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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.
The antenna radiation pattern strongly depends on the length and height. In the examples below I hope to make the differences clear.
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 ...
5 cze 2021 · The Antenna Calculator for Half-Wave Dipoles. Enter your desired frequency (MHz) of operation (i.e. 3.55). If you have no particular preference within a given ham radio band, then simply enter its center frequency (i.e. 7.15 for the 40 meter band).
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.
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.
NOTE 1 – Part 1 to Annex 1 gives comprehensive and detailed information on the theoretical characteristics of HF transmitting antennas. Computer programs have been developed from the theory to calculate the radiation patterns and gain for the various included antenna types.
