Have you ever wanted to use radio static noise for your next production? You know, that spacy noise only head in between radio stations, the kind of noise that suggests distant far away places or dreamy scenes that are only conjured up inside of our infinite imagination. Those ethereal static pops and scratches can be yours if you follow through these steps in building a "Space Noise Collector" or better known as a "Loop Antenna" If your like me and will just do about anything to hear these strange sounds from the ether and not mention for years I've been hunting down, trying my best to capture the sounds from one of the worlds oldest operational radio station. SAQ is a special historic radio station from Sweden that only transmits on the frequency of 17.2 Kc (that's kilocycles or kHz). A few times a year, it's behemoth 200,000 watt transmitter turns on to spew out it's audio frequency signal. Thats right, audio. 17.2 kc is in the range of human hearing and it's signal reaches out all over the world. To hear this station that screams or any other weird cosmic noises, requires the use of a special antenna. Build this Very Low Frequency (V.L.F.) loop antenna to experience radio sounds of the audio band. The VLF radio spectrum.
The following article is a step by step tutorial on how to construct a Very Low Frequency (V.L.F.) Loop Antenna. All material required for construction was obtained at a big retail hardware store (Lowes Hardware) Cost of this project was $50.
Before we begin this project it is imperative to understand why, what, and how a loop antenna works.
What? A loop antenna is a device to capture radio frequencies that are in the low frequency bands, basically any stations below say....2 mHz. If you can picture a big coils of wire. Ever done that high school science experiment where you wind wire around a big nail.....You Nailed It! That's a coil and that's what a loop antenna is. A big coil.
Why? Low frequencies require big long antennas in order to propagate through the air. To receive low frequencies you need the same long antenna to here it properly. How long? Well SAQ ( that Swedish station) I want to hear is on the frequency of 17.2 kc (kHz). The length of antenna for this station will be in the order of 17,441 meters. That's 73 miles long ! You can see that 73 miles is out of the question but "never fear, (As Bill Nye the Science Guy used to say before he raised to super stardom on Dancing With The Stars) science is hear". We can fake our way ( like on a drug test). By winding a big coil we can build up "inductance" (that's the stuff coils are made of) to fool the radio waves into thinking that we are using a full size antenna. "Science !"O.K. Bill that's enough, go back to dancing with the stars.
How ? A full size 73 mile antenna ( that's outrageous !) acts like a "tuned circuit " or it resonates on that frequency naturally. A loop antenna on the other hand is not a "tuned circuit" until this important component is connected across it. A capacitor is a series of metal plates that are sandwich together. It is connected to the loop antenna to resonate it at that frequency
O.K. so we all now understand what, why, and how a loop antenna works. We can now get started on building our "Loop Antenna" or our "Space Noise Collector" (what ever you want to call it. It's all good Bro.)
First step in making our "Space Noise Collector" (yea, that sounds way cooler) we need to build a frame to hold the coils in place. We'll use our old friend P.V.C piping (Plastic with Various Connectors) Ehh...ok fine "polyvinyl chloride". Obtain 3 "T" connectors and 2 cross connectors plus a 8 foot length of PVC pipe. Cut four 22" lengths of pipe and eight 4" sections. Oh, your probley wondering what size PVC pipe I use. 3/4 inch scheduled 8 pipe will be stiff enough to withstand the pressure of 150 windings. Using slandered PVC bonding, glue in place like so making a big cross:
I'm sure all of you woman out there have noticed my thick, full, long untamed hair. That's why I bought four combs. Ahh..OK... I'll get to the reason why I confused that gorgeous lady behind the counter at the drug store as to why this nerdy looking guy with almost no hair needed four combs.
After extensive and exhaustive complex number crunching, I came up with the right amount the turns for this loop antenna to resonate down low.....Way down low in frequency, 17 Kc (kHz) to be exact ( that's outrageous !). The magic number is 150 turns of 24 AWG wire. So that comes out to ( Ehh... I never was good at basic math) Pi = 3.14 x 48 inch = 150.7 inch (that's the circumference). 150.7 / 12 = 12.5 feet. So 12.5 x150 turns = 1884 feet of 24 AWG wire. Wow, everything down low is big. Are you big down low ??? Ha Ha!
Fortunately I'm a man and I keep things around no matter how useless it is. A spool of 24 AWG wire was constantly falling off of the work bench onto my feet, so I took the spools of wire and did the next best thing a man could do with something that harts him (Shove it into a deep dark corner where no one can find it when you need it) FOUND IT!
OK now can we wind? Eh, maybe YOU can but I want a nice manicured looking loop. A pretty loop is a happy loop. Now the combs you've been wondering about. Using the combs as a spacer for the windings on the loop, we attach them to the frame like so.
After having our day of beauty, we start winding. I used dowel rods through a hole drilled in the center of our loop to support it while spinning it around and around (don't forget to count your turns !)
When winding, be sure to feed the wire through each and every single tooth of all four combs. Theirs about 120 teeth so you might have to over lap a few windings in order to get to the magical number of 150 turns.
To make it easier for you to see what is happening; here's one of my world famous Windows 3.1 draw pad images (we're high tech at Ionosonde Recordings)
The ends of the big winding (150 turns) connects directly to the capacitor and the "smaller winding " (10 turns) connects to the audio input socket of your sound card.
The capacitor value was calculated to be around 1500 pF. Again, as a man I collect stuff. So I had on hand, a 2000 pF variable capacitor. Now I know it's hard to come across one that size. A simple trick you can perform is to buy one of these capacitors from the Crystalset Society Their only 350 pF but if you connect a .001 disk ceramic cap across, it will get you up to the desired capacitance value of 1500pF.
The loop is done and all we need to do is connect it to our sound card. If you like, you can listen to the wide band noise that comes out of this antenna with your favorite audio editor program just don't forget to crank up the microphone gain all the way up. Or if you really want to explore the VLF band, then your going to want to get something called an SDR (software based receiver). What this program does is turn you computer into a high performance radio. There's a realy slick, easy to use free VLF receiver program you can use to listen to. Download it for free here .
To operate this antenna properly, slowly turn the shaft of the tuning capacitor until the volume of the noise level peaks. When the noise is at it's loudest, the antenna is at resonates at the frequency your listening to. Now the best part about this antenna is it's directional properties. When you rotate it on it's vertical axis - you will notice the noise and signals will vary in intensity and will also sharply disappear.
Have fun with your "Space Noise Collector".