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#1
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6,752 Trenton Military 0213 USB 30/Aug/2004
Aero Wx for Canada (VE) 11,251 RAF Volmet 0107 USB 30/Aug/2004 "This is RAF Volmet...." Continuous Aero Wx. (VE) Automatic Aviation Volmet weather information HF broadcast system. Volmet is French and means "flying weather". DX-394 w/100' longwire ant. Antwerp,NY USA (VE) |
#2
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Vincent Everett wrote:
6,752 Trenton Military 0213 USB 30/Aug/2004 Aero Wx for Canada (VE) 11,251 RAF Volmet 0107 USB 30/Aug/2004 "This is RAF Volmet...." Continuous Aero Wx. (VE) Automatic Aviation Volmet weather information HF broadcast system. Volmet is French and means "flying weather". DX-394 w/100' longwire ant. Antwerp,NY USA (VE) That's a good length of wire. Which direction is it most sensitive in? It was mentioned earlier that real longwire antennas will be sensitive towards the end, while mere 'random' wire antennas are sensitive at ninety degrees to the length. What have you noticed? mike |
#3
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![]() "m II" wrote Vincent Everett wrote: DX-394 w/100' longwire ant. Antwerp,NY USA That's a good length of wire. Which direction is it most sensitive in? It was mentioned earlier that real longwire antennas will be sensitive towards the end, while mere 'random' wire antennas are sensitive at ninety degrees to the length. What have you noticed? That's a question often asked and probably confusing because of the common usage of similar antenna names that tend to blur their differences. I use both random and long wire designs by common-usage definitions. For reception these are nearly as effective as resonant dipoles. "Random" wire antenna is a "means-what-it-says" definition of a good all purpose HF antenna from any length of wire that is convenient or available. It's effectiveness is so close to antennas where wires are cut to specific frequency-components, that for most users it is all they need. The angle the random wire is raised will have an effect on it's directional capabilities, reception being favored toward the low (ground) end of the wire. A high angle (greater than 45 degrees) will eliminate most of the directionality. The closer to vertical the wire, the less directional it's pattern of reception or transmission. A compromise between uni-directional and the high-noise that results from too close to vertical is usually desireable in random wire antennas. "Long wire" is a confusing name, as it implies something that runs cross-country ;-). It is intended to describe a wire antenna that is cut to at least 1/2 wave length, preferrably a full wave length of the desired frequency. In practical use however, it is also used to describe a 1/4 wave or 1/2 wave design length, and it does have some resonance capabilities perhaps slightly improved over the random wire on a specific frequency. But not noticeably better to most users from the 1/4 wavelength standpoint. The angle of the longwire from ground to it's high point affect directionality the same as a random wire, minimizing with increased angle. "Beverage" antenna is the REAL long wire! It is typically multiples of a full-wave length long, and because of this it is almost always close to and parallel with the ground. This antenna is very directional, with patterned lobes and nulls that antenna design programs can easily predict. But, with EVERY piece of wire strung between any two points, some characteristics of all three examples will be achieved! When using the "Random Wire" design, you are simply getting a piece of wire as long as is *practical* for your application (longer and higher off the ground is better). Preferrably, but not required, the length should be at least 1/4 wave of your lowest desired frequency. Use the formula "234 [divided by] desired frequency in megahertz" to arrive at a 1/4 wavelength. 468 divided by desired freq in mhz will provide 1/2 wavelenth dimensions. Jack Painter Virginia Beach VA |
#4
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Longwire - any antenna which uses a single end-fed element which is several
wavelengths long. A longwire is directional toward its far end: More wavelengths long = more directional. I have my longwire pointing SE at approx. 6' high. I also use a preselector/ antenna tuner for fine adjustment. Works very well for me. "m II" wrote in message news:1hxYc.32431$A8.7952@edtnps89... Vincent Everett wrote: 6,752 Trenton Military 0213 USB 30/Aug/2004 Aero Wx for Canada (VE) 11,251 RAF Volmet 0107 USB 30/Aug/2004 "This is RAF Volmet...." Continuous Aero Wx. (VE) Automatic Aviation Volmet weather information HF broadcast system. Volmet is French and means "flying weather". DX-394 w/100' longwire ant. Antwerp,NY USA (VE) That's a good length of wire. Which direction is it most sensitive in? It was mentioned earlier that real longwire antennas will be sensitive towards the end, while mere 'random' wire antennas are sensitive at ninety degrees to the length. What have you noticed? mike |
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