Antennas are available in different form factors and sizes; They can be integrated in a doorframe (gate), to read transponder data from entering personnel or ojects. Implemeted in toll systems, they can be used to monitor traffic on the motorway as well. The electromagnetic field that is created by the antenna can be sustained permanently if transponders are passing by all the time. Alternatively if is not necessary that the field is online all the time it can be activated through a sensor.