Hardware and physical integration guideline PCR Sensor A111
Page 27 of 32
2022-03-08 © 2022 by Acconeer – All rights reserved
Figure 30. Detailed geometry of an FZP lens with quarter wavelength phase correction step.
where
is the radius of each step, s is the thickness of each step, F is the focal point, p is the
number of steps, is the wavelength in free-space (5 mm at 60 GHz), and
is the dielectric
constant of the chosen material at 60 GHz.
By using the equations mentioned above, one concludes that a four-step FZP lens in ABS-M30 plastic
(ε
r
= 2.48), with the focal point at 10mm, needs the following dimensions:
r
1
= 5.1mm
r
2
= 7.46mm
r
3
= 9.39mm
r
4
= 11.12mm
s= 2.17 mm
Total thickness of the lens: 4*2.17 = 8.7 mm
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