The Delta for 80 and 40 meters was designed
for installation on the roof of a building with help of a metal
mast. Design of the antenna is shown on Figure
1. Link for file *maa for the antenna is given below
at the article.
File *maa contains correct dimension for the
antenna. However, MMANA simulates the antenna in not correct way.
Correct data may be reached using NEC for MMANA. All of these
programs are free. Figure 2 shows patterns (in horizon and vertical
plane) of the antenna on the 80 meters. Figure
3 shows patterns (in horizon and vertical plane) of
the antenna on the 40 meters.
Matching of the antenna at both bands is possible
with the help of the length of 75-Ohm Coaxial in 4.82-meters.
SWR at the both bands (at this case) is 1.46:1.0. Figure
4 shows diagrams and data
for the matching. Improved
variant of the matching is shown on the Figure
5. A length of 75-Ohm coaxial cable in 3.9 meters and
opened stub from a length of 75-Ohm coaxial cable in 1.7 meters
are connected to antenna’s terminal. SWR at the both bands (at
this case) is 1.23:1.0.
It is a theoretical model. In the coming spring I hope to install and
check the antenna.