rf shields The solutions to RF Shields for 3G mobile phones

[kynix]

I am an electronic engineer, always making different various projects and thinking about solutions to different questions. Today, I am going to make an electronic project related to RF shields for 3G mobile phones. 

 

Here are my following projects:

 

The cellular transmitter module will generate the maximum radiated power for any component in the handset, which may induce EMI and RFI. Similar problems can be used to reduce RF and EMI associated with EMI and RFI The sensitivity to external magnetic fields can be minimized.

 

So, what kind of shielding design method has the best efficiency? This three-part series discusses the effective RF shielding method around today's cellular transmitter modules.

In recent years, mobile phones in the form, function, performance and cost have undergone tremendous changes. The evolving new technology has spawned smaller, more energy efficient and highly integrated semiconductor devices that continue to produce more portable (mobile) mobile products with more integrated levels.

 

Operators are providing additional services such as SMS (SMS), multimedia (MMS) and GPS, while manufacturers add additional wireless features such as FM radio and other functions for mobile cellular phones, as well as MP3 players and digital cameras. Achieving all of these features requires a form factor and volume that poses a challenge to handset designers and hardware engineers.

 

As a result, handset designers working on printed circuit board (PCB) levels are experiencing undesirable core issues such as coupling, coupling, and crosstalk between integrated devices. And all of these problems led to more design rework, the lack of versatility between the phone profile and the extended design cycle, and these have increased the cost of mobile phone development. In today's competitive market pressures, these factors play a key role in the success of mobile handset manufacturers and designers who develop them.

 

One area in the early stages of handset design that could help solve these core problems is the widespread use of the shield. Shields reduce electromagnetic interference (EMI) and radio frequency interference (RFI), greatly weakening the unwanted radiation, alleviating the disaster it caused. At present, shielding and RF frequencies go hand in hand, because all RF communication standards have some requirement to minimize unwanted radiation.

 

The effectiveness of the shield is characterized by its ability to attenuate the radiation signal in a wide spectral range. For example, a metal "container" with a movable cover may constitute a shield, or the container itself may be directly welded to the PCB. The use of a cover structure is useful for regulation, so it is often used in TV tuners and other applications, but the effectiveness of the shield is highly dependent on the electrical connection between the cover and the container.

 

It is based on the basic concept of RF shielding: time-varying electromagnetic field (EM) will be in the conductor around the field line induced current. Therefore, the induced current in the perfect conductor will produce an EM field opposite to the evoked field, thereby canceling the field lines within the conductor. Therefore, shielding too many holes, grooves and openings will reduce the shielding effectiveness, which is due to the induced current can only exist in the conductor of free electrons flow.

 

The opening on the conductor (container) means that there is no free electron there, which causes the current to flow along other paths along the opening, so that the induction field can not completely counteract the evoked field.

 

The skin depth is another important factor, which is determined by the ability of the EM wave to penetrate the conductive membrane. In particular, when the low frequency is of particular importance, a thicker film will be required for effective shielding of the RF signal.

 

Based on my project, I outlined a circuit and after testing over and over again, it worked well in the end.

 

 

Ps: Excuse me if I was wrong improperly in words or expressions. I am a green hand in electronic engineerings. I need continual learnings. 

 

Those are just my understandings. What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated.

 

May someone would like to help ?

 

thanks in advance.