Jay wrote:

No, it just tells you how good the impedance match is. A good match
is a necessary, but not sufficient condition, to a high efficiency
antenna installation. However, a power meter in the far field will
tell you how good your antenna is and give you a relative indication
of how adjustments are effecting your ability to reach out and touch
someone.

(JFLEISC) wrote in message
Will one of those SWR meters tell you anything?

Very true, and the efficiency may depend on the surface used as a
ground plane as much as anything else.

Peter

P.S.: It is also usefull to check more than one frequency!