Those folding "tape measure" antennas do work very well, and usually can be found for FRS, or GMRS, or Dual band ham (2 meter and 70 CM) HT's (Handie Talkies, hamspeak for a walkie talkie or hand-held radio) for around $14.
I use them on my Yaesu VX5, VX6, VX7, FT60, FT65, FT70 Ham dual band radios.
Remember folks, no matter what band you are on, the sending and receiving antennas both need to be in the same PLANE of existence for maximum transmission/reception range.
For example, two of you talking via a pair of HT's, the antennas should both be Vertical, as most the FRS, GMRS, and Ham radio HTs are all FM (Frequency Modulation) transmission mode. FM doesn't really work all that well at low power in a horizontally polarized transmission mode, so the antennas should be held up vertically, that is, perpendicular to the earth's surface at both the sending and receiving end.
If one is vertical and the other horizontal (Like you see the "cool" folks on TV shows doing all the time) then the signal interception area is very, very small, basically the area where a vertical stick and a horizontal stick would meet to form a cross.
If both antennas are in the same plane, then the signal capture area of the antennas matches, and you get a much stronger signal, and you are able to converse over a longer distance.
Another trick to remember is that you are the GROUND PLANE when using a HT.
A radio signal needs a Ground Plane to be effective and carry as far as possible.
Think of it this way, an astronaut in space steps out of the space station air lock with a jump, and he travels a little way from the space station due to the initial thrust he gave himself with his last foot contact with the space station.
If the area his foot made contact with as he thrust was only the size of his big toe, and was a slippery, greased surface as well, he doesn't get much thrust, but if he had both feet firmly planted against a gritty surface that gave him maximum traction, he gets more of a launch and goes further.
Once in free space, and he comes to a stop when that initial thrust is exhausted, how far out in space is based on how much of a launch he got. Now he starts pumping his legs, running like Usain Bolt at the Olympics.
What happens, does he move fast through space? Nope, he stays right where he is, because there is no GROUND beneath his feet to give him traction to gain any more thrust.
That's an RF signal without a GROUND PLANE, it has some initial thrust, and does travel a ways, but not as far as it would if it had a larger traction area under its feet at that initial thrust. And the greater its initial "launch" thrust, the further it travels before it runs out of steam.
So, what can you go with an HT to give your signal more "thrust"?
You are the ground plane when you hold the HT in your hand while transmitting, via capacitive coupling between your palm and the HT's case.
But if you take a length of fine wire, 22 gauge or smaller (26-30 gauge works well), and you do a bit of math, you can add a great ground plane to your HT and increase the signal strength and distance it will travel in transmit mode.
You need to know the frequency you are transmitting on, well, really just the band limits, upper and lower.
Then pick a frequency in the middle of that band to work with.
For example, let's use the 2-meter ham band, runs from 144.000 to 148.000 MHz
So, we pick the middle, 146.00 MHz
We calculate how long a full wavelength is at that frequency by dividing the number 936 by the frequency in MHz, so 936 divided by 146.000 is 6.41 feet, that's the length of a full wave antenna for 146 MHz
A Half Wave antenna would be 468 divided by the frequency, a Quarter Wave antenna would be 234 divided by the frequency, and an Eighth Wave antenna length would be 117 divided by the frequency.
Most HT's come with an Eighth Wave antenna commonly called a " Rubber Duck", little bitty stubby S.OB. that really limits transmission range, so most Hams will upgrade to a Quarter Wave Super Rubber Duck antenna.
The Rubber Duck is usually about 9.6 inches long, and there are some that will wind a lot of wire into that length and call it a Quarter wave antenna instead of an Eighth Wave, because the total length of the wire wound around it is equal to 19.3 inches, which is what a wire antenna of Quarter Wavelength at 146.000 MHz would measure if stretched out straight. It does work a bit better than a standard Rubber Duck with a wire length of only 9.6 inches, but not all that much.
The Super Rubber Ducks will be about 19.2 inches long, and while that is a Quarter Wavelength at that frequency, they are often wound with enough wire to actually be a half wavelength or even 5/8ths wavelength long.
The Tape Measure folding antennas mentioned above are 5/8ths wavelength when fully deployed by the way.
Well, none of these still has any ground plane other that your sweaty palm and water filled body.
So, figure out find out how long your antenna is according to the manufacturer (they should be able to tell you if it's a 1/8, 1/4, 1/2or 5/8ths), and then do the math to figure out how long that is in inches.
Take that number and multiply it by 1.05.
That's how long a good ground plane should be.
Cut a piece of that small gauge wire to that length, plus 1 inch.
Strip the last 1 inch of that wire bare of insulation, take the antenna off your HT, and wrap the bare wire in a circle around the bare metal threads where your antenna screws onto the HT.
Put the antenna back on.
Let the wire hang down the side of the HT so that it points towards the ground while the antenna is vertical.
Now you have a great ground plane, your sweaty palm and water filled body (which actually absorbs some of the RF radiation as well as reflecting it) and a ground plane that is 5% larger than your antenna radiating surface.
You just turned that vertical antenna into a dipole, which radiates much more efficiently during transmit than does the vertical by itself with you as the sole source of grounding.
Any questions?
Fine, take-out pencil and paper and prepare for the pop quiz.
What, you didn't know there was going to be a quiz?!! There ain't no free lunch, there is always a pop quiz.
Today's question:
What is Tophog's favorite brand of whiskey, beyond the 23 Packard Deluxe he and I make in our still I mean, the store-bought stuff he consumes when he forces himself to go into town and into the store, what brand is that?