The dipole antenna (see next two photos) spans this abandoned railroad
cut in the wide open space of eastern Washington State, location of several
attempts to direct PBase signals to specific areas. The profile of the
cut acts as a signal amplifier, much in the same manner as the huge
radio telescope at Aricebo, Puerto Rico (see link below) or
the mirror of a reflecting telescope.

Here's a picture and info about the radio telescope mentioned above:
( http://www.naic.edu/public/the_telescope.htm )
.