transmit to a central receiver to provide localized detection along predetermined segments of the picket barrier fence in fig2 a a possible modification of the pickets 10 is shown in this embodiment each of the pickets 20 are provided with vertically extending ribs 22 which are welded to or otherwise affixed to the sides of each picket and are made saw toothed in configuration to discourage climbing of the fence in addition the tips of the saw toothed ribs may be bent slightly forward or rearward to more readily catch onto the clothing or flesh of one attempting to violate the barrier in fig2 b another possible modification of the pickets 24 is shown and includes a triangularly shaped member 26 which is attached to each picket midway along its length alternatively two of the members 26 could be attached to opposite sides of every other picket as suggested by the dashed lines 26 39 the purpose of the members 26 is to provide limit stops which restrict the potential deflection of the pickets to only slightly more than that required to actuate an internal sensor element it will of course be appreciated that numerous other alternative picket designs could also be used one design particularly suited to high security application is the 34 candy cane 34 configured top turning now to fig3 and 4 details of.