Two vertically oriented half wave dipoles are spaced 1.5 wavelengths apart to from an array. Calculate the half power beam widths of the major lobes of the array, in the horizontal plane for the following two cases when the dipoles are fed with

(a) equal and in - phase currents (Broadside array)
(b) equal currents but with a phase difference of 540⁰ between the two currents (End fire array)

The electric field strength at a far-off point P due to a point charge + q, located at the origin O is 100 millivolts/metre. The point charge is now enclosed by a perfectly conducting hollow metal sphere with its centre at the origin O. The electric field strength at the point, P,

A 50 ohm lossless transmission line has a pure reactance of (j100) ohms as its load. The VSWR in the line is :

The skin - depth of copper at a frequency of $$3 GHz$$ is $$1$$ micron ($${{{10}^{ - 6}}}$$ metre). At $$12 GHz$$, for a non - magnetic conductor whose conductivity is $$1/9$$ times that of copper, the skin $$-$$ depth would be