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#11
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Would a discone cover all the US TV broadcast Freqs?
I like making my own also - so would a few 'nested loop' antennas cover the tv broadcast band? But there goes the stealth. Huh? You think a couple brass welding rods in loops are more noticable than a couple discone antennas mounted base to base? ! And if you painted them black, they'd be invisible. Ed |
#12
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Would a discone cover all the US TV broadcast Freqs?
So - does anyone know of an omni directional horizontally polarized wide band antenna? Had something like that on the roof of my RV. A Wineguard Roadstar 2000 omnidirectional antenna ought to be just what you're looking for. Paint it black, if you want even more stealth. such as at: http://www.amazon.com/Canon-Winegard-Roadstar-2000- Antenna/dp/B000R2YB0G Ed |
#13
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Would a discone cover all the US TV broadcast Freqs?
In article ,
Hal Rosser wrote: If I did that, the omi-directionality (if that's a word) would go away and so would most of the compactness needed foe stealthiness. So - does anyone know of an omni directional horizontally polarized wide band antenna? If you want a truly-omnidirectional (or close to it) antenna, with no significant pattern variation or serious sensitivity variation in frequency over the TV band, horizontally polarized, with no requirement for electronic switching of elements and no mechanical rotator... I sure don't. I skimmed through the antenna designs given in Bailey's "Television and other Receiving Antennas" book a few days ago, and didn't see any which come close to this. I think you're going to have to "give" on at least one of the above issues in order to get something realizable. There are probably a number of approaches: - Use a wideband, rotatable dipole. At least one of the "saucer radome" antennas comes with an internal rotator, control box, and IR remote. You program in the bearing to each station you want, hit a button on the remote, and the rotator swings the (inside-the- radome) elements into line. See the HDMS9100 antenna at the top of the page: http://www.starkelectronic.com/allomni.htm In this approach you give up on "no rotator". Doesn't work terribly well with DVRs, since the DVR may have a scheduled recording to make and can't push the button to rotate the antenna. - Use a wideband dipole (e.g. several dipoles of different lengths, mounted in the same plane, with a common feedpoint), and simply align it in a way which gives you acceptable signal quality for all of the stations you care about. The null off the end of a dipole isn't all that wide, and you may find that you may be able to "aim" these two nulls in a direction which doesn't place any of the transmitters into a substantial null. There may be one or more "compromise" settings in which you get a plenty-good signal on all of the stations. In this approach you give up on true omnidirectionality. I think that the Channel Master 3000A (listed further down on the page above) is of this general sort. If I recall correctly, it has a single folded dipole element internally, with the ends of the dipole swept into an "S" shape in side the radome - this lessens the depth of the null off the end and (I think) makes the direction of the actual null somewhat frequency-sensitive. - Install two such broadband dipoles at 90-degree angles, with a remotely operated switch/relay, and select one or the other depending on channel. Not truly omnidirectional , requires manual switching. - Install two or more dipoles of different lengths, at different angles, with a common feedpoint, with each dipole cut to the frequency of a specific station and aligned broadside to that station's transmitter. The resulting pattern will no doubt have lobes and cancellations, but (if the channels are far apart enough in frequency) will probably work reasonably well. Not truly omnidirectional at any single frequency; needs to be designed for your specific location and frequency considerations. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#14
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Would a discone cover all the US TV broadcast Freqs?
I like making my own also - so would a few 'nested loop' antennas
cover the tv broadcast band? But there goes the stealth. Huh? You think a couple brass welding rods in loops are more noticable than a couple discone antennas mounted base to base? ! And if you painted them black, they'd be invisible. Ed Huh back to you - I never said anything about a 'couple' of discones - my original post was asking whether a discone would be a viable tv antenna. and I mentioned that I wanted to preserve some degree of stealth as well. Your suggestion sounds good - just trying to picture it. That RV antenna is starting to sound good too. |
#15
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Would a discone cover all the US TV broadcast Freqs?
Ed wrote:
So - does anyone know of an omni directional horizontally polarized wide band antenna? Had something like that on the roof of my RV. A Wineguard Roadstar 2000 omnidirectional antenna ought to be just what you're looking for. Paint it black, if you want even more stealth. such as at: http://www.amazon.com/Canon-Winegard-Roadstar-2000- Antenna/dp/B000R2YB0G Ed This is a phased array and can be steered electrically: http://sadoun.com/Sat/Products/Wineg...irectional.htm |
#16
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Would a discone cover all the US TV broadcast Freqs?
Dave wrote:
Ed wrote: So - does anyone know of an omni directional horizontally polarized wide band antenna? Had something like that on the roof of my RV. A Wineguard Roadstar 2000 omnidirectional antenna ought to be just what you're looking for. Paint it black, if you want even more stealth. such as at: http://www.amazon.com/Canon-Winegard-Roadstar-2000- Antenna/dp/B000R2YB0G Ed This is a phased array and can be steered electrically: http://sadoun.com/Sat/Products/Wineg...irectional.htm Here's a bunch of cheapies: http://www.summitsource.com/outdoor-...-47_57_65.html |
#17
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Would a discone cover all the US TV broadcast Freqs?
On Wed, 17 Dec 2008 20:06:03 GMT, "JB" wrote:
Discone is vertically polarized and TV is horizontal. Results in a 15db or more loss in signal. Usually true. However, a few DTV stations have a vertical component intended to improve mobile TV reception, where a telescoping vertical whip antenna is commonly used. See: http://www.tvtechnology.com/article/article/67946 -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#19
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Would a discone cover all the US TV broadcast Freqs?
Bart Bailey wrote:
In posted on Wed, 17 Dec 2008 21:38:34 -0500, Hal Rosser wrote: Begin my original post was asking whether a discone would be a viable tv antenna. Being an omni, you're going to pick up any ghosts arriving at your location, unlike a directional that can attempt to null them out. ATSC ignores much multipath. |
#20
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Would a discone cover all the US TV broadcast Freqs?
Hal Rosser wrote:
"Cecil Moore" wrote in message ... JB wrote: Discone is vertically polarized and TV is horizontal. Results in a 15db or more loss in signal. How about a dual-discone mounted horizontally? -- 73, Cecil http://www.w5dxp.com If I did that, the omi-directionality (if that's a word) would go away and so would most of the compactness needed foe stealthiness. So - does anyone know of an omni directional horizontally polarized wide band antenna? Somewhat tricky.. Two crossed dipoles fed with the correct phasing is very close to that. Check out "Lindenblad" or "turnstile" |
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