Log periodic antenna is a multi-element, directional, antenna designed to operate over a wide band of frequencies. The most common form of log-periodic antenna is the log-periodic dipole array or LPDA. 

The LPDA consists of a number of half-wave dipole driven elements of gradually increasing length, each consisting of a pair of metal rods. The dipoles are mounted close together in a line, connected in parallel to the feedline with alternating phase. Electrically, it simulates a series of two or three-element Yagi antennas connected together, each set tuned to a different frequency.