Plastic enclosure over reference design

[Victor Nascimento]

How does a Plastic enclosure affects the performance of my RF antenna?

I'm designing the PCB + housing and as it have to be small, i'd rather use a BALUN + Chip antenna to save space. As I am a undergrad student, anyone with more experience can help me on this?

Thanks in advance

[Locky]

Typically it will cause loading, which will shift your matching center frequency down. You will need to adjust your matching circuit to offset the center frequency above 2.45Ghz. That way when you place it in the enclosure it will center

[Victor Nascimento]

But in this case, my matching circuit is done by the BALUN, right? Do some extruded cuts near the antenna make any difference (like holes)?

[Locky]

The balun is only for providing a Single-Ended Signal from the Chip to the Antenna. However due to your PCB and Enclosure there will be additional loading seen by the antenna. Therefore it is always recommended you have a Pi-Network between your Balun and Antenna to further match Antenna to the PCB. This will also allow you to adjust your center frequency to offset for the detuning of the plastic enclosure.

[Victor Nascimento]

But then, whats the advantage of having a BALUN?

[Locky]

I balun is simply for converting the Differential RF signal into a single-ended signal. Though it is matched to the chip, your Antenna is not matched to the PCB. Therefore you need a Pi or T matching network between your antenna and balun