Hi guys

I have this question, it's not a project I am working on.

I played around with a few RF module, 900Mhz one and 2.4GHz one. The signal seems to drop if I place it in my palm or in my pocket, compare to placing it on a desk. For me, human body seems to have some negative effect on RF signal.

My question is, how modem mobile phone deal with this? I mean most of the people put their mobile phone in their pockets right? The design of mobile phone antenna must know that, and what do they come up with do deal with this signal drop. Or what can they do to minimise the negative effect?

Thanks guys!

 

Have you heard of the infamous iphone 4? When you held that phone in a particular way you would loose the GSM signal and the call would be dropped. Manufacturers don´t really deal with this in the way of circuits and antennas, I´d say they just place them in the best possible location to get good reception while calling, and try to avoid the metal parts covering it.
Remember how just a few years ago all metal phones had plastic top halfs above the display and bottom halfs, and the rest was metal? That is where the antennas were located.. Now you get more glass all over the phone, so the attenuation of the metal is not such an issue.
But of course the antennas in phones will be fine tuned to the typical use conditions, so the GSM antenna would be prepared to cope with your ear and hand being close, while the GPS antenna would probably expect that you hold your phone in your palm and the display points upwards for the best reception.

The secondary improvements are probably in the noise floor of the receiver, so that it can get good reception even with very low input levels.

 

You can't design an antenna which isn't affected by its surroundings. The signal level will change depending on what is around the antenna. The base station tells the phone what power level it should use to keep good reception.

 

Have you heard of the infamous iphone 4? When you held that phone in a particular way you would loose the GSM signal and the call would be dropped.

You're right about the iphone 4. I got one which is worse. I have to bring it near to my WiFi modem when I want to use WhatApps.....

ALlen