AN3394

Main criteria for key antenna design

Doc ID 018754 Rev 5

19/29

4.3

Inductance of a square antenna

Equation 3

, where:

●

●

●

K1 and K2 depend on the layout (refer to Table 1 for values)

Figure 18.

Square antennas

4.4

ST antenna calculation tool

ST provides a simplified software tool (antenne.exe) to compute rectangular planar antenna

inductances. This tool gives good approximations of the inductance value. It is

recommended to verify the obtained results.

ST tool is based on the Grover method (see Equation 4.1: Grover method).

Equation 4.1: Grover method

, where:

●

M is the mutual inductance between each of the antenna segments

●

Equation 4.2

, where:

●

s is the number of segments

●

Table 1.

K1 and K2 values depending on layout

Layout

K1

K2

Square

2.34

2.75

Hexagonal

2.33

3.82

Octagonal

2.25

3.55

L

ant

K1

μ

0

×

N

2

×

d

ant

1K2 p

⋅

+

-------------------------

×

=

L

ant

L

0

M

∑

+

=

L

0

L

j

j1

=

s

∑

=