Hi Keiron they ideally have a coax from the antenna to a patch lead which screws into the back of most Samsung phones and many others. If you have a phone without a patch lead port you can put your phone in a dedicated cradle. If you have 1 bar reception an extension antenna will give you 2-3 bars , so it increases reception far beyond the phone only.
Regards Peter

we have 3 nob phones - two are on cheap (other than the Bosses, as she yaps a lot to friends and family each day) from Optus and we also have a Telstra 4G phone which we seldom use, and have on a pre-paid (which we pay just enough on to keep the number active). It is a "rural" phone and has a plug in for its cradle and that is attached to an external, nudge bar mounted 2 metre aerial. It means when our cheaper Optus phones don't work, we can probably get reception in most areas through the Telstra phone. We check the credit on line regularly (it expires every 2 mnths) and just re-new it. It means we can phone family, friends, or emergency serices wherever there is mobile ph service. If you go into non-metro areas, you need to go with Telstra - they have the biggest national covereage (even though theyre the dearest)