substrate and corresponding local demetallization slightly larger than the ground plane the antenna is therefore fed at its center directly by the coaxial feeder cable to ensure symmetrical and in phase feeding of the various dipoles fig1 shows that the two groups of dipoles have a small center distance of axes d the center distance of axes d aligns the phase centers of the dipoles of the two groups to compensate their slight offset due to the effect of the ground plane on the dipoles the value of the center distance of axes is very small of the order of a few millimeters it depends on the operating frequency of the antenna and is in practice adjusted as a function thereof the center distance of axes adjusted in this way minimizes fluctuation affecting the signal radiated by the antenna reducing it to less than 2 db relative to the maximum radiation from the antenna the antenna is mounted in a protective radome not shown but of the kind routinely used the cylindrical radome can have a lightning arrestor spike connected by a section of cable to the ground plane of the antenna fig3 shows the radiation diagram of the antenna in azimuth to a scale of 5 db per division it shows that its radiation in azimuth is quasi omnidirectional having only small fluctuations that are limited and less than 2 db relative to the maximum radiation on both sides of the antenna corresponding to the angular positions designated 90 u00b0 and u2212 90 u00b0 fig4 shows how the vertical polarization of the signal radiated by the antenna is obtained resulting from.