Aerial inventory antenna
The present invention relates to radio frequency identification antennae for automatically reading and locating inventory when moved and rotated by an inventory-scanning robot having three dimensions of position mobility.
1. An antenna for scanning RFID transponders, comprising:
a toroidal reflector loop having a diameter about 4.6 inches;
a first helical exciter element having a diameter similar to the toroidal reflector with about 1.2 inches between the turns and located above the reflector loop;
a second helical exciter element having a diameter similar to the toroidal reflector with about 1.2 inches between the turns and located above the first helical exciter element;
a first balun having a balanced port connected to the first helical exciter element;
a second balun having a balanced port connected to the second helical exciter element; and
a toroidal director loop having a diameter about 3.8 inches wherein the director loop is located above the second helical exciter element.
2. The antenna of claim 1 , wherein the reflector, the exciters, and the director are made of 16 AWG brass wire.
3. The antenna of claim 1 , wherein the reflector, the exciters, and the director are made of half-hard brass wire.
4. The antenna of claim 1 , wherein each balun further comprises an impedance-matching circuit attached to their respective unbalanced ports.