Search results
1 wrz 2021 · World map of ground conductivity and permittivity for calculating antenna ground losses and radiation patterns.
20 kwi 2003 · Following is a series of dipole radiation pattern plots, produced by a popular antenna modeling program. The first plot below shows a dipole at an elevation of two wavelengths above a standard earth ground model. Note the multiple lobes at varying elevation angles above the horizontal.
Antenna radiation pattern depending on length and height. In the images below, I hope to clarify how length and antenna height affect the antenna radiation pattern. In many cases, the available space around the house determines the size and height of the antenna.
OW ELEVATION ANGLE(a in Fig, 6). Therefore, to judge antenna performance, it is more useful to have an antenna pattern showing the radiation at 30. egrees or more above the horizon. Figure 8 is a diagram showing the signal strength (represented by vectors) radiated from a typical half-wave dipole anten.
Optimize antenna radiation pattern for the desired takeoff angle. Optimum NVIS height for horizontal dipoles: 0.18–0.22λ for TX and 0.16λ for RX. courtesy of Chris, N6CTA. The NVIS map shows the recent global distribution of critical frequency (foF2) .
Computer programs have been developed to calculate the radiation patterns and gain for the following types of antennas, as used by administrations, for HF broadcasting and other services: arrays of half-wave horizontal dipoles; quadrant antennas and horizontal dipoles; log-periodic antennas; tropical antennas; rhombic antennas and vertical ...
In HF broadcasting the antenna is the means by which the radio-frequency energy is directed towards the required service area. The selection of the right type of antenna will enhance the signal in this area, while reducing radiation in unwanted directions.
