Log-periodic antenna

In telecommunication, a log-periodic antenna (LP) is a broadband, multielement, unidirectional, narrow-beam antenna that has impedance and radiation characteristics that are regularly repetitive as a logarithmic function of the excitation frequency.

Note: The length and spacing of the elements of a log-periodic antenna increase logarithmically from one end to the other. Synonym log-periodic array.

Source: from Federal Standard 1037C and from MIL-STD-188