effect of dipole infront of cylinder

Hello
iwant to know what will the effect of dipole infront of perfect electric conductor cylinder in terms of gain by varying the distance between dipole and cylinder. Please let me know if any refernce material r books available..

If the cylinder is in the Reactive Near-Field of the antenna, it will distort the dipole radiation pattern.
Reactive Near-Field is the region close to the antenna where the Electric-E and Magnetic-H fields are not orthogonal and anything within this region which couple with the antenna will distort the radiated pattern.
Also an external λ/2 coupled conductor near a dipole placed to a certain distance (approximately λ/10) become a reflector changing the antenna gain to opposite direction.