Abstract: The invention provides a helical antenna to broadcast a signal from an input line. The antenna includes a base plate and a dielectric rod mounted on the base plate. A conductive helix, surrounds the dielectric rod, and the rod has a pitch angle of at least 12 degrees. A matching network is connected to the conductive helix, to match an impedance of the conductive helix with an impedance of the signal.

Abstract: A parallel fed colinear dipole array antenna for broadcasting and receiving a signal of a selected wavelength. The antenna comprises a plurality of elongate dipole antennas attached end-to-end in a linear array. A power divider divides and transmits a signal in parallel to each of the dipole antennas. The linear spacing of the dipoles is correlated with the dimensions of the dipoles and the selected wavelength, such that the signals of the dipole antennas interfere with each other when broadcast, so as to focus signals which propagate substantially perpendicularly to the linear array, and to diminish other signals.