Homemade iPhone 5 antenna

[darkernite]

Hi guys,

I'm like to go wild camping and trekking and often find myself in remote areas without reception. It would be handy to have reception particularly to use GPS based apps. I was wondering if anyone knows how I could go about making and attaching an antenna to my iPhone 5. I've seen a lot of videos which suggest an antenna based on wavelength, but they suggest attaching the antenna to a port the iPhone doesn't have. Does anyone have any suggestions?

 

[VEBill]

You can closely couple the iPhones built-in antenna to effectively make a transformer connection to an external connector. It would be tricky to make it work optimally over the various bands that might be used. Somebody must sell such a docking antenna coupler by now; I've seen them for various phones over the years. They'd work about half as good as you might hope (maybe worse). Plus you'll need a high gain antenna. And expensive coax cable. And it still might not get you a signal where there's no signal at all.

It would a lot easier to simply download the map tiles in advance, while you're still at a wifi hotspot or within cellular coverage. Many GPS apps provide this facility to download the maps that you'll need in advance. I do this all the time, traveling to UK and Asia. Works perfectly.

What others may neglect to tell you, but I will, is that an iPhone using GPS continuously will have a flat battery in about two hours. A $99 dedicated GPS can go for 12 or more hours on two AA cells.

 

[Comcokid]

Look at how a Yagi antenna is formed, with a driven element, back reflector element and maybe a couple forward elements. Now visualize your iPhone with internal antenna as the driven element. You could even arrange this as thin strips of aluminum foil taped to a piece of cardboard with a magic-marker outline of where to place the phone.

Now, I've not tried this with a phone before, but have done this with plenty of ISM band wireless devices and you can quickly get 6 db or more of improvement if you know which direction the service providers cell phone tower is.

However note this - cell phone towers determine the range to the phone by measuring the time for a (control handshake) signal to be sent to the phone and for the phone to reply. If the distance is too far the cell tower will resuse to connect even if you have good signal strength. I've seen this happen in the Smoky Mountains of East TN.

 

[Higgler]

comcokid's answer is reasonable and lightweight.
You could try a simple reflector design and get more gain depending on reflector size. How you'd make it for hiking convenience is the challenging part (rolled up wire/metal mesh screen door? use reflector curved in the horizontal plane only would make it simpler?)
You should know where the cell towers are relative to you knowing GPS coordinates and use a compass to set the cell phone/reflector in the correct direction.
Interesting note on the time delay measurement Comcokid. Makes sense, long range calls slow thruput.

 

[Comcokid]

Cell towers range to the phone to determine if the phone is actually wthin that particular towers 'cell'. The system doesn't want more than one tower, or more than one cellular network to service a phone, otherwise the whole system would quickly jam-up and collapse. This ranging is also how a cell phone can be located and tracked +/- a few hundred yards even without GPS.