Physical Principles of RFID Systems - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 128

Emitter element

Metallisation

Substrate

Power supply

Figure 4.71 Supply of a λ/ 2 emitter quad of a patch antenna via the supply line on the reverse

x = l /2 − h D
y

= l /2 + h D

x y

Figure 4.72 The interconnection of patch elements to form a group increases the directional
effect and gain of the antenna

individual elements is guaranteed. The arrangement is polarised in the direction of the
line sections.

4.2.5.9 Slot antennas

If we cut a strip of length λ/ 2 out of the centre of a large metal surface the slot can be
used as an emitter (Rothammel, 1981). The width of the slot must be small in relation
to its length. The base point of the emitter is located at the mid-point of its longitudinal
side (Figure 4.73).