Antennas made of wire are the oldest type of antenna system. They are generally easy to construct, but, particularly on frequencies below VHF (below 30 MHz), their required length can be inconvenient or not practical for the space available for their construction and use.
A common wire antenna used on frequencies below 30 MHz is called a “dipole”, in which equal lengths of wire (typically copper wire) are typically fed by a two-conductor RF transmission line or feed line (such as coaxial cable, ladder line, or twin lead) at a wire junction. The combined length of the two antenna wire components is traditionally determined by the formula:l=468/f 
Where “f” is the desired resonance frequency in megahertz and the resultant length “1” is in feet. For example, for an antenna to be resonant on 3.755 MHz, a frequency in a popular amateur “ham” radio band, the overall length of the wire needed is approximately 124.6 feet (468 divided by 3.755). In a classic dipole configuration, this length of wire is divided in two (62.3 feet for each wire radiator) and fed by a two-conductor transmission line. To suspend the wire elements, the end points of the wire segments are attached to non-electrically conductive elements (insulators), usually made of ceramic or plastic. The insulators are fastened to lengths of non-electrically conductive support line, such as rope. The rope ends are typically fed through pulleys attached to support structures; tension is applied to the overall rope-and-wire system to create a horizontal antenna system.
One unavoidable problem with this type of antenna is that tension is created throughout the entire system, including the wire elements. Over time, it is common for the wire to stretch and break—and thus requiring the wire element(s) to be repaired or replaced.
Another problem with a common dipole antenna is the overall length required. In the above example, a radio operator may not have the 124.6 feet necessary on his or her property to suspend the dipole. Apartment dwellers and homeowners with small properties may be particularly challenged to find the 124.6 feet of horizontal space without impinging on neighbors' properties.
As inadequate horizontal space is such a common problem, a number of options have been developed to modify a dipole to function at a shorter-than-natural resonant length.
One shorter-length option is to include what is commonly referred to as “loads” in the lengths of wire; these loads are typically comprised of coils that electrically simulate a longer length of wire. However, the efficiency and performance of“loaded dipoles” is significantly less than full-length dipoles.
Another shorter-length option is something called a “Slinky®-antenna”—whereby the wire of the antenna is made of a child's Slinky® toy, which is essentially coiled spring-metal. There are numerous problems and deficiencies with the coiled spring-metal antenna. One such deficiency is that the coils are not ordinarily created by the end-user; the coiling process of the spring steel is beyond the means of most people. Another deficiency is that a coiled spring-metal antenna can only be stretched out to approximately 15 feet without permanently deforming the coil. Other common reported deficiencies include that the resonance, impedance, and standing-wave ratio (SWR) characteristics of the coiled spring-metal antenna tend to change when wet. Another deficiency of the coiled spring-metal antenna is inherent in the coil itself, as the antenna radiators are essentially large helical inductors which provide unusual and inefficient RF transmission and reception characteristics. All in all, due to these and other deficiencies, the coiled spring-metal antenna has never gained wide acceptance in the RF-transmission community.
Beyond the common dipole antenna, there are other popular wire-antenna types that suffer similar disadvantages, whereby persons do not have the physical space on their properties to readily install them. This is particularly noted on lower operating frequencies where the associated radio wavelengths (and thus resonant antenna wires and/or elements) are long. These disadvantaged wire-antenna types include end-feds, slopers, doublets, inverted vees, G5RVs, OCFs, long wires, and wire beams.
Moreover, even when a person has the physical, horizontal space to install a full-size antenna, there are instances where height is the limiting factor. For instance, in some communities there are zoning restrictions related to structure heights. In other instances, there are personal and/or aesthetic inhibitions to erect antenna structures that can be upwards of 60-70 feet tall.
Given the above-described issues with shortened antennas, and the practical limitations and restrictions of full-size antennas, one skilled in the art would understand the benefits of antennas and antenna components that provide the function of physically larger, full-size antennas and antenna components without employing coils that compromise performance.
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