Directional wire antennas for use in article or personal tracking and/or inventory monitoring or control systems wherein the antennas are specifically configured to provide a tunable vertical beam angle which is less than their horizontal beam angle. The antennas are modified or non-balanced dipole or monopole structures having non-symmetrical wire legs wherein at least one leg has segments extending angularly in a linear manner in two separate planes. In preferred embodiments the antennas are designed to receive signals from active RFID (radio frequency identification) tags placed on objects to be monitored within confined or defined structures without bleed over of signals from tags placed on objects at different vertical levels of the structure.