Propagation
Propagation Analysis Software

Propagation Over "Line-of-Sight" Radio Paths

Author: R.J.Edwards G4FGQ © 5th September 2001

This program covers just the essentials. Refraction in the Earth's atmosphere, ground reflections and antenna radiating efficiency are not taken into account.

Antenna gains are relative to a hypothetical isotrope. Relative gain in the preferred direction of a 1/2-wave dipole is 2.1 dBi. A short dipole 1.8 dBi. Gain of an array of N dipoles = 10*Log(N)+2.1 dBi. Gain of a circular parabolic dish = 20*Log(N*Pi) dBi, N = diameter in wavelengths. A rectangular aperture of N*M wavelengths has gain = 10*Log(4*N*M) dBi. The gain of a short vertical above a perfect ground along the horizontal is 4.771 dBi. Note: Horizontal radiation of a ground-mounted vertical is groundwave. Over sea water and good ground the extra loss at MF is quite small and the program can be used to estimate ground path loss at distances up to the radio horizon of 50/Cuberoot(MHz) miles. As a crude approximation, estimate signal strengths via ionosphere reflections by adding 6dB to the line-of-sight data for each up-down hop.

Equivalent antenna apertures and beam-widths are included in the results. They allow better understanding of the performance of narrow-beam antennas at UHF. But beam-widths are meaningful only at antenna gains more than about 10 dBi.

Run this Program from the Web or Download and Run it from Your Computer
This program is self-contained and ready to use. It does not require installation. Click this link lineosite then click Open to run from the web or Save to save the program to your hard drive. If you save it to your hard drive, double-click the file name from Windows Explorer (Right-click Start then left-click Explore to start Windows Explorer) and it will run.


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