Build A Simple VHF/UHF "Scanner" Radio Antenna
Build a Police Scanner Antenna for the price of parts!
Here is a simple VHF/UHF scanner radio antenna you can build using very inexpensive coaxial cable and a few parts plus some bits of wire!
It should cover receiving only from the AM aircraft band up thru the most used UHF frequencies in use by the average "police" type scanner radio you may have. If you live in a large metropolitan area, it should work well way beyond the UHF action frequencies also.
It's design is based on a standard "ground plane" type antenna and the "harmonic" principle of antennas which means that is was designed for the VHF band but due to the characteristics of the way antennas work, it will also work well on it's third harmonic of the design frequency band.
The UHF scanner radio band is approximately 3 times higher in frequency than the VHF scanner band so it's design will work well there using only one length rather than several lengths in the vertical portion of the antenna to cover the VHF/UHF radio bands. This antenna has NO gain on VHF, but does have a little on UHF due to being operated in the "harmonic" mode on these frequencies. Many Amateur radio antennas are based on the exact same design and have been used effectively for many years. Compared with the commercially produced antennas, with their cost as a big factor, it does perform well for "pennies" on the dollar!
(Simple VHF/UHF scanner antenna made from coaxial cable)
This antenna is designed to be "cheap". So it must be constructed in such a way to be supported from the top of the vertical "element" of the antenna and also from the ends of the 3 "radials" that go away from the coaxial cable at it's junction. One good way to suspend the vertical section is to make a small loop on the end of the vertical section and suspend it from a small non-conductive rope, cord or heavy string from something above. Make the length of the cord, rope, string, etc as long as needed to get the vertical section and the radials portion at least 3 or 4 feet away from any large metal surface like house siding, roofing material, etc.
DANGER!DO NOT HANG OR MOUNT IT NEAR POWER LINES!
The antenna must be in the vertical position, meaning that the tip of the vertical portion away from the coaxial cable must be up towards the sky.
The 3 radials may be done the same way as the vertical section. Just make a small loop on the ends of all 3 and tie them off in 3 equal directions with the angle about 45 degrees down from horizontal, similar to the simple drawing below:
1. Coaxial cable. Should be any usable cable such as TV type or 50 ohm coax. Coaxial cable comes in many different types, but as a general rule for receive only functions, the TV type coax will work fine and is easy to find. Some TV types have an inner foil and the shield, which makes working with it a bit more difficult. You can not solder to the foil, only the shield! You will need enough coaxial cable to hang the finished antenna OUTSIDE and above the roof if possible. It can be used inside with reduced performance by hanging it from the ceiling near a window.
2. Wire for the radials. Final length....About 20 inches each (3 pieces) #12 or #14 works well and is more stiff than smaller wire size. See hints below!
3. Wire for the vertical section. Actually, this wire will come from within the coaxial cable by removing the outer insulation and the shield...see constructions tips below.
4. Soldering gun or iron, solder and sealer for the coax radial junction. This keeps the rain out and is very important.
5. Assorted hand tools, sharp knife for trimming insulation from coaxial cable.
All of these parts and tools can be found at any hardware shop or electronic store. However, building this should be easier and cheaper than repairing a Ford F150, however it shouldn't cost you an arm or a leg for parts.
Construction and tips for building and using it.
In the drawing above, you will see the black section representing the coaxial cable.
You will also see the vertical section (A) on top.
You also should see the 3 radials marked (B) hanging down.
One of the best ways to construct the scanner antenna is to take your full length of coax and remove the outer insulation AND the shield for about 21 or 22 inches from one end leaving the inner wire exposed with it's insulation intact. DO NOT CUT INTO THE INNER WIRE inside the coaxial cable. If you cut it into, you will have to start all over! The idea here is to leave about 21 to 22 inches of the center conductor (wire) exposed with it's insulation intact after you remove the other section containing the outer insulation and the shield. You also need to leave about 1 inch of the shield exposed for soldering of the 3 radials to it! Refer to the drawing above.
Now take a close look at where the black portion of the coaxial cable ends in the center of the drawing. This is the point where the 3 radials are physically and electrically attached to the shield of the coax that has been exposed.
They should be soldered to the shield being careful not to destroy the insulation for the "center" conductor of the coaxial cable. These 3 radials in NO WAY should be attached to the center conductor (wire) that is inside the cable. If this happens, then the antenna will become useless! See the drawing.
Make sure you leave the insulation on the center wire until after you are done with the construction OR as an option, you may just leave it on to help protect the wire inside it from the ravages of moisture, corrosion, etc, but remember you have to make a loop on it's end for hanging (by tahir). Leaving the insulation on will in no way effect the performance of the antenna!
The 3 radials need not be soldered in 3 different places on the coax shield unless you want to go to the trouble of doing this...here is another way to attach the radials.
Simply just attach one, by adding enough extra length to it to wrap around the shield and then solder it to the shield. Then just solder the other 2 to that single radial close to the shield and then you can spread them out in 3 equal directions from the coaxial cable of the antenna looking down (Birds eye view) on it from the top. To be technical, each one should spread out at 120 degrees, but they don't have to be perfect!
So...after you have completed this simple scanner antenna, all you have to do is hang it suspended from your support, attach the opposite end to your scanner radio using the correct connector and enjoy!
For more ideas on ways to help make a more sturdy scanner antenna, just take a look at how Amateur radio operators do it using PVC! The basic design is the same, just a different way of using ham radio ingenuity! Click Here!
If you don't have the skills or just don't want to build a good scanner antenna, then check out Scanner Master for all your Scanner antenna and radio needs below.
Base and Mobile Police Scanner Radios From Scanner Master!
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