Sunday, June 15, 2008

Got a Samsung SCH-i760? Don't use an external antenna!

If you have a Samsung smartphone, such as the SCH-i730 or SCH-i760, you may or may not be aware that there is an external antenna jack on the back of this phone (you have to pop off a small round cap to see it).

It is possible to use this jack to plug in an external cell phone antenna - an incredibly convenient option for road warriors who can't afford to drop calls when traveling through spotty areas, etc. However, I have this cautionary tale to share with you.

This is the 3rd time I have had my cell phone replaced because the internal antenna performance degrade to almost nothing. It started with my Samsung SCH-i730, and then when I upgraded to the SCH-i760, it happened twice. I have decided that the issue is likely one of the following:

1. Samsung makes a flaky and weak connector, which breaks the internal antenna connection when used (doesn't really make sense, as the external antenna still works)

2. I have been unlucky enough to get 3 defective phones (yeah, right.)

3. The external antenna is BURNING OUT the internal antenna, due to a design problem with the Samsung phones.

4. The internal antenna is BURNING OUT, due to a design problem with the external antenna.

In circumstance 3 & 4, a little bit of radio theory applies here: When you plug in an external antenna, it doesn't take the internal one out of the circuit. Rather, the 2 antennae are in parallel, and untuned. This creates a high SWR (standing wave ratio) situation that the fragile internal antenna (probably a just a "coil" drawing on a circuit board) can't handle.

If this is the case, Verizon should do a better job of notifying users that this jack is for the testing bench only, and not for use with an external antenna. After all, it's pretty easy to come by an aftermarket adapter that fits this jack, advertised for use with an external antenna. Verizon sales people will not warn you against using this jack with an external antenna.

It could be a problem specific to my external antenna, but when searching I found 2 posts indicating others have had this problem:

Post #1
Post #2

Finally, I just found a blog post with a definitive link to a faq on Samsung's website about this. The jack is not for use with an external antenna!
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