In the radiation pattern of a 3-element array of isotropic radiators equally spaced at distances of $${\lambda /4}$$ it is required to place a null at an angle of 33.56 degrees off the end-fire direction. Calculate the progressive phase shifts to be applied to the elements. Also calculate the angle at which the main beam is placed for this phase distribution.

Referring to the figure. The switch S is in position 1 initially and steady state conditions exist from time t = 0 to t = t₀. At t = t₀, the switch is suddenly thrown into position 2. The current I through the 10K resistor as a function of time t, from t = 0 is (in mA) _____________.

(Give the sketch showing the magnitudes of the current at t = 0, t = t₀ and t = $$\infty$$ )

The small signal capacitances of an abrupt P⁺−N junction is 1 nF at zero bias. If the built-in voltage is 1 volt, the capacitance at a reverse bias voltage of 99 volts is equal to

A silicon sample is uniformly doped with 10¹⁶ phosphorous atoms/cm³ and 2 ×10¹⁶ boron atoms/cm³. If all the dopants are fully ionized, the material is