Radio antennas?

Question

Why are handheld radios(FRS, CB, Amateur) antennas just one wire? How can that work to receive and transmit if it’s just one wire? I mean the antenna should be TWO wires, just like the antennas on the big stations, or the TV antennas. It should be a closed circuit((- and +) OR (- and ground)?).

That brings me to my next question:
I have a FRS radio. I used a TV antenna cable, and connected the radio wire to the inside wire of the cable. The cable goes up to my roof, which is only about 40 feet high, but did not work at all. If I go to the top of the roof with the radio on my hand the reception/transmission is great, HOW CAN I EXTEND THE SHORT FRS ANTENNA TO THE ROOF IN AN EFFECTIVE WAY, JUST LIKE IF I WAS UP ON THE ROOF WITH THE RADIO ON MY HAND???

Answer 1

FRS radios are not allowed to have external antennas, and their maximum power is limited to half a watt.
A GMRS radio is identical to an FRS radio - it uses the same frequencies. But it might have two important differences.

The first difference is that it might be higher powered than the FRS radio. extra power does not always automatically mean extra range, so don't be too excited by the extra power that a GMRS radio offers. All that extra power really means is your batteries won't last as long!!!

The second difference is that the GMRS radio can have an external antenna.Generally it seems that manufacturers claim an 'up to 2 mile' range for FRS radios and an 'up to 5-7 mile' range for GMRS radios (with built in antennas) and then claim 'boosts range by up to 75%' for an external antenna add-on. So, this would suggest a best case range of about 12.25 miles for a moderately low powered GMRS radio with a 'normal' non-directional antenna.