Max Blumer (WA1MKP) suggested that the developed antenna that occupies a minimum of space. The antenna is a loop with a perimeter equal to the wavelength.
The figure explains the intent of the designer of the antenna. As the basis was taken as the usual frame (left sketch) fed at points x and y. This frame radiates a vertically polarized wave in two perpendicular to the drawing plane directions, the maximum field strength is in the plane a-A'. The frame can be turned into a square, then (without significant loss of efficiency) in the rectangle (middle sketch). In this case the polarization of the wave and the orientation of the radiation will be the same as that of the round frame. If you fold this rectangle by 90°, first along the line a-A', and then line-In' and C - C', flat loop will turn into a three-dimensional cube (right sketch). The perimeter of the antenna, of course, will be equal to the wavelength (L), and each side of the cube will be only 1/10L.
It would remain vertical polarization of the emitted wave, and instead of a bi-directional polar pattern will be obtained almost Omni-directional diagram.
Set out the principle was first implemented as band antenna 144 MHz. To power used 50 Ohm coaxial cable with a matching unit (SWR over the range varied from 1.2 to 1.4). A study of the pattern by using the field strength meter showed that there is insignificant difference of the radiation back and forth (1.8 dB) and forward-sideways (3 dB), the latter apparently was due to the screening effect of the feeding cable and structural elements.
Then WA1MKP made a similar antenna on the 21 MHz band. It had the same characteristics (though the SWR was slightly higher). In addition to QSO with other States in the US have held communication with South America and Europe.
Author: Max Blumer; Publication: N. Bolshakov, rf.atnn.ru