Length L of the antenna (see Figure 1a) depends to dimensions
of a car, where the antenna is installed, usually the length close
to 6 meters. The antenna feeds with help a short length of a two-wire
line, usually the length is equal to 2- 3 meters, an
ATU is used. Antenna is adjusted with help of a symmetrical variometer
LT installed at opposite ends of the tuned dipole. The antenna
is tuned on maxima of RF current to points A. In such case the
antenna ensures maximum effective work. But in the manual of the
antenna is pointed, that the antenna in some cases can be tuned
on maxima of RF voltage on points A. Such set-up for the antenna
is possible if the communication car is placed on a good conducting surface
(it can be moist salty soil) or by operation from natural shelters
- holes, ravine. Inductances of antenna variometer vary from several
microhenry up to 300 microhenrie. The antenna works good at 2-25 MHz.
At usage of this
antenna in military communication car, the antenna gives that
advantage, that the roof of the automobile remains free. It enables
to install on the roof other antennas,
for example, for VHF- UHF ranges
was in use within the World War II and till 70s of the 20 century.
The dipole is a wire folded by meander and loaded to serial coil
plus a capacitor. Figure 2
shows the disposition of the folded dipole on communication car.
The antenna is located at the altitude approximately at 1-1,5
meters above the roof. Figure 3 shows the scheme of the
antenna. Wings of the folded dipole
could reach to 10-15 meters in length. It depends on sizes
of the car.
is fed by two-wire ladder line in length about 3 meters. The line
is connected to an ATU. The antenna is tuned on maxima of RF current
to points A. Folded dipole is tuned in resonance in the operation
frequencies with help of loading spools LT together with capacitor
C, that made as a constructing part
of the car.
antenna is intended for 60-90 meters, and usually does not work
at other ranges. . Folded dipole has strongly radiation to the
sky and a little to the horizon.
with low characteristic impedance
low characteristic impedance is intended for a work at wide frequencies
range and for installation on the roof of a communication car
that has small dimensions. Figure
4 shows the scheme (Figure
4A) and disposition (Figure 4B) of the dipole on communication
car. I must say, that I have seen some photos, where the antenna
was installed athwart to the roof, as it is shown at Figure 4C. The antenna is located at the altitude
approximately at 1 meter above the roof. Wings of the dipole made as a metal
grid has shape, crosswire at the cells soldered. The wing of the
dipole has the width in (0,5-1,5)-meters and the length (1,5-2)-meters.
Figure 5 shows the scheme of feeding of dipole with low characteristic impedance.
The antenna is connected through a two-wire ladder line in about
2 meters length to an ATU. The ATU has a resonance