Category - Traveling Wave

The Quadrifilar Helix (QFH) antenna, with its unique design and circular polarization, ensures efficient NOAA satellite signal reception. This article explores the history, key characteristics, and practical modeling of QFH antennas using AN-SOF, providing valuable insights for RF engineers and enthusiasts.

Inverted V antenna over real ground. The operating frequency is 7.2 MHz which corresponds to a wavelength of almost 40 meters.

The horizontal arms of the V-antenna are 3 wavelengths long, so six semi-cycles of a sine function can be seen as a current distribution along the arms.

Frequency sweep simulation of a directional helix antenna backed by a ground plane of finite size. The ground plane is modeled using a circular grid of thin wires.

Directional helix antenna backed by a perfect ground plane. A directional radiation pattern is obtained pointing towards the helix axis.

Simulation of a Yagi antenna that consists of seven linear wires. A directional radiation pattern is obtained as can be expected.

Simulation of a Yagi antenna that consists of five linear wires. The driven element is a folded dipole which does not change the radiation pattern shape, but it changes the input impedance for an easier impedance matching.

Simulation of a Yagi antenna that consists of three linear wires. A directional radiation pattern is obtained as can be expected.