PANAMA VHF AND HF JUNGLE PROPAGATION.
Abstract
In hilly, mountainous, forested country, VHF communications are much better than expected. These tests show that it is reasonable to expect complete reliable coverage of an area 25 miles in diameter by using a balloon antenna 200 to 400 feet high at the command post with the patrol antenna raised on a 100-foot lightweight, blow-up mast. The steep, sharp, high, tropical hills are an advantage in most cases to VHF propagation. A better way to package the 6-ounce, lightweight cable such as is used for a 100-foot measuring tape is required. The PRC-25 is too heavy if it has to be carried 25 miles on jungle trails. A lightweight set similar to the PRC-35, but less the four-channel mechanism would be more useful if the 25 mile distance is actually a firm requirement. For HF, low power, less than 100 watts using vertical-incidence for the E layer reflection in the daytime is dependable. The use of shortened, quick-erectable, horizontal, antennas is feasible. Interference is the only reason that communications are difficult. The low frequency end of HF sets should start at 2 Mc/s or lower, not 3 Mc/s, and above 8 Mc is not useful for 25-mile circuits. The center-fed matching system is the most useful because it can be used for both short antennas and half-wave antennas with the least matching and tuning trouble. At night, from 2000 hours to 0600 hours in the morning, the frequency must be below 2.5 Mc/s and a half-wave, efficient antenna must be used. The GRC-9 is too heavy for foot patrols.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1963
- Accession Number
- AD0649066