Manual

Proximity to Metal Objects
bcant-an-001Pa
© Copyright CSR 2003
This material is subject to CSR’s non-disclosure agreement.
Page 7 of 14
BlueCore
™
Inverted-F and Meander Line Antennas
5 Proximity to Metal Objects
CSR recommends keeping metal objects as far away from the antenna as possible. Keeping metallic objects out
of the near field is usually adequate.
Near Field = 2D
2
/ λ
D is the largest dimension of the antenna. In the case of these antennas, this is approximately a
quarterwave (λ/4).
Notes:
λ is the wavelength of the signal in freespace.
At Bluetooth frequencies, λ=122mm in freespace.
Substituting D=λ/4 into the Near Field equation gives Near Field = λ/8.
Near Field = 122/8 mm = 15.25mm.