AN2731 Freescale Semiconductor / Motorola, AN2731 Datasheet - Page 5

Manufacturer Part Number

AN2731

Description

Compact, Integrated Antennas: Designs and Applications for the MC13191 and MC13192

Manufacturer

Freescale Semiconductor / Motorola

Datasheet

1.AN2731.pdf (26 pages)

In general, the smaller the antenna, the lower the radiation resistance and the lower the efficiency. The

antenna should also be removed somewhat from the ground plane, preferably at least ¼ wavelength (3 cm)

but not less than 1 cm.

ground plane, or even loaded with small capacitors to ground. This technique shorts the dipole considerably but

causes heavy RF currents to flow in the ground plane, resulting in low efficiency. Often some of the other loading

techniques result in better performance.

Freescale Semiconductor

Sometimes a loading technique is employed where the dipole ends are bent close to the

Figure 3. Dipole Loading Examples

Compact Integrated Antennas, Rev. 1.2

Hairpin Loading

Inductive Loading

Meander Pattern

Folding

Basic Antenna Theory