Jack// ani said:
Hi all,
Why is RF circuit shielded inside a metal case...like a cell phone,
where whole of the pcb and its components are shielded.
Five reasons I can think of:
1. To stop unwanted radiation exiting the device, possibly interfering with
other devices (eg, local oscillators, unwanted mixing products, harmonics);
2. To prevent unwanted radiation from external devices affecting the device
(eg mixing products and image rejection, and for devices using external
antennas almost any digital device, and some analogue ones, in your
domicile);
3. To stop subsytems within the device interfering with each other (eg,
self-oscillation, unwanted mixing products).
4. Increased surface area decreasing the resistance due to skin effect.
5. Maintaining correct impedance in transmission lines.
Cheers, Howard