Instructables

How to I make an AM Antenna?

I was recently given a "Tuner" set up ( one of those boxes that you plug TV, DVD, speakers, CD, and VCR, into and has a built in FM /AM tuners)

The Tuner has ports in the back to plug in wires for FM antenna and AM Antenna. ( 2 wire accepting ports per band )

How do I make antennas to plug in to the back of a radio tuner with just wires?

Do I need to put in other components?

What other components might I need, where do I find them, and how EXACTLY do I incorporate them?

I tried to follow the Instructable http://www.instructables.com/id/Medium_Wave_AM_broadcast_band_resonant_loop_antenn/

I ran the two wires into the back of the Tuner instead of a "polyvaricon" (plastic insulated variable tuning capacitor) because the Instructable, as it is written, does not provide for plugging the Antenna into anything.

I Used a 12ft length of CAT5 ethernet cable to create 8 loops of insulated wire as described in the Instructable but still can not get very good signal on local AM Stations that are less than 20 Miles away.

110100101105 years ago
way used in crystal radios - usually more efficient take 2 wires of length 1/4 the wavelength of your radio station connect each to 1 of the entries stretch in different directions if you want to place the antenna (often 10 - 20 M long) outdoors then stretch it there and go with a twisted pair of wires from the center of the antenna to the radio sometimes earth (tap / window frame / etc) can be used as substitute to 1 of the wires this way is not compact at all but powerfull enough to power entire small radios from the air - without any connection to electricity source or batteries way used in lots of modern radios - way more compact but less efficient make a loop of 5 - 7 turns isolated wire about 4 in (0.1 M) size make twisted pair from the 2 wires exiting and connect to radio
coretj (author)  110100101105 years ago
I'm not trying to broadcast... just pick up the AM Talk radio station(760).. and I've already built a loop that is 8 turns with a circumference of 12ft Do i need to make it smaller? It doesn't work that well.
all what i said is for receiving experiment with the exact size and direction of stuff etc another direction you may try is to reduce interference from other devices. for example unplug your computer when you experiment with the radio
coretj (author)  110100101105 years ago
I just don't understand how I can have the little antenna in my truck pick up the station just fine but I make something 50 times bigger and it doesn't work.
rsiglow coretj1 year ago
Your truck radio antenna is "loaded" by inductance to be electrically longer than it appears to be. It's much "longer" than it appears, and is a very efficient tuned antenna. You typically can't see the coil which produces this inductance. That's why if you ever break the antenna off, a coathanger ridgidly attached to the broken stub will often provide resonable reception (until the connection point rusts). The truck radio also has a very efficient counterpoise to the vertical antenna, the metal truck body. There is an additional comment about the quality of the car radio itself, which could also be true in your particular case.
quality of the radio itself. car radios are often better than home less interference. in the car you have very little electromagnetic noise. at home you have a lot maybe somthing else
rsiglow coretj1 year ago
Sorry for late response, just saw your post. Your antenna's aperture (12' loop) is probably too big. What you have constructed is more like a longwire, as opposed to the loop antenna I constructed. Try 50' of #30AWG insulated wire around a 24" (approx) picture frame if you want more gain. Oh, and don't use coax or a metal picture frame.
73's de W0AMB
rsiglow1 year ago
Cat5 ethernet cable is actually composed of a multiple number of parallel twisted pair wires. You may have introduced a lot of cancellation due the mutual coupling between the twisted pairs of wires within the jacket of the cable. What you really want to use is a SINGLE strand of at least 50' of insulated wire. This is how the loop antenna produces gain. I used #30AWG since it is small, and can easily be concealed, and taped to the back of any non-metal picture frame. If you want some gain on a loop antenna, in the AM broadcast band, see my other recent comment regarding the antenna's aperture (try it around a 2' square). Also note that this loop antenna will be bi-directional. You may have to rotate the "hole" of the antenna towards your desired station.
knoxarama4 years ago

so your trying to make an antennae that will plug into the socket on your radio? Just twist some tin foil into a rod and put in there. It only has to have one contact since the radio waves are basically static. Not static, but conduct like it. If this is what you were asking.

Radio waves are not "basically static". The "static" you hear on any modern (superheterodyne) AM radio is really the ABSENCE of a radio signal, and is actually produced from your own radio's (local oscillator) circuitry. If you are talking about hearing lightning on your AM radio, that is another case. Lightning produces broadband radio noise which a sensitive AM receiver often "mistakes" as a true radio signal. If you are talking about static electricity that is another form also. Static electricity often occurs when you walk across a carpet and build up a charge (like a capacitor), and then you discharge yourself to a metal surface. (Yes a nearby AM radio may even produce a slight "pop" when you do this). Think of radio waves being a highly controlled voltage which travels thru the air (aka "transmitted") instead of thru wires. This is a much better approximation than the term "static".
rsiglow3 years ago
This is so easy, I just had to share it. Someone recommended winding 50 ft of wire around a shoe box lid. I was about to try this, but I thought my wife would deem it "tacky", even on the garage wall. So I wound 50' of #30 AWG wire around an unused picture, and hung it high on the wall. This "stealth" antenna now pulls in KDKA(PGH) and WWL (New Orleans) @night time, into Minnesota ! Previously, the garage radio would only get 1 local AM channel w/o the antenna. What a difference, now it gets dozens.
That's an awesome idea! I wonder if it might work with a picture FRAME. If so, should it be plastic or metal, or even wood? I have a Panasonic SC-AK20 Stereo that's just dying for this advice! I'll still agree with the #30 AWG wire suggestion. Just so you have an idea of what I'm working with, there is an attached picture of my stereo, front view.
YES, use either wood or plastic picture frame like I did. Hook each end of the cable to one of the AM antenna posts on the back of your radio. (I think I may even have the same identical radio you have.) Remember the AM Loop Antenna you have just constructed works best from the front and back of the picture. The edges of the picture fame are null, so you may have to rotate your picture 90 degrees if your desired station(s) are in that direction. You'll be amazed how much better this antenna works compared to the little black loop that originally came w/the radio !
ajsims3 years ago
This is an old post but since I did not see a correct answer to the question I figured I would answer it.
Build the antenna exactly as per the instructable.
You will have to inductively couple your radio. You do this by creating a smaller loop that has a feed line to your radio. This smaller loop is placed in the center or near the antenna. A signal is then inductively coupled onto the smaller loop and runs to the back of your radio.
Make sure your smaller loop does not touch or short out to the antenna.

This is an example of what I am talking about.

http://www.mtmscientific.com/pickup.html
Dr.Bill4 years ago
OR ! take a 12"x 12" piece of cardboard find the exact center and hot glue the end of the wire down and wind in a circle so the wire touches the previous winding hot gluing all the way. A tight flat coil will result. I hung mine on a cabinet door because it was very directional. Most times only 1 end of the wire needs to be connected to the radio but if that does not work have the center end extended out the back of the coil to connect to the other connection.
Dr.Bill4 years ago
take 2 pieces of wood 2"x1/4"x3' long cut 1 in half cut notches down both edges of both sticks and wind the wire around catching it in each notch 1 time each on 1 side move to other side at top with the continuous wire continue winding from top around and around like the other side. When you get to the last notch glue the wire in place. If you want you can put an air variable to "tune the antenna" and what you will be doing there is removing the static sound you hear on the radio by nulling
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!