In this paper, the behavior of radiation and coupling reduction between trio groove-backed antennas is investigated. An electric line current is placed inside a rectangular groove in a perfectly conducting plane. Fourier transform and series techniques are employed to express the scattered field. Boundary v conditions are enforced to obtain simultaneous equations for the discrete modal coefficients, which are then solved in order to calculate the radiated and coupled fields. The behavior of coupling reduction and radiation is discussed in terms of the antenna geometries, (C) 2003 Wiley Periodicals, Inc.