The Ultimate AM Radio Antenna
as realized by

When I searched on “AM radio antenna design”, the best result I found was How to Make the Ultimate AM Antenna by R. Wagoner. The design looked right, but only by making one could I find out how good it was. The result is audibly better AM reception at my home in Mesa, Arizona.

The original wooden frame was problematic to build (and alas, not very substantial) so I tried substituting plastic pipe for the wood, with the antenna wires on the inside. This proved to be durable and easy to construct.

Here are the parts ...

AM_parts

  1. 6' of telephone cable. Round telephone cable with four solid #22 wires works best. Cable with twisted pairs of wires interferes with AM reception, and therefore must be avoided.
    Thanks to Gary Camp for advising me about this.
  2. three 11" sections of 1/2" plastic pipe.
  3. three 5" sections of 1/2" plastic pipe.
  4. four slip elbows for 1/2" plastic pipe.
  5. one slip “T” for 1/2" plastic pipe.
  6. wire cutting and stripping tool
  7. radio and TV solder
  8. electrical tape

Here’s how to assemble the antenna:

1. Thread the telephone cable through the plastic pipes and fittings, like stringing beads. The ends of the cable coming out the bottom should be of approximately equal length. It’s easier to get them even if you start by threading the 11" plastic pipe on top. IMG_3371_530

2. Press the plastic pipes and fittings together, with the telephone cable inside. You can glue the plastic parts with PVC cement, but you don’t have to. They fit snugly. IMG_3372_530

3. Strip the outer insulation from both ends of the telephone cable.

If you don’t already have a wire cutting and stripping tool it’s well worth buying one. Mine is from JerryCo, part no. 40587.
IMG_3375_530

4. Cut all but the white wire on the left, and all but the black wire on the right, leaving just enough to connect the wires that remain. Save the pieces of wire you cut off. IMG_3380_530

5. Strip and solder each short wire on the left to a short wire on the right. Make sure each connection is from a left wire to a right wire. Remember that left and right wires of the same color are opposite ends of the same wire. An effective connection pattern is
left right
white — red
red — green
green — black

You are transforming the 4-conductor telephone cable into a loop with 4 turns of wire.
IMG_3386_530

6. Test the loop for circuit continuity at the ends of the two long wires you didn’t cut.

My home-made circuit continuity tester has both a beeper and a light that come on when the circuit is closed.
IMG_3389_530

7. Twist the two long wires together so that they have approximately 2 turns per inch.

If the wires aren’t too long you can hold the loose ends up with one hand while turning the antenna assembly below them. Watch out for kinking.
IMG_3394_530

8. If the resulting antenna leads aren’t long enough, extend them using the pieces of wire you cut off in step 4, all twisted so they have approximately 2 turns per inch. IMG_3395_530

9. Build a base for your antenna out of wood, plastic pipe, or other insulating material. Or, depending on the location, you could hang the antenna from a ceiling.

Here’s where I used that third 5" plastic pipe. Drill a hole in one side to let the wires through.
IMG_3399_530

IMG_3403_530
You can turn the antenna in any direction to get the best AM radio reception.



Ted,

This was fascinating and I have a few observations to share.

The verbal description was excellent, yet when I referred to the photographs there seemed to be disconnect when you said “Cut all but one of the wires on the left, and all but one of the wires on the right,” since when I referred to the photo I saw only one long wire. Turns out that the background color, the wire color, and my “first look” observation skills did not allow me to see the black wire. Fortunately I continued to follow the instructions to the end, then went back and read it again with the knowledge that there had to be two long wires, and walla there they were. Once the black wire is seen it is obvious in subsequent looks. Working in medical imaging, I am always fascinated by the way the human visual system filters image information, causing some things to be invisible until they are pointed out.

I am curious whether the shape and size of the loop is critical to the efficiency of the AM reception and how you determined the optimum design.

For those that don’t have any engineering or science background, it would help to show how the antenna is connected to the radio, perhaps even several different radios to demonstrate different means/locations of the connection.

You might also want to check out the broadcast Digital TV Antenna described in the attached document. You might also want to check out the broadcast Digital TV Antenna described in Makezine.

Loved your post. Thank you for sharing.

Phil Rauch



Phil,

Thanks! It’s great to hear from you.

The green carpet in my living room might not have been the best background. I’d thought about using a table, or the concrete floor on the patio, but wound up on my living room carpet.

The shape and size of the AM antenna are optimal, according to Wagoner. I don’t know enough about antenna design to say much more, so I adopted Carver’s design as given.

IMG_0580_530

On the back of my stereo receiver (and apparently most) there are antenna jacks marked for AM and FM. For best reception you should use both an AM antenna and an FM antenna, just by inserting the wires in their corresponding jacks.

The Digital TV Coat Hanger Antenna looks interesting. We didn’t throw away all of our metal coat hangers when my family switched to plastic.

Ted


  updated October 29, 2014 Mile 204 Ted Tenny