On Fri, 26 Dec 2003 06:56:06 GMT, Dave J. wrote:

2 Meter / 440 question.

I have an RV with a fiberglass roof and a luggage rack on top of the
roof. I'd like to use the luggage rack as an antenna mount point since
there's really no other place to attach a mobile antenna if it needs a
ground plane.

But I doubt if the rack is grounded to the vehicle frame. Should I
bother running some ground braid down to the frame or will the coaxes
shield itself provide enough ground to allow normal antenna
performance.

Thanks.

Dave

Hi Dave,

Depends....

Upon the size of this luggage rack. How big is it in terms of
wavelength? More than a quarter wave for 2M (probably) and it
qualifies as enough metal to do the job. You may also be able to
gamma match to the luggage rack itself and make it an Halo antenna
(provided it has a full circle of continuity); but in that regard, it
is probably too big (perhaps 6M then?).

In real estate they have the three determiners of success: location,
location, location. For us, that is not to far off, but rather:
location, size, wavelength (or Meters³, Meters², Meters¹).

73's
Richard Clark, KB7QHC