MFJ-1778 G5RV Multiband Antenna
2
30 meter band:
On 30 meters the MFJ-1778 (G5RV) functions as an extended
double zepp. The current distribution of the antenna and
matching line is shown in figure 3. The horizontal radiation
pattern is similar to the pattern of the 40 meter band (broadside)
but has four additional minor lobes. The antenna has a gain of
around 3 dB on 30 meters.
20 meter band:
This is the true design frequency of the MFJ-1778. The
antenna is a 3/2 wave center-fed antenna and has a multi-lobe
pattern on this band. On this band the G5RV is a good DX
antenna at heights of 30-60 feet. The radiation angle is fairly
low. The feedpoint of the antenna is approximately 100 ohms
resistive, and the ladder line functions as a 1:1 ratio
transformer. See figure 4 for a digram of current distribution.
17 meter band:
The antenna is a pair of full-wave antennas fed in-phase on this
band. The radiation angle of the antenna is low with many
lobes in all directions. The current distribution of the antenna
and matching line is shown in figure 5.
15 meter band:
The antenna is a pair of 1.1 wavelength long wires fed in-phase on
this band. This pattern is multi-lobed in the horizontal plane with
a low radiation angle. The current distribution of the antenna and
matching line is shown in figure 6.
12 meter band:
On 12 meters this antenna is a pair of 1.3 wavelength longwires
fed in-phase. The feedpoint resistance is fairly low. The
radiation pattern has many lobes and a low radiation angle. The
current distribution of the antenna and ladder line is shown in
figure 7.
10 meter band:
The MFJ-1778 functions as two 3/2 wave longwire antennas fed
in-phase on this band. The pattern has multiple lobes in all
directions. The current distribution of the antenna and matching
line is shown in figure 8.
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
