Cell phone antenna

[Walter Wayne]

Even weirder is the 'patch antenna'. Just a rectangular piece of circuit board, with a contact off center. Seems the ratio of thickness between the layers of plating on each side and the size makes for tuning to a particular wavelength. It's how GPS works. Probably other high freq stuff like phones too. I wouldn't be surprised to dissassemble a phone and find nuthin linked to the extendible antenna, it's just a gimmick that the customer can fiddle with.

Patch antennas are used because they have a nice broad pattern to one side. That is, if you lie it flat with the patch side facing up it has good performance straight up and extending down towards the horizon, where it drops off and receives almost nothing at the horizon and below. Since satellites tend not to be near ground level in the same way that cell-phone base stations are, a patch antenna is good for many satellite applications like GPS. Incidently, one tends to get your poorest GPS performance when the only visible satellites are all low in the sky.

The patch is tuned to a frequency by its length, though the material characteristics and thickness will modify the optimal length somewhat.

Walt

 

[CaveDave]

I knew you were going to say that .

Yuri

Did you steal my hat?

I've heard storys about you Voodoo Veterinarians, but I had refused to believe them...

...until now.

Cheers,
Dave

 

[Jon the Geek]

My sister used to be an engineer at Motorola, and told me once that the purpose of the pull-out antennae was to reassure people who thought cellphones should have antennae outside of the phone herself. That was all. According to her, it did nothing, or at least its affect was so neglible that moving around made far bigger differences.

 

[macgyver]

My sister used to be an engineer at Motorola, and told me once that the purpose of the pull-out antennae was to reassure people who thought cellphones should have antennae outside of the phone herself. That was all. According to her, it did nothing, or at least its affect was so neglible that moving around made far bigger differences.

Well that seems plausible as well. I was only guessing that the antenna was functional. In this case the aesthetics are reversed!

This might also explain why many of the newer Moto phones have dispensed with the pull out all together.

I have an Audiovox, and I'm suspicious of it's pull out antenna functionallity. It appears to just be a plastic rod that doesn't have any electrical connection to the phone! Maybe the same idea as what you mentioned?