Hobbies And Interests
Long Wire Antennas
The simplest of the best homemade antennas is the long wire antenna. As its name suggests, it's simply a long piece of wire. Sometimes random length, but usually cut to about a 1/2 wavelength, a 60-foot long wire antenna radiates well between 7.0 and 28.5 MHz. A trans-match antenna tuner is usually required with this type of inductor to tune for the lowest SWR, or standing wave ratio.
Dipole Antennas
The dipole antenna is an efficient radiator of electromagnetic waves and is the antenna design against which all other antenna designs and performances are compared. Near-resonant SWR may be achieved by cutting this two-part wire antenna to the following formula: length (feet) = 468/frequency. For example, a dipole for 14.2 MHz needs to be about 33 feet long. Use of balanced transmission lines increases the efficiency of all balanced antenna systems such as dipoles.
G5RV Antennas
Invented by Louis Varney, this 102-foot-long dipole-type antenna is functional on a variety of radio frequency wavelength bands. Ease of design, fast and easy construction, portability and broadbandedness --- the wide range of frequencies covered --- make the G5RV one of the best homemade antennas and one of the most popular. Feeding this antenna through a trans-match antenna tuner and a balanced transmission line maximizes its radiated output.
Carolina Windom Antennas
The Carolina Windom antenna is a highly efficient and effective unbalanced radiator with 83 feet of wire on one side and 50 feet on the other. Its design calls for a simple balun, 4:1 transformer, coaxial transmission line that's not balanced, and a trans-match antenna tuner. The balun converts the balanced signal to an unbalanced one for using coaxial cable. The Windom's low angle of elevation, omnidirectionality and broadbandedness make it a favorite of long-distance communications operators.
Vertical Antennas
An easy-to-build, portable and low-footprint vertical ground-plane monopole antenna may be fashioned from a single piece of wire and a few optional ground radials. A 1/4 wavelength vertical antenna cut to the formula height (feet) = 234/frequency is more broadbanded in the higher-frequency bands and needs to be cut with greater precision among the lower frequencies. A vertical antenna for 3.8 MHz needs to be 61.6 feet high. A trans-match antenna tuner helps match the antenna, but a resonant antenna is always a more efficient radiator.
Sky Wire Loop Antenna
Fashioned from 574 feet of wire arranged in a giant loop or square in the sky, the sky wire loop antenna is a sensitive receiver and efficient radiator of radio waves. Efficiency increases with balance and configuration with a directional pattern developing opposite from the feed-point. A balanced ladder line and a trans-match antenna tuner, as well as inherent resonant sweet spots in this antenna, make it broadbanded throughout the high-frequency spectrum. Short feed-lines are required at higher frequencies.
Directional Beam Antennas
Efficiency and effectiveness of wave radiation is improved by focusing RF energy in a specific direction. Although bending a simple dipole has some directional utility, adding director and reflector elements to the driven dipole element can produce a selective directional antenna. This is the essence of the yagi beam, which looks like a rooftop TV antenna whose multiple elements focus the signal in a given direction. A similar arrangement of looplike antenna elements is the essence of the cubicle quad directional beam. All of these beams can be home-built using wire and structural elements such as PVC pipe or bamboo spreaders to hold the wires in place.