Saturday 31 January 2009

G5RV – flat or inverted V?

I did some tests recently with a G5RV in inverted V configuration. I was very disappointed. Don’t get me wrong, I know that the G5RV is a compromise antenna, but I found that some DX signals were inaudible compared with my 20m dipoles in the loft. Why?

Turns out that if you use a long multiband antenna as an inverted V it really changes the radiation pattern. The lobes contract quite badly and the radiation angle goes up dramatically. I lost about 7db east-west and the low-angle DX capability went through the floor.

An inverted V half-wave dipole doesn’t do this, so if you must have an inverted V for 20m, use a half-wave dipole, not a G5RV or OCF (Windom).

Save your inverted V G5RV or Windom for 80m where they seem to work quite well with high-angle radiation.

Above right: The red trace is a G5RV inverted V with the apex at 12m and the ends at three metres. The blue trace is a flat-top G5RV at 12m. These were produced with MMANA-GAL, an excellent program.

1 comment:

  1. Well, there is ''it won't work'' and ''it bloody does'' scenarios, I mean technically you may be right, but life brings exceptions and surprices. I have G5RV in V confing, and it is for my circumstances the best antenna I can have, if you want a proof look up 2E0FHM, 73's !