a 4GHz carrier from co-axial cable. Determine if a TE11 mode will be propagated. If so compute Vp & Vg. (10)
4. A transmission line has a characteristic impedance of 200? terminated bya load of 400+j200?. obtain (a) SWR, (b) K, (c) Zin at S=0.7? from the load, (d) input admittance at a distance of 0.7? from the load, (e) position of Vmax and Vmin. (10)
5. find the normalized load impedance with (a) K=0.5?0? (b) K=0.5?60 (c) K=-1, (d) K=0.3?-30, (e) K=j (10)
6. Find the primary and secondary constants of the line 50km long when ZOC measured by a bridge at 700Hz is 286?-40? ? and ZSC = 1520?16?. (15)
7. For a frequency of 6000MHz and phase separation of 7cm, obtain the subsequent for TE10 mode. (i) critical frequency,(ii)ß,(iii)a & ß for f=0.8fc, (iv) a & ß for f=1.25fc, (v) ?c. (10)
8. A gold parallel strip line has subsequent parameters relative dielectric constant of Teflon erd = 2.1, strip width w = 26mm, separation distance d= 5mm, conductivity of gold sc= 4.7*107 mho/m, frequency f= 10GHz. Determine (a) surface resistance of the gold strip, (b) Characteristics impedance of the strip line, (c) phase velocity. (10)
9. A certain microstrip line has the subsequent parameters er = 5.23, h = 7mils, t=2.8mils, and w=10mils. compute the characteristics impedance of the line (5)

Earning:   Approval pending.