Introduction Frits, pa0fri describes the new generation of its
wire antenna. The article about new pa0fri wire centerfed antenna (yet
under construction in english) is here:
http://pa0fri.home.xs4all.nl/Ant/PA0FRI%20Antenna/pa0fri%20antenna%20eng.htm
The main idea was simple and good matching for coax fed of the antenna
in 80 meter band.
My experiences
The antenna gives good results on 3.576 MHz (tested on JT65 mode). The
important dimensions are:
1. Length of dipole L = 2 x 16.5 meter.
2. Configuration: INV V.
3. Height of instalation in feed point: H = 10 meter.
4. Length of ladder line 570 Ohm: LL = 12 meter.
5. Pass trough the wall is realised with two coaxials (2 x 0.5 meter), the
pass trough the wall reduces the required length of ladder line.
6. Was used only one serial capacitor from koax (coax type is RG 58,
length in my instalation is l = 2530 mm, C = ca 200 pF).
7. No baluns are required, tested for short coaxial H155 (3 meter) and
also for ca 20 meter long cable.
Schematics of antenna

Matching in Smith chart on 3.556 kHz

Conclusion The antenna gives good results and excellent matching
on one of frequencies of 80 meter band (for JT65 segment was VSWR below
1:1.2 after adjustment of coax capacitor). The antenna can be easily
matched with the automatic unbalanced tuner on all bands from 80 meter to
10 meter. |