Introduction: A Dynamite Antenna for an AM Radio

Picture of A Dynamite Antenna for an AM Radio

I am probably not the only person who listens to AM radio, so this might come in handy for somebody else.

Back in the day, radios were AM only, and if you wanted to listen to your favorite programs you had to have an outside antenna. With the advent of the transistor radio, there soon ceased to be any way for you to connect your radio to an antenna. Most of the time, admittedly, the internal antenna worked well enough anyway. But not for everybody.

Step 1: Weakest Is Best

Picture of Weakest Is Best

If I am left alone with an AM radio, the first thing I usually do is tune around the band until I find the weakest station there is, then I listen to see where it is coming from. But without an external antenna, the station isn't usually all that far away.

But even if I put up an outside antenna, what good is it without a way to connect it to the radio?

Well, this antenna doesn't have to connect to the radio.

I know that sounds too good to be true, but it is true. The signal, gathered by the long wire antenna is inductively coupled to the radio's internal ferrite antenna.

Step 2:

Picture of

There are three parts to this antenna system, and if you are an adept scrounger, it won't cost you anything. If not, five bucks ought to do it.

First, as in the old days, you need a long wire antenna. You can go to a lot of trouble or not - it's up to you. The hard way is to buy bare antenna wire with a couple of insulators for either end and mount that. The easy way is to buy (or otherwise locate) a length of insulated wire. (Radio signals don't care if the wire is insulated or not.) Fifty feet would be oodles. The wire doesn't have to be very large in diameter. An ideal size would be a piece of either doorbell or telephone wire - just one conductor. It is very small in diameter but pretty strong.

The first thing you do is to connect one end of the wire (strip the insulation off) to some type of ground. The center screw of an electrical receptacle (or one of the screws on a light switch) would work fine. Run the wire to where you want your radio to be situated and make a coil of six turns, about the diameter of a saucer. Tape it to the wall, or to a piece of cardboard propped against the wall. Take the rest of the wire and run it out the window and tie it to something (keep it high enough not to strangle somebody who walks by) or else tie a fishing sinker or big hex nut on the end and chunk it up a tree.

Turn your radio on, select 'AM' and set it near the coil. You may have to twist and turn the radio, and move it closer or farther away, but stations that were weak and scratchy will leap out at you.

The first time I made one of these antenna systems, I added a small switch in series with the ground connection. Switched off, and a station was barely audible. Switched on, and I had to turn the volume down.

When I was in college, I worked in a retail electronics store. It was situated in a steel building and radio reception inside was non-existent. I rigged up one of these antennas, making a loop under the glass counter top. The difference was remarkable; all we had to do was hold the radio near the counter and signals would jump out of the speaker.

Be careful not to bring the wire or yourself anywhere near overhead electric lines, and if you live in an area prone to thunderstorms, either taking the antenna down when not in use or providing a really good ground and a knife switch to switch between it and the radio coil would be an important modification.

Try it out.

Comments

RobertoC134 (author)2016-08-16

A modification which works really well if you live in a rural area: Use any single strand wire-bell wire is fine. Start with a 50 turn coil-diameter doesn't matter. One end connected to a good earth ground, the other to a 100' long wire antenna. This will bring in many DX stations even during the daytime. The only caveat-any interference will also be amplified.

ROG2000 (author)2016-08-13

I am looking to modify this for an AM transmitter. Would there be anything different that I need to do that would be beneficial? (looking to use 803' of insulated copper wire) I'm not sure if I want to make a patch or a tube... or neither...

mhz-radio (author)2015-11-19

I've used a tunable loop antenna for AM and have listened to AM broadcast stations across the country. I live in Florida and can routinly receive Boston, Chicago and New York at night. I will post an Instructable on how to build an AM tunable loop antenna.

snoop911 (author)2015-06-27

There's an am radio station that I sometimes pickup (badly) late at night. I think I know where it is.. is it possible it's picking up a station 150 miles away?! I found some pictures of the construction in case it helps:

http://news.ccrane.com/2014/07/31/how-to-make-a-si...

http://www.mile204.us/PotsdamDan/RubeGoldberg/Ulti...

RangerJ (author)snoop9112015-09-14

oh, yeah, am travels a long way. You can browse for the call sign or town if you want to ID it.

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