  Determining the efficiency of an HF-antenna by measurements requires is a
complex procedure involving expensive equipment, calibrated instruments for
field strengths. In this paper we evaluate a simple, inexpensive method to
determine the relative efficiency of an antenna relative a reference antenna.
The method uses the Weak Signal Propagation Reporter(WSPR) network of receivers
that are located all over the world. These receivers report the estimated
signal-to-noise ratio of received beacon signals to the WSPR.net database where
the data can be retrieved (almost) in real time. In the paper we analyze the
method, estimate its accuracy and discuss advantages and limitations. Some
preliminary measurement results are presented.
