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What most people want is just to buy a radio and have it pick up the station they want. It's only tyros like us who will go to the trouble of owning a radio -and- an add-on antenna. Had a gentleman come into a TV shop I was working in, looking for an AM radio with really good reception, as his favorite station was at the very edge and sometimes disappeared. I looked at what he had and determined the only way he would get better reception was with an add-on antenna of some kind, loop or wire. I spent time and effort researching and buying parts for a tuned loop, specifically made to look like one of the early wood-framed ones. In the end he went out and bought some POS AM/FM table radio because it looked like an old radio, and went with his furniture. He couldn't pick up his radio station -at- -all- with it, but he kept it because it looked good with his decor. And he didn't buy the loop I was building for him, because he decided it wouldn't go with his furniture. People like us get satisfaction from hand-building something that then pulls in stations from very far away. I'm betting there are quite a few here who've even built their own radio from scratch. I'm also on the CrystalRadio list, and there are people there who even build their own tuning capacitors and galena crystals! Most people just want to hit a button and hear music or their favorite talk-radio station. So in the end I think most people would rather pay $20 or $50 more for a radio than have to buy and lug around even a $5 loop, no matter how easy to transport it may be. Steve --- Bruce Carter <brucec@...> wrote: ... > AM loops seem to be one of those products for which there would > be > demand if the AM band had less noise on it, better programming, > if > people were more educated about the product, and the product was > priced right. I think, for example, if you had a light weight, > portalbe / collapsible loop that was large enough to really make > a > difference, you could sell it if it was under $5 to people > relocated > from their "home team" city and they could DX their old 50 KW > sports > station. Much more $ than that, and people won't buy. __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/

Gents, Here's the link to a compact antenna that I think deserves more in the way of exploration and exploitation. <http://www.antennex.com/hws/ws0601/morebp.html> There's a bunch of other stuff in the Antennex site archives but you have to be a member to access it. Wish I could port some of it over here. Hmmm... maybe some non-infringing synopses as I have the time. This is the kind of thing I think would be an appropriate topic for this group in addition to our loopy stuff. 73, 'Bear' NH7SR

Here is another link to a site dealing with compact antennas including the coffee can antenna, cone disk, bicone and eh antennas. There are a number of useful Javascript calculators here as well. <http://www.qsl.net/w0kph> Check out the "What Can Small Antennas Do?" and "Per request - Pages from old Web Site" links on this site. The emphasis here is on ham radio and antennas that can be used for transmitting as well as receiving. The instructions for tuning with an impedance bridge can probably be ignored if the antenna is only to be used for receiving. Tuning "by ear" will probably work just as well. Much of the criticism regarding compact antennas such as these stems from the fact that they exhibit a loss compared to a full-size dipole or vertical. That is true... so do MagLoops. OTOH, they also have a reputation for lower noise in receiving applications. 73, 'Bear' NH7SR (On the prowl for more goodies)

Following up on a post in the VLF group this morning I visited Renato's VLF site at... <http://www.vlf.it> where he posted details of a new antenna he is using for VLF/ELF reception. <http://www.vlf.it/FSR/FSR.html> Although the antenna is designed for VLF/ELF it is quite possible that the same approach will work well for LF/MW and maybe even HF. As we say here in Hawaii... Try look! 73, 'Bear' NH7SR

Hello ! Question in the title... Can anybody give me some info about these antenas ? 73's Gilles FM5AD

I find it helps if you finish off the pizza first. The Q is increased quite a bit. ;') Steve --- qrpbear <qrpbear@...> wrote: > Scott, > > Oh.. ya gotta space 'em otherwise you'll have nowhere to wind the > > colored yarns to make it pretty <G> > > Spacing at least one wire diameter will improve efficiency and Q. > For > a Pizza Box Loop it probably doesn't matter all that much and the > difference may be un-noticeable. __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/

Now available at: http://www.ti.com/amplifier_utilities Then click on the "design calculator utilities", and the loop antenna calculator is at the bottom. The choice for "wire" is the one you want. Remember this is for wire with no spacing between turns, I will post a more general version on my site later ----

Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the loopantennas group. File : /SpiderWeaveCoils.txt Uploaded by : alienrelics <alienrelics@...> Description : The Basket Weave (Spider Weave) Loop Antenna Coils by RHF. With links for other parts necessary for loop ant. and crystal radio construction. You can access this file at the URL http://groups.yahoo.com/group/loopantennas/files/SpiderWeaveCoils.txt To learn more about file sharing for your group, please visit http://help.yahoo.com/help/us/groups/files Regards, alienrelics <alienrelics@...>

Hello All: I noticed that I wasn't getting any email from the various groups I belong to, and checked Yahoo groups and each of then said my mail was bouncing, so I went through their reactivation process and when I went back to the Yahoo groups, there was no warning message. Yet, I have not received any messages in the last hour or so. Could anyone send a "testing" message to the group so I can see if my reactivation worked? Thanks, Barry

Hello All: For some time now, I have been wondering about the electromagnetic properties of common materials, and find these things rather hard to discover. The few times I have asked about them on different electronics-oriented groups, most people have dismissed them as not workable. I don't want to get too off-topic, but I hope some of you can point me in a productive direction. I also wanted to ask some rather nieve questions that I hope someone can either answer or point me in the right direction. So, here goes. QUESTIONS: 1. Would it be possible to make a VLF loop-stick out of rebar? First thing I can think of is that the remnance of rebar would be a problem, but nowhere have I been able to find the magnetic properties of such a readily available and cheap material. What about its permeability, its coercivity? What does its B/H curve look like? 2. If a "square" coil is considered optimal, why is an air-core loop antenna so far out of square? I know aperture is an issue here, but what are the trade-offs in terms of Q and lack of symmetry between diameter and coil-depth? BTW, some ham in the state of Washington (don't have the link offhand, but I can look it up if anyone is interested) has a spreadsheet called "professor Coyle" that is very good for modeling coils (both solenoid and spiderweb). I have modified it to include wire resistance tables and a few other bells and whistles. HARE BRAINED IDEAS: 1. What if you built a "steerable null" antenna using two identical loop antennas at the end of a rotatable beam, and, in turn (heh) each of the loops were also rotatable? Something Bear said awhile back triggered this idea off, and I remembered experimenting with a crystal set from Gollum's Crystal Radio site that used two spider-web coils, one for the antenna and one for the crystal detector. The coils were coupled (face to face) at a distance of about 6-inches, but I could get very responsive results even at a distance of 12-inches apart, so I played around with rotating one with respect to another and found the nulling very sharp. I haven't done any measurement of this arrangement, so this is only an intuitive observation. BTW, I also built a "box" loop using a wooden "in-basket" I got at a Michaels craft store, and used the ears of the in-box to mount it on a base (also from Michaels) so it became an altazimuth loop. It works very well with my little Radio Shack DX-370 at a distance of about 6-inches. The bottom of the in-box is used as the face of the loop, the edge of the box is where the coil is wound, and a little poly variable cap is mounted at the center of the "bottom" of the in-box. 2. Is a helical considered a loop? What if you built a large helical antenna and treated it as if it were a loop antenna? I mean, a helical is just a streached-out loop, isn't it? The only difference I can see is that the distributed capacitance drops and so does the inter-winding inductance. Humm, what am I missing here? 3. A few times on this list someone has mentioned mobius-strip loops; what is the theory behind them and how well do they work? What are their properties in a vertical and horizontal plane of orientation? (oops, that was a question, not a HBI) Well, that's all for now. Later, Barry

Bear, I tried to answer you on the GCC Loop Group. For some reason the post didn't appear. So: Bear, My shoggoth upchucked allowing me to provide the following example: An impedance analyzer gives an impedance of 3 + j215 ohms at 1.6 MHz for a certain Pioneer AM loop. Let's make the proximal capacitor (Cp) 7900 pF and the distal capacitor (Cd) 490 pF. That gives capacitive reactances –j12.6 ohms and –j203 ohms respectively at 1.6 MHz. The loop in series with Cd gives 3 + j215 – j203 = 3 + j12 Using the parallel impedance formula gives (0 – j12.6)(3 + j12)/[ (0 – j12.6)+(3 + j12)] = 50.9 – j2.4 ohms That's not too bad for the shoggoth and me making some wild guesses. Cp could be a 5100 pF cap with a dip switch to add 200, 400, 800, 1600, and 3300 pF in parallel. Cd could be a 360 pF variable with 200 pF in parallel. Actually the shoggoth used http://www.circuitsage.com/matching/matcher2.html and transformed the negative inductor in the upper right network into a capacitor. Regards, Steven

All, Can't post the Rod Newkirk, W9BRD, article on distributed capacitance multiturn loops but I did find a web site with pics, diagrams and info for a 7 mHz version at... <http://www.natradioco.com/rdey/ant40m.htm> Also ran across another site featuring an article about a 12" diameter 5-30 MHz loop with a rather unique coupling method that I hadn't seen before. You'll find that one at... <http://www.carc.org.uk/html/archive16.html> It's entitled "Fun and Games with the G3LZH Miniature Loop Antenna." Enjoy and 73, 'Bear' NH7SR

Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the loopantennas group. File : /capcalc.exe Uploaded by : qrpbear <qrpbear@...> Description : KI6GD's Capacitance Calculator for making your own capacitors. You can access this file at the URL http://groups.yahoo.com/group/loopantennas/files/capcalc.exe To learn more about file sharing for your group, please visit http://help.yahoo.com/help/us/groups/files Regards, qrpbear <qrpbear@...>

This has indeed become a very good day. No sooner did I ask for a cap calculator, then one appears in the files section. Thank you very much! So many great links, so many interesting posts...think I'm gonna like it here. Thanks again, Karl

I own four loops, the first two were the Radio Shack loops, which is/are a fine product. *BUT* - I wanted more because I knew I could get more out of a loop antenna. My second passion (very close) to SW listening is BCB dxing. I have what I feel two great BCB dx setups. They both include the GE P-780, if you aren't familiar with this 'just BCB' dx radio here is the link, follow the other links with this to read all about it. http://www.transistor.org/collection/ge/ge14.html It 'truly' is an amazing BCB radio and they are built like a battleship and I own a lot of radios and I finally found the perfect setup for me. This radio (which is key) is that it is both sensitive and selective. I've sat my first radio ( I own two of these beauties) on my lazy susan turntable and on the back of that table is what I call my 'Black Beauty.' It is a 30x30 (painted black) PVC loop http://web.wt.net/~nm5k/loop5.jpg it is a Diamond Loop or some call a 'pancake Loop' with a variable cap that is a six section-830pF that tunes from 530-1830. It is literally mounted to the back of my table and has a very big what I call 'capture zone.' This loop, because it is PVC, can be tilted forward (which is great) leaned backwards turned to either side, I can even spin it around upside down if I wanted. It is really an excellent setup for DXing and blows away when I had 500ft. of wire hooked to it. I had so many signals coming from everywhere at one time, it was too much. This loop has totally eliminated that problem and I can't be happier, I wished I could take a pic and post it but I don't have a camera and I wouldn't know how to send it. But my table I wouldn't sell for a grand, this setup has added MANY qsl's. I highly recommend both the radio and that loop, if you can make it bigger- even better. In my living room, I have a real nice old varnished/stained sewing machine stand, of course minus the sewing machine. It look just like a table till you open up the top and the lid entends out, it is on rollers On that I have another GE P-780 along with another loop, this one costs me some money, it was made out of wood and stained and has spokes and beautiful red litz wire was used. It was originally tuned from like 670 but I let Dave know I use the entire BCB and he added a small toggle switch and badda bing I have the entire BCB. Here is the link, scroll down to the 'Penta-Loop'.....the pic just doesn't do it justice. It truly is a piece of work............ http://www.schmarder.com/radios/misc-stuff/loops2.htm Dave takes pride in his radios and his loops and it shows, both in looks and in how it works. So that is my story and my loops, I love the 'Black Beauty' though, isn't that crazy, the PVC over the wooden/stained.... but both work great, it's just I spend more time in this room. Thanks, Gregg Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger

Hi All! New to the group, but not to radio. When I was a kid (very long ago), we used to make our own variable capacitors. Basically, we'd take a square of wood, varnish it well, and mount a square or disc of aluminum in the center, and attach a lead to it. This became the stator. A piece of celluloid (later plastic) was glued over this stator plate, and a similar piece of aluminum with a lead attached and a piece of phenolic rod glued in it's center, was placed on top to become the rotor. Both leads were attached to the board by fanstock clips. By manipulating (sliding) the rotor plate across the stator plate, you could go from full mesh to wide open. A friend of mine and fellow Boy Scout even took india ink and marked the receive locations of his favorite stations on the celluloid, making essentially, a rudimentary dial. Now, why am I bringing this all up (other than to wallow in nostalgia)? It seems to me that variable capacitors are becoming hard to find these days, and when you can find them they're pricy, and usually have to be combined with other items to make a "minimum purchase". Not good for a geezer like me, living on a fixed income. Does anybody have any experience homebrewing VCs? If so, maybe you could share some data or formulae for scaling the plates. Well, talk with you all again soon, Karl

Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the loopantennas group. File : /The Bear Cave/An Introduction to the Mysteries of Ground Radio.txt Uploaded by : qrpbear <qrpbear@...> Description : Do Geomantic antennas exist? Do they work? This article documents some of the discoveries made by early telegraph/telephone pioneers. You can access this file at the URL http://groups.yahoo.com/group/loopantennas/files/The%20Bear%20Cave/An%20Introduction%20to%20the%20Mysteries%20of%20Ground%20Radio.txt To learn more about file sharing for your group, please visit http://help.yahoo.com/help/us/groups/files Regards, qrpbear <qrpbear@...>

No... they ain't loops but they do offer some interesting potential that seems worthy of exploration. Especially for ground dwelling folk like me that have limited area for antenna farming. They are stealth antennas by nature. I have uploaded two text files regarding them to the "Bear Cave" in the Files area. 73, 'Bear' NH7SR (Now where's my pick'n'shovel? Got a bit of "gardening" to do <G>)

There's another compact antenna with its own new group here on Yahoo at... <http://groups.yahoo.com/group/flowerpot-antenna> There isn't much there yet but a few pictures and a link to the owner's home page. The antenna he describes is a form of ground independent coaxial monopole helically wound on a plastic flowerpot. It is tuneable by adding a variable capacitor across the far end of the antenna. There is a photo illustrating it. Throw an arrangement of plastic flowers in the pot and you have a nice attractive and very stealthy antenna. Now who could possibly object to something like that on 12th floor veranda in a condo? 73, 'Bear' NH7SR

We're up to 55 members! And lots of activity. Remember, if you have not posted yet, all new members are moderated. So don't be alarmed if your first message takes a few hours or a day to appear. I get on fairly often to check, subject to Real Life(tm). Once you've posted, I'll set you unmoderated. Just my way of quietly blocking spammers. Steve Greenfield, moderator of the new loopantennas