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Stealth Loop antenna
This is an interesting antenna. It is a mobile stealth magnetic loop
antenna. http://stealth.ae/plugins/custompage...categories=136 I watched the video and checked out the details. The antenna is basically a loop with the roof of the car (the bottom of the luggage rack) as the ground side of the loop, the antenna goes up, folds over the top and back down to the other side of the roof where it feeds thru a high voltage vacuum variable capacitor back to ground. --------------------------- | | |_ | | |( coax conx) = Capacitor | -|_____________| ^ (roof) ^ (feed) I am not as good an artist as some of you, but here is my graphic The coax feeds with a gamma? and is tuned by a stepper motor tuning the vacuum variable cap. Depending on which of the three models, it operates from 1.5-10 MHz, 2.7-15.5 MHz, or 4.5-22 MHz at up to 150 watts. The technical notes have more interesting details: http://stealth.ae/plugins/custompage...cles.php?id=10 It seems to me a homebrew version could be made for base use such as for those in restricted homes. Placed on the peak of the house, the ground side could be a wire across the top of the peak and the loop lift up during use so it would not attract too much attention to the neighbors. I wonder what the size and cost of the Vacuum variable is to make a similar antenna?? Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
Stealth Loop antenna
On Thu, 20 Mar 2008 09:30:34 -0400, Buck
wrote: I wonder what the size and cost of the Vacuum variable is to make a similar antenna?? Hi Buck, Take your cue from the page. Multiply by Q and you have your ratings (add a safety factor). Go to eBay and look at the prices. Place order and wait for the mail. Assemble. Operate. I suspect you already know that and are seeking solutions that border on fantasy. Art has revealed the characteristics of his 160M antenna (it takes only scaling to your favorite band) to obtain remarkable results (he knows what they are, but hasn't actually tested one). Fantasy publication is common enough here to satisfy any taste: You can get at least 3dB more "efficiency" (emphasis due to its new, tailored definition). You enjoy new equilibriums not formerly available in common and ordinary antennas (such as those drab and outdated models found at the web page you provided). You can discover added signal strength from Gaussian principles (it's not just about gain anymore). Find the hidden power of polarization unknown to the general antenna marketplace. Size is of no consequence with counterwound coupling. Q is no longer the irritating limitation it once was. Marvel at hiding it in a hula hoop in the grass so the neighbors don't suspect it as an antenna. No RFI either! Mount it on a steerable camera mount so you can point it (and the camera) into neighbor's windows. Advantages galore to be found that were previously unthinkable with those huge and cumbersome antennas that could only communicate with half the world. 73's Richard Clark, KB7QHC |
Stealth Loop antenna
On 20-Mar-2008, Buck wrote: Path: border1.nntp.dca.giganews.com!border2.nntp.dca.gig anews.com!nntp.giganews.com!bigfeed3.bellsouth.net !bigfeed.bellsouth.net!bignumber.bellsouth.net!new s.bellsouth.net!bignews7.bellsouth.net.POSTED!b6d4 19e3!not-for-mail From: Buck Newsgroups: rec.radio.amateur.antenna Subject: Stealth Loop antenna Message-ID: X-Newsreader: Forte Agent 1.93/32.576 English (American) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 48 X-Complaints-To: X-Abuse-Info: Please forward a copy of all headers for proper handling X-Trace: enggpaojkliedbjjdbdpiflmbcekedmfhojhikkbagflhcbopd pcindpodohfflilmehcadebpjbmnbeonldlemekfihcohpppai mpifmkcegckdogcmapfnfkkinfaikccgicoleplfnlbfebeelh cnmdabofba NNTP-Posting-Date: Thu, 20 Mar 2008 09:30:13 EDT Organization: BellSouth Internet Group Date: Thu, 20 Mar 2008 09:30:34 -0400 Bytes: 2671 X-Original-Bytes: 2628 Xref: number1.nntp.dca.giganews.com rec.radio.amateur.antenna:295507 This is an interesting antenna. It is a mobile stealth magnetic loop antenna. http://stealth.ae/plugins/custompage...categories=136 I watched the video and checked out the details. The antenna is basically a loop with the roof of the car (the bottom of the luggage rack) as the ground side of the loop, the antenna goes up, folds over the top and back down to the other side of the roof where it feeds thru a high voltage vacuum variable capacitor back to ground. --------------------------- | | |_ | | |( coax conx) = Capacitor | -|_____________| ^ (roof) ^ (feed) I am not as good an artist as some of you, but here is my graphic The coax feeds with a gamma? and is tuned by a stepper motor tuning the vacuum variable cap. Depending on which of the three models, it operates from 1.5-10 MHz, 2.7-15.5 MHz, or 4.5-22 MHz at up to 150 watts. The technical notes have more interesting details: http://stealth.ae/plugins/custompage...cles.php?id=10 It seems to me a homebrew version could be made for base use such as for those in restricted homes. Placed on the peak of the house, the ground side could be a wire across the top of the peak and the loop lift up during use so it would not attract too much attention to the neighbors. I wonder what the size and cost of the Vacuum variable is to make a similar antenna?? Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." Look up DDRR Antenna at ARRL. It works as a very short top-loaded vertical resonated with a capacitor. Ken Fowler, KO6NO |
Stealth Loop antenna
"Ken Fowler" wrote in message . .. On 20-Mar-2008, Buck wrote: Path: border1.nntp.dca.giganews.com!border2.nntp.dca.gig anews.com!nntp.giganews.com!bigfeed3.bellsouth.net !bigfeed.bellsouth.net!bignumber.bellsouth.net!new s.bellsouth.net!bignews7.bellsouth.net.POSTED!b6d4 19e3!not-for-mail From: Buck Newsgroups: rec.radio.amateur.antenna Subject: Stealth Loop antenna Message-ID: X-Newsreader: Forte Agent 1.93/32.576 English (American) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 48 X-Complaints-To: X-Abuse-Info: Please forward a copy of all headers for proper handling X-Trace: enggpaojkliedbjjdbdpiflmbcekedmfhojhikkbagflhcbopd pcindpodohfflilmehcadebpjbmnbeonldlemekfihcohpppai mpifmkcegckdogcmapfnfkkinfaikccgicoleplfnlbfebeelh cnmdabofba NNTP-Posting-Date: Thu, 20 Mar 2008 09:30:13 EDT Organization: BellSouth Internet Group Date: Thu, 20 Mar 2008 09:30:34 -0400 Bytes: 2671 X-Original-Bytes: 2628 Xref: number1.nntp.dca.giganews.com rec.radio.amateur.antenna:295507 This is an interesting antenna. It is a mobile stealth magnetic loop antenna. http://stealth.ae/plugins/custompage...categories=136 I watched the video and checked out the details. The antenna is basically a loop with the roof of the car (the bottom of the luggage rack) as the ground side of the loop, the antenna goes up, folds over the top and back down to the other side of the roof where it feeds thru a high voltage vacuum variable capacitor back to ground. --------------------------- | | |_ | | |( coax conx) = Capacitor | -|_____________| ^ (roof) ^ (feed) I am not as good an artist as some of you, but here is my graphic The coax feeds with a gamma? and is tuned by a stepper motor tuning the vacuum variable cap. Depending on which of the three models, it operates from 1.5-10 MHz, 2.7-15.5 MHz, or 4.5-22 MHz at up to 150 watts. The technical notes have more interesting details: http://stealth.ae/plugins/custompage...cles.php?id=10 It seems to me a homebrew version could be made for base use such as for those in restricted homes. Placed on the peak of the house, the ground side could be a wire across the top of the peak and the loop lift up during use so it would not attract too much attention to the neighbors. I wonder what the size and cost of the Vacuum variable is to make a similar antenna?? Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." Look up DDRR Antenna at ARRL. It works as a very short top-loaded vertical resonated with a capacitor. Ken Fowler, KO6NO Yep, back in the stone age, Collins Radio put one of those on top of Lyndon Johnson's election campaign train. |
Stealth Loop antenna
Buck wrote:
This is an interesting antenna. It is a mobile stealth magnetic loop antenna. http://stealth.ae/plugins/custompage...categories=136 I watched the video and checked out the details. The antenna is basically a loop with the roof of the car (the bottom of the luggage rack) as the ground side of the loop, the antenna goes up, folds over the top and back down to the other side of the roof where it feeds thru a high voltage vacuum variable capacitor back to ground. Isn't this like the Q-Mac antenna sold in Australia? http://www.qmac.com/mobile_antennas.html --------------------------- | | |_ | | |( coax conx) = Capacitor | -|_____________| ^ (roof) ^ (feed) I am not as good an artist as some of you, but here is my graphic The coax feeds with a gamma? and is tuned by a stepper motor tuning the vacuum variable cap. Depending on which of the three models, it operates from 1.5-10 MHz, 2.7-15.5 MHz, or 4.5-22 MHz at up to 150 watts. The technical notes have more interesting details: http://stealth.ae/plugins/custompage...cles.php?id=10 It seems to me a homebrew version could be made for base use such as for those in restricted homes. Placed on the peak of the house, the ground side could be a wire across the top of the peak and the loop lift up during use so it would not attract too much attention to the neighbors. Since the roof of a house is fairly large, a more conventional random length loop tuned with something like a LDG or SGC autotuner at the feedpoint might be a good approach. Icom IC-AH4 could probably also work. I wonder what the size and cost of the Vacuum variable is to make a similar antenna?? size of a pickle jar Several hundred dollars, depending on size, power handling, and source.. http://www.surplussales.com/VaccumVarCaps/VVC5.html http://www.mgs4u.com/RF-Microwave/va...citors-500.htm plus you'll need to cobble up a motor and drive system. the $300 or so for a autotuner starts to look like a good deal. http://www.hamradio.com/web/newcat/hrocat7.pdf Buck N4PGW |
Stealth Loop antenna
Jim Lux wrote:
Buck wrote: This is an interesting antenna. It is a mobile stealth magnetic loop antenna. http://stealth.ae/plugins/custompage...categories=136 I watched the video and checked out the details. The antenna is basically a loop with the roof of the car (the bottom of the luggage rack) as the ground side of the loop, the antenna goes up, folds over the top and back down to the other side of the roof where it feeds thru a high voltage vacuum variable capacitor back to ground. Actually, at 150W, it might not be using a vacuum variable, just a suitable air variable with big spacing. Electrically, this is much the same as the AEA isoloop or MFJ-1782 type antenna. The ARRL antenna book has a whole chapter on them, generically. |
Stealth Loop antenna
Look up DDRR Antenna at ARRL. It works as a very short top-loaded vertical resonated with a capacitor. Ken Fowler, KO6NO I hadn't associated it with the DDRR antenna. I am familiar with it a little. Is this a variation of that? I recognize that any small, and most stealth antennas will be compromise antennas, but then, isn't any antenna a compromise to some degree. -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
Stealth Loop antenna
On Fri, 21 Mar 2008 15:50:45 -0700, Jim Lux
wrote: Buck wrote: This is an interesting antenna. It is a mobile stealth magnetic loop antenna. http://stealth.ae/plugins/custompage...categories=136 Isn't this like the Q-Mac antenna sold in Australia? http://www.qmac.com/mobile_antennas.html They sure look the same. Since the roof of a house is fairly large, a more conventional random length loop tuned with something like a LDG or SGC autotuner at the feedpoint might be a good approach. Icom IC-AH4 could probably also work. That is certainly an idea I hadn't thought of. It sounds cheaper and easier to build. The same concept could be used with raising and lowering the antenna, but instead of a 'loop', it could be a wire. Thought: let's assume one puts up a loop on the roof. The ground side is a single wire running over the peak of the house roof, folds up at 90 degrees for 3-6 feet, back across the roof 6 foot above the peak and back down to the hot lead of the autotuner. Would that not circumvent the need for the capacitor at the far end? and would the loop have to be trimmed to a particular size to operate the various bands, or could the tuner actually operate with most any size loop. Disclaimer: I know from experience that some random lengths might not work on all bands, but some do appear to. I recognize that there could be inefficiencies... I wonder what the size and cost of the Vacuum variable is to make a similar antenna?? size of a pickle jar Several hundred dollars, depending on size, power handling, and source.. http://www.surplussales.com/VaccumVarCaps/VVC5.html http://www.mgs4u.com/RF-Microwave/va...citors-500.htm plus you'll need to cobble up a motor and drive system. the $300 or so for a autotuner starts to look like a good deal. http://www.hamradio.com/web/newcat/hrocat7.pdf I tend to agree with you here :) Buck N4PGW This is what I was fishing for. Maybe the antenna design isn't the best, but the discussion is introducing variations of thinking that could be useful. Thank you Buck -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
Stealth Loop antenna
Buck wrote:
On Fri, 21 Mar 2008 15:50:45 -0700, Jim Lux wrote: Since the roof of a house is fairly large, a more conventional random length loop tuned with something like a LDG or SGC autotuner at the feedpoint might be a good approach. Icom IC-AH4 could probably also work. That is certainly an idea I hadn't thought of. It sounds cheaper and easier to build. The same concept could be used with raising and lowering the antenna, but instead of a 'loop', it could be a wire. Thought: let's assume one puts up a loop on the roof. The ground side is a single wire running over the peak of the house roof, folds up at 90 degrees for 3-6 feet, back across the roof 6 foot above the peak and back down to the hot lead of the autotuner. Would that not circumvent the need for the capacitor at the far end? and would the loop have to be trimmed to a particular size to operate the various bands, or could the tuner actually operate with most any size loop. Probably would work ok. The other approach would be a more conventional dipole looking thing, with the tuner in the middle. To a first order, they'll work the same. A long skinny (much wavelength wide) loop looks a lot like a folded dipole. So, how well it works will probably be determined more by what impedance happens to appear at the feedline, and how well the tuner matches it. If the tuner's at the end (either of the skinny loop or a long random wire) then the impedance tends to be high (close to resonance). If it's in the middle, it's low. In your situation, I might be tempted to try hanging a vertical wire down the side of the house, hooked to one side of the tuner, and the other horizontalish wire 6 ft off the roof. RFI/EMI might be an issue.. You could also do something like run a couple wires on the roof at right angles to the ridge line, hook those to one terminal of the tuner, then hook your wire running along the ridge to the other terminal. I've fooled around a lot with various "throw the wire on the roof" situations (out of laziness, more than anything), and, in general, it seems to work better (no quantititive results) when it looks more like a fan dipole (feedpoint in the middle-ish) than a loop (feedpoint on the edge). |
Stealth Loop antenna
On Mon, 24 Mar 2008 08:49:49 -0700, Jim Lux
wrote: I've fooled around a lot with various "throw the wire on the roof" situations (out of laziness, more than anything), and, in general, it seems to work better (no quantititive results) when it looks more like a fan dipole (feedpoint in the middle-ish) than a loop (feedpoint on the edge). My original post was to generate topics on the antenna design and/or equivalent or better stealth alternatives. I don't really need to drop the wire, but that too is a good idea. As for the 'fan dipole' you like, I have been using the horizontal version throughout my 30 years of ham radio. I learned about the two-wire version as a novice when I was first licensed. 80 meters cut for the Novice frequencies also doubled as a 10 meter dipole. 40 meters cut at the lower end of the Novice frequencies doubled as a 15 meter antenna. As a General Class operator, I discovered I not only had to add an element for 20 meters, but the 75 meter dipole didn't work on 10 and the 40 meter dipole didn't work on 15 meters ??? Then I learned about where the harmonics fell. By the time I became Advanced class, we had three new WARC bands. Along with 75, 80, 40, 30, 20, 17, 15, 12, & 10 meters comes 9 wires or an antenna tuner. I never did like antenna tuners. I always wanted one antenna to do it all. It is amazing how quickly I fell in love with my tuner, though, when I hung a 130 foot dipole about 100 feet high center fed with 300 ohm twin lead. I learned to tune the antenna almost as quickly as I could throw an antenna switch a couple of times. Now that auto-tuners are about as inexpensive as the manual tuners, I am awfully tempted to wander over to the SGC shelf at one of the ham stores and try it out. I am moving to a new house soon. We will be restricted in antennas only to the extent that we don't make the yard look too ugly. It isn't terribly well suited for many antennas, but I do hope to put up at least one decent fan-dipole, more accurately parallel dipole. I don't think I can fit a full-wave loop, due to lack of supports, but it looks like I'll have a place outside my window where a row of trees can support a 60 foot or so high dipole.... I still have a 100 foot roll of 300 or 450 ohm window line :) I guess I digressed. 73 for now Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
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