VAN GORDON
G5RV ANTENNA
3.5 thru 30 MHz
INTRODUCTION
The G5RV is an excellent all-band antenna (3.5 – 30 MHz) 102ft. dipole.
The 102ft. dipole with 31ft. feeder of 450 ohm transmission line achieves a
resonance on all bands from 80 to 10 meters with only one antenna without any
loss in traps and coils. The impedance at the end of the 450 ohm feed line is
approximately 50 – 60 ohms.
DESCRIPTION OF
OPERATION
On 3.5 MHz, the electrical center of the antenna
starts at approximately 15ft. down the 450 ohm line. On 3.5 MHz a portion of
the dipole is operating as a folded dipole. The antenna functions as two
half-waves in phase on 7 MHz with a portion folded in the center. In the 14 MHz
band, the antenna operates as a three half-wavelength antenna. On 21 MHz the antenna
is two full-wavwlengths in phase. In the 28 MHz band it operates as two one and
a halfwave in line fed in phase.
The G5RV is slightly short on 80 meters where the 450
ohm line serves as a form of matching stub and both a stub and/or impedance
matching transformer on the other bands.
INSTALLATION
The G5RV must be fed with a coaxcable at least 70 FT.
long in order for the antenna to perform properly. The height for maximum
efficiency of the G5RV is at one full wavelength above the ground on the lowest
frequency for which the antenna is to be used. It is impossible to achieve this
height in most antenna installations. Erect the G5RV as high above the ground
as possible with the 450 ohm feedline dropping down vertically toward ground,
before bringing it away at an angle or parallel to ground. This will minimize
coupling of line with the antenna. The performance of the antenna is modified
considerably with each installation due to changes in ground and surrounding
environment. The antenna will so perform satisfactorally when installed as a
inverted vee type antenna.
The antenna comes completely assembled and is ready
for installation at your location. Before unwinding the antenna elements,
decide where you are going to suspend the antenna. Overall length is 102FT. so
at least 110FT. should be available when being installed in a dipole
configuration. Less space is required to erect the antenna as an inverted vee
type antenna will vary depending circumstance at your location.