Have you ever made an AM antenna?

**surreal** · February 24th, 2004, 10:28 AM

I want to make one but have no idea where to start.
I've looked at web pages, but just when I see something interesting they start putting those silly electronic symbols
in and talking about things I don't know yet.

Like what in the heck is a picofarads

Has anyone made one? Can you help me make one?

I mean how hard can it be? The little thing that comes with your stereo is too weak.

I'm too far out of the city to pick up an AM signal. (I need to make another FM antenna too)

**ablang** · February 24th, 2004, 11:05 AM

I remember my Communications professor made his own AM radio using some electronics parts. It was very simple in design. I wished I remember some more about it.

A farad is some unit of measurement. I forget what it stands for, or what it represents, but a pico is, I think a 10 to the minus 9 power of something.

**surreal** · February 24th, 2004, 11:19 AM

Well, thanks for the info ablang!

We seem to have about the same level of working knowledge

**RADAR1797** · February 24th, 2004, 11:30 AM

Well this what farads are:

The unit of capacitance is a farad. A 1-farad capacitor can store one coulomb (coo-lomb) of charge at 1 volt. A coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons. One amp represents a rate of electron flow of 1 coulomb of electrons per second, so a 1-farad capacitor can hold 1 amp-second of electrons at 1 volt.

-RADAR

**Theophylact** · February 24th, 2004, 11:31 AM

The farad is the unit of capacitance. A picofarad (pF) is ten-to-the-minus-twelfth farads.

The farad is an extremely large unit of capacitance. In practice, capacitors with values this large are almost never seen.

(Named after Michael Faraday.)

**wju425** · February 24th, 2004, 12:14 PM

I think Radio Shack has an FM antenna (maybe AM too) that you put on top of house (like a tv antenna). They may have a model that has an amplifier built in to pull in weak signals.

\o/ Billy

**Theophylact** · February 24th, 2004, 12:22 PM

I use the Terk Pi, myself.

**RADAR1797** · February 24th, 2004, 12:31 PM

Theo,

Do you pick 630 WMAL?

-RADAR

**surreal** · February 24th, 2004, 12:36 PM

Has anyone ever made their own AM antenna?

As in cheap or free out of stuff nerds have in the basement?

**Pexster** · February 24th, 2004, 12:39 PM

There are two basic ways to go for an AM broadcast band antenna --

1) A longwire, or dipole antenna

2) A directional loop

The longwire will receive signals the strongest where they come broadside to the antenna, so if you want a station to the North of you, run the wire East-to-West.

The directional loop will be much more directional (as the name implies). You can build this on a wood frame about 2-3 feet square. I'll try to find a plan for this.

The 1st option requires a lot of space, preferably out in your yard, but attic is better than nothing. The 2nd option is more work, but can give you some good "nulls" useful for canceling out interfering signals.

What kind of receiver do you have, and what antenna connections are on the back? One or two terminals?

**thekingofpain** · February 24th, 2004, 12:41 PM

Stuff a coathanger in it---ive seen that as a very popular accessory on some cars here :-)
You must have seen this during your search, right?:
http://members.cox.net/rwagoner/columns/am_antenna.html
Seems simple no high-tech terms...

**Theophylact** · February 24th, 2004, 12:45 PM

Originally posted by RADAR1797
Theo,

Do you pick 630 WMAL?

-RADAR

You know me better than that. WAMU (88.5 FM) and WETA (90.9) are more my cup of tea...

**Pexster** · February 24th, 2004, 12:47 PM

Here are a few links --

http://www.mindspring.com/~brucec/loop2.htm

http://www.vk2zay.net/am-loop.html

http://www.dxing.com/amband.htm

**whitebeard21** · February 24th, 2004, 12:47 PM

Go to radioshack and buy a roll of 22 gauge copper wire uninsulated is fine run it outside and at 90 degrees to the direction you want to recieve from, string it like a clothes line. If you don't have a screw on the back that says antenna but do have a whip or extendable you can wrap the wire around there. make sure you remove the varnish from the wire by scraming it with a knife or sanding it with sandpaper. If you have two screws for the antena one will say ground the other one is the one to use. The ground symbol looks like an upsidedown pine tree. it will improve reception if you run a wire from the ground lug to a metal waterpipe. This will also work for fm.
I am not going into how to tune the length it isn't important to you. there may be a screw that says tuning on the chasis if there is tune to a weak station near 640 and turn the volume down to barely audible them turn the screw for maximum volume. you can use finishing nails to string the wire with just take a wrap around the nail and proceede to the next.

I have tried to put this in beginners terms if you need something else explained just ask.

**RADAR1797** · February 24th, 2004, 02:00 PM

Theo,

Of course, I just want to know technical capability. I am having a hard time pulling in AM in my apartment.

-RADAR

**Solid Snake** · February 24th, 2004, 02:15 PM

A long straight wire will make a good antenna. It's best to run it perpendicular to the ground (vertically) to pick up stations from all directions. When I build amplifiers, they sometimes double as AM radios when I use unshielded wire, this is not good.

**phenious** · February 24th, 2004, 03:26 PM

Goto a toy store, most of them have build it your self radios for kids to play with, that should get you started in the right direction

-: phenious :-

**Uncle Bob** · February 24th, 2004, 04:02 PM

Originally posted by surreal
I want to make one but have no idea where to start.
I've looked at web pages, but just when I see something interesting they start putting those silly electronic symbols
in and talking about things I don't know yet.
Like what in the heck is a picofarads

Has anyone made one? Can you help me make one?

I mean how hard can it be? The little thing that comes with your stereo is too weak.

I'm too far out of the city to pick up an AM signal. (I need to make another FM antenna too)

Yes. I made a simple antenna for a CB radio. It was what's called a folded dipole. Two wires that totaled 11m in length attached to the roof of the house. Surprised me. It actually worked.

**surreal** · February 24th, 2004, 05:07 PM

Originally posted by Pexster
One or two terminals?

2.
Thanks for the links. I'll see if they are anymore readable than the ones I found

**whitebeard21** · February 24th, 2004, 05:10 PM

Uncle bob If you use coax to connect it and place it in a vertical plane with ground wires 11 meters long radiating out every 15 degrees just under the soil and tied to the water table at the center you will have one of the best antenas going.
Use # 4 wire up and 16 for the grounds. Good for 1000 watts I have been told, of course I would never exceed the 5 watts for a cb license.