The paper describes a new design method for a wideband array of log-periodically scaled microstrip resonator antennas. The radiating elements are series-fed by a simple coplanar microstrip network. This network consists of an open-circuited feed line with a branch line connected to each radiating element. Both a network and a radiating model for the complete structure are explained. These models predict with good accuracy the input impedance and the radiation pattern as a function of frequency. The results for a 5-element 5-band antenna are presented as an illustrative example. This antenna combines a good impedance match (VSWR < 2.6) with a reasonable power gain in broadside direction (> 5.5 dB) over a 22% bandwidth. This means a tenfold increase in the bandwidth in comparison with a single microstrip resonator antenna. List of principal symbols BW C E,H >nK bandwidth capacitance of resonator electric, magnetic field dielectric constant of substrate absolute permittivity, permeability of free space frequency frequency, angular frequency, free space wavelength at resonance correction factor for surface roughness substrate thickness L, W Q.Q md D D O D P Pcu s t tan 5 x, y, z Z X / 4z m = resonator length, width = expansion factor of log-periodic structure = quality factor, radiation quality factor of resonator md = resonant, copper loss, dielectric loss, radiation resistance of resonator = reflection coefficient magnitude = copper resistivity = specified voltage standing wave ratio (VSWR) = copper thickness = loss tangent of substrate = cartesian co-ordinates = characteristic impedance of quarter-wave transformer line = input impedance of resonator 1