Effects of a high-impedance screen on a dipole antenna

A high-impedance conductor with reflection coefficient magnitude near unity and appropriate phase would allow a parallel dipole to be closely spaced to the screen. Phase is critical; this paper examines the pattern, gain, and impedance properties of a dipole antenna located close to a high-impedance material. The material is idealized with a unity reflection coefficient and a variable phase angle from -/spl pi/ to +/spl pi/. An example uses a half-wave dipole-spaced wavelength from the material. For a phase angle around 135/spl deg/ the pattern is unstable and has a null at broadside. Gain varies from 10 to 0 dB. Input impedance varies widely with phase angle, presenting a mismatch loss situation. From these data an acceptable range of phase angle verses frequency can be inferred.