A thin plate dipole and a cavity backed dipole antenna are designed and fabricated. Their input impedance as function of frequency and radiation pattern are measured. It is experimentally verified that input impedance and radiation pattern of the thin plate dipole are equivalent to those of the circular cylindrical dipole if the radius of the circular cylindrical dipole a = w/4, where w is the width of the thin plate dipole, provided a and w are much smaller than the wavelength. For both E and H plane pattern, the half power beam width of the cavity backed dipole antenna is measured as 80˚. For monopulse tracking system,4 thin plate dipoles are positioned above a conducting plate and difference pattern is measured to give-40dB dip at the center frequency 1.625 GHz.
