Abstract-In recent years, monopole antennas have become one of the vital components of cellular mobile communications and internet networks across the globe. Their relatively easy and low fabrication cost and faster installation makes them an obvious choice for developing countries. The most common form is the quarter-wave monopole, in which the antenna is approximately 1/4 of a wavelength of the radio waves. In this paper, we present the analytical treatment of a quarter-wave monopole antenna above virtual ground. Virtual ground is realized by using bent radials around the vertical monopole element. Radiation resistance and gain of the quarter-wave monopole are mathematically derived and three-dimensional radiation patterns are simulated using sinusoidal current distribution. It is observed that for the case of the quarter-wave monopole, we achieve twice the gain of a dipole antenna of half-wave-length long. As the radiated power is limited to upper hemisphere of the ground plane, the total radiated power of the quarter-wave monopole is half of that of a dipole. Hence, the value of radiation resistance of the monopole is half of that of a dipole.Index Terms-Ground plane, radiation pattern, directivity, half-wave dipole, monopole antenna.

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