nRF51822 with aluminum enclosure (Partially Metal Enclosure).

[Asmat Ali]

Hi..

I am using NRF51822 , we are using Ceramic antenna. We are thinking of designing body similar to the image. perimeter of the body is made of metal (aluminum) of thickness 1.5mm and width 10mm but other parts of the body will be plastic. Can we get max range if we use such design? how much range should we probably get on the sides? Ceramic antenna is omni directional.

if you Cannot See Image.. Pleas open below Link. drive.google.com/.../view

[Jørn]

Hello Asmat Ali

As was mentioned in devzone.nordicsemi.com/.../ Aluminium behaves as a reflector, which blocks the electromagnetic waves incident on it. Some of the signal might still make its way around via diffraction, depending on the shape of the structure edge, but it will be attenuated.

The behavior of an antenna is dependent on the antenna itself, and its surroundings. The aluminium walls can affect both radiation pattern and load impedance of the antenna, the latter can cause mismatch with your amplifier, which in turn can affect your maximum range. There are many factors involved such as the geometry of the antenna, the location of the antenna compared to the metal structure and orientation of the antenna to name a few.

In the far field the electromagnetic signal will be the sum the signal taking the direct path from your antenna, and those that are reflected by the casing and your surroundings. All of this makes it very difficult to make an assessment on how the casing will affect your range. A safer approach would be to use a simulation software with a 3D model of your casing, or build a prototype and perform tests.

Best regards

Jørn Frøysa

[Asmat Ali]

Hi Jorn.. Thank you for Immediate Replay.. Actually if we want to stick with this kind of Design of Enclosure.. Then What We need to change in PCB Or in Metal Case to maximize the RF perfomance. We are Redy to change in Enclosre and PCB. But We Stick with this Aluminium Design...