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Re: Optimum Size Loop ?
John Popelish
roguerat1 wrote:
I'm going to build a passive inductive am bcb loop ant. Is there anAs long as your loop has a circumference much less than a wavelength, then larger is better. Think of this as an energy density problem. the passing waves contain a certain energy per volume of space. the larger the antenna, the larger volume of space it can extract energy from. But as its total conductor length approaches a significant fraction of a wavelength, it ceases to be a classic loop antenna (where the current can be assumed to be nearly uniform around the loop at any instant). Then the radiation pattern changes as various parts of the loop have different phases of a wave on them, and interact with different phases of the passing wave. |
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Re: loop with a coil
Hello John, Jim and Len,
Thanks for your input. When I looked at those photos I at first thought it was for transmitting, however the air capacitor kind of threw that out for me. Since the loop antenna I am building (my first) is for listening to am only it will be without the coil. Thanks again I always enjoy info from knowledgeable sources. Ed Dawson |
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Re: i am a new member in this group
At 10:23 am ((PDT)) Sun Jun 17, 2007, egza_eng2000 wrote:
i study communication engineeringNo, unless you live under a very repressive regime, you need Google's help (or your own choice of major search engine). Then you may search to your heart's content and, if you should locate ARRL HANDBOOK 2001, you will find chapter 20 covers Antennas & Projects. Further ingenuity might find the ARRL Antenna Book as "ARRL ANTENNA HANDBOOK", if you know enough Spanish to invite yourself in as guest. This has 28 chapters on antenna topics. Chapter 5, Loop Antennas, covers the interest of this group, so do at least skim thorough it before you come back to us with any questions on loops. Good luck with your project! Regards, LenW -- Content of a follow-up post should exceed quoted content. (rfc1855) |
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Re: Loop antenna with coil
At 12:41 pm ((PDT)) Sun Jun 17, 2007, ewdawso_1 wrote:
In the photo section under passin_thru2 ther is a loop antenna, 3rdSeems to be these two: (I hope those links hold up ;-) In the photo it shows a coil, just looks like heavy gauge wire coiled,This was asked about and partially answered in the thread "i posted 2 pictures of a loop i found surfing, what is the little coil ?" on Nov 16, 2006, messages 2867 and 2868: The whole tuned circuit seems to be made out of heavy-duty parts, so I suspect it is a small transmitting loop, though the capacitor appears to be air-spaced and hence not able to withstand a very high peak voltage, so it must be QRP. The coil at the base is clearly in series with the loop antenna, so it lowers the resonant frequency compared with the loop and capacitor alone. However, contrary to the suggestion that the alligator clip is for varying the inductance, I believe it is at the end of what appears to be a coaxial cable which enters from the lower right rear, which means the small coil is a matching/loading coil. To me, this makes it seem more likely that this is a transmitting antenna, since it is usually not necessary to match a receiving loop with any exactitude. As to what frequency it's on, I suppose one could estimate the dimensions from clues in the photographs and guess the value of the capacitor, but at a glance I would say it looks a bit small for MW BCB and the capacitor is nearly fully open - and what frequencies may one legally transmit on anyway? So I would guess that it is for 1.8MHz or 3.5MHz - it doesn't really matter, because if you want to copy it, it is fairly easy to start from scratch with the basic mechanical idea using standard loop and coil design programs. Regards, LenW -- Content of a follow-up post should exceed quoted content. (rfc1855) |
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Re: Loop antenna with coil
Jim Dunstan
At 03:18 PM 6/17/2007 -0700, you wrote:
It looks as though adding more wire, either in the form of a coil orHi Ed, Well the loop and coil are in series which will create a combined (A + B) inductance. Adding or shorting turns on the small inductor would have the effect of adding or subtracting a partial turn on the loop .... how much will depend on the ratio of the inductors. I would guess that the inductance of the loop is much greater than the 'side' coil inductor and thus it's effect would be rather small in affecting the tuning range of the overall circuit. A direct response to your question is: The side coil in the photo provides an interesting conversation piece. As a side light, it is possible to adjust the inductive reactance of a coil by putting a capacitive reactance (capacitor) in parallel with it. Of course when they equal each other they are said to be 'resonant'. If you put a capacitor and inductor in series and adjust the capacitor to resonance at a particular frequency as in an 'L network', the ratio of the capacitance to inductance can provide impedance transformation (commonly used in antenna tuners). Since it is much easier to obtain variable capacitors than variable inductors an old trick is put a variable capacitor in parallel with the inductor. This second capacitor cancels some of the inductive reactance of the coil giving the effect of a variable inductor .... common in the Z-match antenna tuner. Jim, VE3CI |
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Trap for 160/80m loop ?
Sam
I want to use a ~265 foot horizontal 80m closed loop, on 160m
what I need/want to do is open the far side of the loop when it is operated on 160m and close it for 80m and above how do I do that? the loop is and has to be coax fed not a situation where ladder line can be used!!!!! TIA ka5oai |
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Re: Loop antenna with coil
John MacKay
It looks as though adding more wire, either in the form of a coil or additional turn(s) on the loop itself would have the effect of lowering the top and bottom freqs thus altering the freq range of the loop. VE7AFN.
noswadplease <ewdawso_1@...> wrote: Hi Group, In the photo section under passin_thru2 ther is a loop antenna, 3rd and 4th photo that shows an octagon loop antenna. In the photo it shows a coil, just looks like heavy gauge wire coiled, that is between the antenna and the variable capacitor. Does anyone know what this loop is for or what it could possibly be used for? I am currently in the final stages of building a loop from pvc for am dxing. Ever since I saw that picture it has intrigued me. If anyone knows the purpose please respond. Apparently passin_thru2 didn't know either. Ed Dawson --------------------------------- Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. |
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Loop antenna with coil
Hi Group,
In the photo section under passin_thru2 ther is a loop antenna, 3rd and 4th photo that shows an octagon loop antenna. In the photo it shows a coil, just looks like heavy gauge wire coiled, that is between the antenna and the variable capacitor. Does anyone know what this loop is for or what it could possibly be used for? I am currently in the final stages of building a loop from pvc for am dxing. Ever since I saw that picture it has intrigued me. If anyone knows the purpose please respond. Apparently passin_thru2 didn't know either. Ed Dawson |
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Re: i am a new member in this group
John MacKay
This message has a count of 17K but I read only 3 or 4K. Am I missing something ? John M.
egza_eng2000 <egza_eng2000@...> wrote: i am eme i study communication engineering my project about antenna i need your help to have searchs about types of antenna --------------------------------- Got a little couch potato? Check out fun summer activities for kids. |
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Re: Wellbrook's after-sales service
D.Kremp
Hi Nigel,
toggle quoted message
Show quoted text
I don't want to add fuel to the fire but please don't play on words ! I'm sure you are clever, intelligent and positive minded enough to understand what I mean in my post without further explanations. 73's + have a nice week end Dominique KREMP from Normandy/France _____ De : loopantennas@... [mailto:loopantennas@...] De la part de gandalfg8@... Envoy¨¦ : jeudi 14 juin 2007 09:26 ? : loopantennas@... Objet : Re: [loopantennas] Wellbrook's after-sales service In a message dated 14/06/2007 04:14:07 GMT Daylight Time,
dominique.kremp@ <mailto:dominique.kremp%40wanadoo.fr> wanadoo.fr writes: I have been reading here and there for some weeks some critical posts against Any IKIN in various Yahoo lists concerning the way he protects his antennas patents. First of all I find it's unfair because it's HIS work, these patents are HIS property and everybody would do the same at his place. Then let me say that I never experienced in our hobby such a company like his which supports the customers so friendly and so quickly when they have a problem ! I'm sure I'm not the only one ! Just bear that in mind if you are prone to criticize him ! ---------------------------------------- Whilst glad to hear you got your antenna fixed, and happy to agree that it's also my experience and that of others I know that Andy can be very helpful and that his antennas are very good, you also need to get your facts straight. Nobody here criticised him for concealing the contents of his antenna amplifier, that's his choice and something he's perfectly entitled to do. Of course he wants to protect his designs, and so would I. Previous comments arose because of his rather heavy handed approach to one group member following the usual ongoing speculation as to the configuration of that amplifier, and his suggestion there was some kind of conspiracy afoot. I can understand his concern, a broken unit had been taken apart and the contents photographed, with speculation probably running higher than it had for some time, but the most significant point you seem to have missed from previous comments is that there are NO patents, NO intellectual property rights, NO whatever. That was what became the temporary focus of the discussions you refer to, at least in this group, not any personal criticism. Reading's one thing, understanding is obviously something different!!! regards Nigel GM8PZR [Non-text portions of this message have been removed] ---------------------------------------------------------------------------- ----------- Orange vous informe que cet e-mail a ¨¦t¨¦ contr?l¨¦ par l'anti-virus mail. Aucun virus connu ¨¤ ce jour par nos services n'a ¨¦t¨¦ d¨¦tect¨¦. [Non-text portions of this message have been removed] |
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Re: Wellbrook's after-sales service
In a message dated 16/06/2007 16:49:13 GMT Daylight Time,
dominique.kremp@... writes: Hi Nigel, I don't want to add fuel to the fire but please don't play on words ! --------------------------------------------------------- I don't see how it should be considered "playing on words" when all I did was point out that comments such as those below, with your emphasis included, demonstrate a lack of understanding of the previous discussions on the subject. If I'd wanted to be unkind I might perhaps have queried whether or not it was a more deliberate distortion of what was said. --------------------------------------------------------------- I have been reading here and there for some weeks some critical posts against Any IKIN in various Yahoo lists concerning the way he protects his antennas patents. First of all I find it's unfair because it's HIS work, these patents are HIS property and everybody would do the same at his place. Just bear that in mind if you are prone to criticize him ! ---------------------------------------- As I took some part in those discussions, and am well aware of what was said, I don't think it unreasonable if I then respond to misinformed comment. regards Nigel GM8PZR |
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Re: Active loop antenna
How can I get a schematic for the Degen DE-31 active antenna? Anyone
nice enough to email me a copy? mwmwmfilms@... Thanks Chris --- In loopantennas@..., "Ralph Lane" <rlane7301@...> wrote: in the and GIFLinks rather than uploading the file. into Photos. Please convert BMP or TIF to JPG or GIF before uploading. |
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Wellbrook non-patents
If the Wellbrook amplifier was in fact patented, the advertising would say so,
and i don't think i have ever seen that. It would probably still be wise to "pot" it (epoxy encase it), because any patents still wouldn't protect it from being copied in China, and the epoxy also protects the amplifier from the weather. -Hue Miller / Newport, Oregon |
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Re: Commercial loop antenna for VLF - 24KHZ
John Stumm
--- In loopantennas@..., "Carl" <carlm01@...> wrote:
KHZ or other VLF radio frequencies? I have looked at Palomar, and AOR butCarl, Welcome to the group. You might want to check Stormwise. (Stormwise.com). They sell whole antennas or large cores that could allow you to possibly wind your own? or is a commercial one really needed. If you're up for experimenting, let me know if you need some wire, clothbound, teflon, enammeled, coil forms? you name it, I can probably help you out - just pay the shipping. What's the age range of your school group? I'm alway up for helping worthy causes... A couple other interest groups you can check out for ideas/expertise are: ferriterodantennaexperimenters group (semi-active but lots of good archived info) VLF_group (more activity and info). Regards, John |
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Re: Wellbrook's after-sales service
Stephen Bass
I have also experienced the same level of service with my Wellbrook loops.
On multiple occasions, either my loop, the amp unit or the interface has developed a problem. In each case after he worked with me to identify which piece was causing the problem, Mr. Ilkin cheerfully replaced the culprit. Thus, I agree with Dominique that never have I had better customer support from ANY shortwave supplier than Andy Ilkin. Steve Bass |
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Re: Wellbrook's after-sales service
In a message dated 14/06/2007 04:14:07 GMT Daylight Time,
dominique.kremp@... writes: I have been reading here and there for some weeks some critical posts against Any IKIN in various Yahoo lists concerning the way he protects his antennas patents. First of all I find it's unfair because it's HIS work, these patents are HIS property and everybody would do the same at his place. Then let me say that I never experienced in our hobby such a company like his which supports the customers so friendly and so quickly when they have a problem ! I'm sure I'm not the only one ! Just bear that in mind if you are prone to criticize him ! ---------------------------------------- Whilst glad to hear you got your antenna fixed, and happy to agree that it's also my experience and that of others I know that Andy can be very helpful and that his antennas are very good, you also need to get your facts straight. Nobody here criticised him for concealing the contents of his antenna amplifier, that's his choice and something he's perfectly entitled to do. Of course he wants to protect his designs, and so would I. Previous comments arose because of his rather heavy handed approach to one group member following the usual ongoing speculation as to the configuration of that amplifier, and his suggestion there was some kind of conspiracy afoot. I can understand his concern, a broken unit had been taken apart and the contents photographed, with speculation probably running higher than it had for some time, but the most significant point you seem to have missed from previous comments is that there are NO patents, NO intellectual property rights, NO whatever. That was what became the temporary focus of the discussions you refer to, at least in this group, not any personal criticism. Reading's one thing, understanding is obviously something different!!! regards Nigel GM8PZR |
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Wellbrook's after-sales service
D.Kremp
Hi all,
I just want to tell you what happened to me with my 2 years old ALA1530. I had been experiencing for a couple of months that its sensivity was very low when I switched it on. I had to disconnect the BNC connector which goes from the interface to the antenna and to connect it again to get full sensivity. Switching the interface out and on did'nt help at all. The difference was about -15 dBm. I sent a mail to Wellbrook Communication and got a prompt reply from Andy IKIN himself 2 hours later. In his opinion the Head Ampl. had an intermitent fault. He told me therefore to cut the aluminium loop at each side of the white box (which I did trembling all over !!!) and to return it back to him. The last thing (but not the least !) he told me is that he was going to send to me a new unit with the required instructions to fit it to the loop. 4 days later the new unit arrived as "priority handling & registered delivery". It was a brand new one, not a refurbisched or a 2nd hand one as expected ! I could fit it again very easily, I installed it and tested it immediately. Waooh !! What a surprise ! I never got such a sensivity with the former one, even when I installed it the very 1st time ! Incredible ! As if it were a completely different circuit ! I forgot to mention something important: I didn't have to pay for anything, neither for the new unit nor for postage (?8.38) !!! I have been reading here and there for some weeks some critical posts against Any IKIN in various Yahoo lists concerning the way he protects his antennas patents. First of all I find it's unfair because it's HIS work, these patents are HIS property and everybody would do the same at his place. Then let me say that I never experienced in our hobby such a company like his which supports the customers so friendly and so quickly when they have a problem ! I'm sure I'm not the only one ! Just bear that in mind if you are prone to criticize him ! Have a nice day/evening Dominique from Normandy/France PS: Please note that I don't have any connection at all to this company ! [Non-text portions of this message have been removed] |
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