PURPOSE: To obtain a monopulse tracking antenna with a simple constitution, which can obtain a Σ output and a Δ output of a directional pattern without using a hybrid circuit.

CONSTITUTION: On a printed board 1 of the same plane, three piece of first to third antenna elements P1-P3 are arrayed, and to each antenna element, feed by a feeder constituted of micro-strips M1, M2 is executed. A micro-strip M1a provided between a first and a second antenna elements P1, P2 is set to length for generating a phase difference π between both of them, and by synthesizing characteristics of these antenna elements, a Δ output can be obtained. In a third antenna element P3, a Σ output can be obtained by executing inpendently feed.