Delta from 10 to 40 meters
During the conversation on the air with Mike (G4HOL) I learned about his compromise antenna. His "story" was able to record almost word for word. But, above all, for a better understanding will lead figure, illustrate this. Comment G4HOL: the Perimeter of the antenna, as seen in figure 43,13 meters. The location above the earth's surface horizontal. In the range of 40 m works at a large angle to the horizon. With increasing frequency, the angle of radiation is reduced and the gain increases. The antenna is non-resonant.
Work starts after correct adjustment of the control elements of the antenna the tuner. It fails to get the SWR is equal to 1, almost all bands. When the input power is 300 - 400 W TVI not found. Recommended as an antenna for operation in the field. Comment EW1MM: FROM the point of view of the theory, contraindications to the use of this antenna is not. However, based on the formula for determining the perimeter of such antennas L = 306,3 / F (MHz) its perimeter should slightly increase to 43,44 m (for frequency 7.050 MHz). On other bands will all be "stacked" using a balanced tuner.
It is very important to use precisely, the symmetric tuner without the use of transformers, for example, the USS block p/St P-140 or Key to see the book and Lipinskogo "Antenna SW/УSW waves", p. 152. In stationary conditions, from the point of view of losses, it is better to apply a homemade wire feeder 450 ... 600 Ohms. For operation in the range of 10 to 80 m of the perimeter of the antenna should be calculated based on the range of 80 meters. The antenna if the conditions can be positioned and vertically. If you cannot get the SWR is close to unity, because of imperfections in the antenna tuner, it is necessary to slightly change the length of a balanced feeder.
Comment RW3AY: 's interest that the antenna is very large, and I think you should explain to the professionals. I think Vladimir (EW8AU) will not refuse to make a comment, and I, in turn, will further inform our readers.
Author: I. Podgorny. EW1MM, Minsk; Publication: N. Bolshakov, rf.atnn.ru