Consider a knife edge mountain which is located between a radio station and a listener holding a portable radio at a height $2$m$.$ The radio station operates at a frequency of $100$MHz$,$ and is positioned at a height of $90$m$.$ The distance between the radio station and the listener is $800$m$.$ Consider the total height the mountain to be $100$m$.$ The ground distance between receiver and the mountain is $200$m more than the

distance between the radio station and the mountain. $[3+2+3+2=10$ Marks$]$

$($a$)$ Calculate the height of the obstacle which is blocking the direct view of the receiver from transmitter

$($b$)$ Calculate the diffraction parameter.

$($c$)$ Find the diffraction gain due to the presence of knife edge.

$($d$)$ Identify the Fresnel zone within which the tip of the obstruction lies.