nRF51822+BAL-NRF02D3+Flex PCB+Monopole Antenna

[Bhaskar]

Hi,

I'm designing a 2 layer flex PCB with the nRF51822-CFAC WLCSP package and recommended ST BAL-NRF02D3 balun and i have chosen mono-pole antenna is a good choice,because i have enough room for it on PCB and they are cheap, easy to tune and possibly gives the best performance.

I have a couple of questions :

1. How to calculate minimum length of a mono-pole antenna required on flexi PCB. Is there any reference design document available for antenna length calculation on Flexi PCB( with polyimide dielectric).

2. How to calculate the minimum trace width of the antenna.

I am assuming Antenna length is measured following the antenna from the edge of the ground plane..!!! am i right ?

Please help me on this calculation.

Regards, Bhaskar M

[FormerMember]

1) To find an approximate length of the antenna you need to calculate the wavelength in the flexprint material. When you know the wavelength, divide it by 4 (quarter-wavelength antenna).

2) An antenna trace width of 1.5 mm works fine in FR-4 substrate, so I will assume it works fine on flexprint as well.

3) Yes, the length of the antenna is measured from the edge of the ground plane.