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Improve FM Signal on Radio with a Single Wire Antenna

Many older radios and emergency radios have a single wire antenna. The single wire antenna is a short metal stick that pivots on a receiver base that is screwed into the top or back of the radio. This metal stick might telescope out, making it longer and improving the reception of radio waves. 

There are several ways to improve the FM signal on a single wire antenna radio. You can enhance the FM signal strength by repositioning the radio, making a Dipole antenna, or extending the existing antenna. All of these are do-it-yourself options, but they vary in difficulty level. Read on to learn how to improve FM radio with a single wire antenna. Your options below fluctuate between simple and difficult, with great and inconsistent results.

Understand the Basics of FM Radio Signals

The frequency modulating (FM) form of radio signals was invented in 1933 by Edwin Armstrong. Because the frequency of the audio signals is not subject to fluctuation, it is less susceptible to atmospheric interference than AM radio signals. The problem with FM radio is that it is broadcast in a straight line. This means that it is subject to interruption from many things:

  • Heavy forestation
  • Large buildings
  • Landforms such as hills and mountains
  • Interfering devices such as TV signals, washing machines and other appliances, hairdryers, computers, baby monitors, and anything else that may be plugged in and operating at the same time.
  • Interior wiring in the walls or attic may interfere with FM signals.

These things interfere because often other wires act as antennas that pick up the FM signals before they can get to your radio. Other times, they break up the signals and pass along static. Usually, the source of severe interference can be located by tuning the radio to a low AM station and moving the radio toward suspected sources. The static will get much stronger when it comes to an interfering appliance or wire.

Improve FM Signal on Radio with a Single Wire Antenna

1. Reposition the Radio

Before making a new antenna for the radio, move it all around the building and see if there is a better place for the reception. If you know where the FM transmitter or relay is located, point the FM antenna toward it as much as possible. 

  • Higher is always better. The radio antenna may pick up signals when it is located near the ceiling or in a window sill.
  • Closer to a wall or window is better because there are fewer objects to block the FM signals.
  • Rotate the antenna around at each spot to see if there is an increase in signal strength from any point in that location.
  • Put the radio on its electrical outlet. Anything that shares an outlet with an FM radio may also create interference with the signal.

Often, the FM signal can be improved by simply placing the radio in a different location that is higher up inside the building. This is not always possible, especially for those in basement locations where the FM signal is notoriously bad. In this case, an antenna must be constructed and placed in an area with maximum exposure to FM signals.

2. Determine the Type of Antenna on the Radio

This does not affect the construction of an antenna but how you will attach it when you are done. There are several types of antennae on radios, and this does have a big impact on how well it picks up FM signals.

  • Your radio may have a couple of screws on the back that are labeled “ant 300 ohms.” 
  • Alternatively, it may have a coaxial type connector. This is a small metal pin inside of a metal ring. It looks similar to a TV cable connector. 
  • It could also have a single antenna rod attached.
  • Or, the antenna may be completely internal to the unit. This is the most challenging type of radio to fix, but there are a couple of options.

There are two options to fix the reception on the radio, such as a clock radio that does not have an external antenna. 

First, unscrew the radio cover and carefully locate the antenna wire that is looped around inside the case. Untangle it and stretch it out inside the room, going up toward the ceiling. This should improve the signal.

Secondly, if you do not want to open the radio, try wrapping an insulated wire around the body of the radio in as many loops as possible. This may help to pick up more FM signals, boosting the reception to the internal antenna receiver.

Thirdly, a dipole or other style of the antenna can be attached to the newly exposed antenna wire. 

3. Make a Dipole Antenna

Any wire can be used to make a dipole antenna, but speaker wire will give the best results. Speaker wire is an insulated twisted copper wire that is made of two joined strands. 

  • Cut a length of speaker wire that will accommodate the height of the antenna that you need, plus 60 inches to make the T part of the dipole antenna.
  • Split the two insulated strands apart so that every single strand is 29 inches long. This length is needed to obtain the frequencies of most FM stations. For higher band FM, you may need to shorten the length of each side of the T. 
  • Separate them so that the wire makes a large T shape.
  • Use a cable tie or twist tie to clip the section that comes together to form the long base of the T so that it can not split apart further.
  • Place the T part of the antenna as high on the ceiling as possible.
  • Run the long part of the wire to the antenna on the radio.
  • Strip the end of the joined speaker wire up several inches. This exposed wire should be wrapped carefully to the antenna screws to help minimize interference.
  • For two screws, wrap one side of the antenna wire to one screw and the second antenna wire to the second screw.
  • For a coaxial type connection, wrap one wire around the tiny metal pole in the middle. Wrap the second wire securely around the outer ring.

This dipole antenna can be spread along with a window frame if the window is aluminum, wrapped along a long curtain rod, or taped up in the ceiling. If you have easy attic access, it can be run inside the attic. Just be sure that it will not receive interference or signal loss from competing for wiring.

Make an Antenna From a Single Wire

If you have a single wire available, then a loop antenna can be made from it. The larger the loop, the better the reception.

  • Make a wooden X shape from lightweight wood pieces. 
  • Strip the insulation from both ends of the single wire.
  • Attach one end of the wire to the inside of the coaxial receiver or one screw of the antenna receiver.
  • Affix the wire to the wooden X shape, going around the ends to make a large square.
  • Attach the other end of the wire to the outside of the coaxial receiver or the other screw of the antenna receiver.

This type of antenna can be mounted directly to a wall, or looped over a curtain rod or similar structure to make the loop. The key is to get a good connection to both poles of the antenna receiver.

4. Extend the Existing Antenna

Most radios have an existing antenna of some sort that can be extended, and this may be all that is needed to receive a good signal, especially if the signal is close.

  • Coaxial antennas can be unscrewed and pulled out a little. Sometimes, several additional antennas inside the unit can be extended to increase the FM reception significantly.
  • Single wire antennas can be extended by wrapping any kind of single wire around the end and then running the wire on curtain rods, along with the ceiling, or into the attic. Multiple tight loops on the antenna will increase the effectiveness.
  • Wire extensions can be run outside into trees and onto aluminum guttering to increase the antenna area.

Be aware that wiring that is run outside and connected to a plugged radio will act as a lightning rod because the radio is grounded. Do not use this setup in an area with frequent lightning storms, or when a storm is approaching.

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