Anybody following the Dallas Files
On Monday, July 18, 2011 4:07:09 PM UTC-5, amdx wrote:
On 7/18/2011 9:58 AM, wrote: On Sunday, July 17, 2011 3:49:46 PM UTC-5, Sal wrote: OK, so the final score is Dallas 3, Me 0. Game over. *sigh* "Sal" Now you see why I will not have anything to do with a "group" that you must sign up for. Never have, and never will. In trying to avoid such a simple request, you deny yourself a great many sites. I'll survive.. :/ Many of them seem to like to play their silly games, have control over what is posted, banish the hecklers, etc.. No way to live as far as I'm concerned. I don't see this as reason to deny yourself access to hundreds or thousands of sites that have great information. Who says it's all great information? Some may be. Some may not. I'm not going to jump through hoops to find out one way or the other. And I don't need him to learn about phased broadcast band antennas. I want to learn, do you have any sites with good broadcast band antennas. Well...Google is your friend.. He's not the only one to run those ya know.. http://search.yahoo.com/search;_ylt=...8&fr=yfp-t-701 I'm sure I can gather some usable info without having to jump through a hoop. It's not like he invented them or anything. He's not claiming invention, but he has made a nice contribution to the hobby. No problem with that. But I'm not going to be a spectator if I have to jump through hoops, be censored, moderated, vetted, etc, ad nausium.. :+ He's just tinkering with a few, and I presume posting his results to the few that he deems worthy.. :/ Tinkering seems a little insincere, I'm sure he ha smany hundreds of hours into his research. He probably does. But what does that have to do with me? Please post any websites you have regarding broadcast band antennas. I have not found much other than resonant loops and beverages. Mikek Already gave one example above. I think W8JI was using some sort of steerable verticals, and he might have some info on his site. As I recall, they were pretty short, and maybe not even resonant, but I don't recall how he was steering them. There is tons of stuff out there.. And there is always that source many seem to ignore these days. Books. Myself, I happen to like loops.. I'm more interested in a good null, than I am a really directional pattern like a flashlight. I don't have the room to run a decent beverage here. I can do it at my dirt patch out in the sticks, but I've never got around to stringing the wire up. I intend to do it one of these days just to give em a try. Anyway, I've been fairly satisfied just using the various loops I have for general AM-BC use. If I decide to build something a tad more exotic, I'll dig up the info, and I won't be jumping through hoops to get it. Plenty of other flag array users out there. No need for me to bother Dallas about it. |
Anybody following the Dallas Files
On 7/18/2011 6:50 PM, amdx wrote:
I still want to learn, do you have a specific site with a good broadcast band receiving antenna. Preferably with a null I can rotate and that will fit in 150 ft. how deep a null, how narrow/wide? One of the noise canceling boxes with two antennas will do quite well. Timewave ANC-4 is one possibility MFJ 1026 is another. DX engineering NCC-1 For BC band, almost any antenna will work. If you want physically small you could use any of the active antennas.. You could use a MFJ1020C,1022,1024, Ameco TPA, DX Engineering ARAV3-1P, etc. The MFJ 1026 canceller includes an antenna. A whole bunch of kits out there.. Ramsey AA7B, the Amrad antenna, .. If you want to get more sophisticated, some sort of software receiver might be better approach (you could use more than 2 antennas, for instance). There's not much off the shelf, but if you're ambitious you might look at K1LT's array using softrock receivers.http://www.k1lt.com/ |
Anybody following the Dallas Files
On Tue, 19 Jul 2011 12:12:52 -0700, Jim Lux wrote:
On 7/18/2011 6:50 PM, amdx wrote: I still want to learn, do you have a specific site with a good broadcast band receiving antenna. Preferably with a null I can rotate and that will fit in 150 ft. how deep a null, how narrow/wide? One of the noise canceling boxes with two antennas will do quite well. Timewave ANC-4 is one possibility MFJ 1026 is another. DX engineering NCC-1 In BCB SWLing you want the null(s) deep (and steerable) to kill the strong, unwanted station. Jonesy |
Anybody following the Dallas Files
On 19 Jul 2011 20:55:42 GMT, Allodoxaphobia
wrote: In BCB SWLing you want the null(s) deep (and steerable) to kill the strong, unwanted station. This characteristic demands the SAME considerations as required for a sharp beam of high directionality. If we were to select the antenna that matches your quoted specs above, it would be called the Cardiod (example available in EZNEC). Problem there is the 30dB null isn't steerable (not enough elements). And it is large (too large for the back yard): 1. Too tall for most to build. 2. Elements too far apart (out of necessity for, dare I say it? Phasing). As it is designed as a transmit antenna, too tall is quickly dismissed. You can use as short of one as proves useful. The first element, now being shorter, also allows us to add any number of shorter elements in an array around (or mixed in with) the first. This brings steerability. The more elements, the better angle resolution and null depth control. You can pull the additional elements (if only one more to build a proof of concept Cardiod) closer to the first (dismissing the large spacing objection), and introduce the necessary time/phase control through: 1. cabling; 2. analog delay circuits; 3. digital delay circuits. Moving to a digital solution controls all variables. If none of this is covered in the "Dallas Files," it would be best to leave them in the File Cabinet. Jim has provided adequate links to fill in the gaps and no one was injured in the process of obtaining the information. 73's Richard Clark, KB7QHC |
Anybody following the Dallas Files
On 7/19/2011 3:47 PM, Richard Clark wrote:
On 19 Jul 2011 20:55:42 GMT, Allodoxaphobia wrote: In BCB SWLing you want the null(s) deep (and steerable) to kill the strong, unwanted station. This characteristic demands the SAME considerations as required for a sharp beam of high directionality. Actually, no. You can form a deep null with a much simpler antenna system than for high directionality. All you need is to "cancel" the signal from the undesired direction. If you had two verticals spaced some distance apart, fed by equal length transmission lines, and one is polarity reversed, you get a fairly sharp null on the line perpendicular to the line between the antennas. (e.g. a signal coming from broadside will exactly cancel in the combining) A loopstick antenna on a ferrite core or a multiturn loop, as popular in direction finding, is another example with a fairly sharp null. Now.. if you want one null, and one null only, that gets a bit trickier in a small space. I don't know that you can do it with only two elements (haven't thought about it much). And if you want to steer the null. One traditional approach in direction finding is to use a goniometer or an adcock array. If we were to select the antenna that matches your quoted specs above, it would be called the Cardiod (example available in EZNEC). Problem there is the 30dB null isn't steerable (not enough elements). And it is large (too large for the back yard): 1. Too tall for most to build. 2. Elements too far apart (out of necessity for, dare I say it? Phasing). that's the "one null and one null only" problem. |
Anybody following the Dallas Files
On Tue, 19 Jul 2011 17:45:01 -0700, Jim Lux
wrote: On 7/19/2011 3:47 PM, Richard Clark wrote: On 19 Jul 2011 20:55:42 GMT, Allodoxaphobia wrote: In BCB SWLing you want the null(s) deep (and steerable) to kill the strong, unwanted station. This characteristic demands the SAME considerations as required for a sharp beam of high directionality. Actually, no. You can form a deep null with a much simpler antenna system than for high directionality. Simpler does not invalidate SAME consideration. All you need is to "cancel" the signal from the undesired direction. If you had two verticals spaced some distance apart, fed by equal length transmission lines, and one is polarity reversed, you get a fairly sharp null on the line perpendicular to the line between the antennas. (e.g. a signal coming from broadside will exactly cancel in the combining) Hence my referenced Cardiod antenna available for modeling with EZNEC. A loopstick antenna on a ferrite core or a multiturn loop, as popular in direction finding, is another example with a fairly sharp null. Mike has explicitly rejected loop solutions. Now.. if you want one null, and one null only, that gets a bit trickier in a small space. I don't know that you can do it with only two elements (haven't thought about it much). And if you want to steer the null. One traditional approach in direction finding is to use a goniometer or an adcock array. Something I've already offered (Bellini Tosi Antenna, as well as Wullenweber) - and has been rejected/ignored. Repetition doesn't seem to stand much chance against the ongoing cult examination in trying to parse the entrance qualifications for the Dallas Files. If we were to select the antenna that matches your quoted specs above, it would be called the Cardiod (example available in EZNEC). Problem there is the 30dB null isn't steerable (not enough elements). And it is large (too large for the back yard): 1. Too tall for most to build. 2. Elements too far apart (out of necessity for, dare I say it? Phasing). that's the "one null and one null only" problem. Which loops (as in recurse, not a pun) us back to the top. 73's Richard Clark, KB7QHC |
Anybody following the Dallas Files
On 7/19/2011 8:08 PM, Richard Clark wrote:
If you had two verticals spaced some distance apart, fed by equal length transmission lines, and one is polarity reversed, you get a fairly sharp null on the line perpendicular to the line between the antennas. (e.g. a signal coming from broadside will exactly cancel in the combining) Hence my referenced Cardiod antenna available for modeling with EZNEC. Cardioid has only a single null and is a "end fire" configuration. I don't think (esp with short spacing) you can get as deep or narrow a null as with a W8JK style antenna(short spacing, out of phase). two 180 degree out of phase antennas can be very narrow, even with small physical extent. A loopstick antenna on a ferrite core or a multiturn loop, as popular in direction finding, is another example with a fairly sharp null. Mike has explicitly rejected loop solutions. Perhaps big loops were rejected.. what about physically small loops. Now.. if you want one null, and one null only, that gets a bit trickier in a small space. I don't know that you can do it with only two elements (haven't thought about it much). And if you want to steer the null. |
Anybody following the Dallas Files
On 7/20/2011 8:01 PM, Jim Lux wrote:
On 7/19/2011 8:08 PM, Richard Clark wrote: After reading too many postings from this thread I wonder why anyone, excepting myself just for this once, bothers to comment. Who bleeping cares about this thread? This is not a great debate even if you consider any of the the best ones here "great debates". Which they mostly aren't. tom K0TAR |
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