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Linear decoupling traps
On Tue, 15 Apr 2008 13:46:08 -0500, Cecil Moore
wrote: Modeling real-world lossy stubs seems to violate EZNEC's guidelines. How does one do it? One does not get hyperbolic about trivialities. |
Linear decoupling traps
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----------------------------------------xxcenterxxx---- I_________ OR ----------------------------------------xxxxcenterxxx------ ________I 73 Jouko OH5RM Different text sizes seem to destroy the graphics, I used the medium size in Outlook express. Anyway the upper is OK , the lower should look like this ______________________________________/center/_____ ___________I OH5RM |
Linear decoupling traps
On Wed, 16 Apr 2008 09:21:13 +0300, "JN" wrote:
. ----------------------------------------xxcenterxxx---- I_________ OR ----------------------------------------xxxxcenterxxx------ ________I 73 Jouko OH5RM Different text sizes seem to destroy the graphics, I used the medium size in Outlook express. Anyway the upper is OK , the lower should look like this ______________________________________/center/_____ ___________I OH5RM from OP My question: Is there any difference if the shorted end is pointing to the center or to the tip of dipole. Only the stub portion has two wires in parallell, the rest is only one wire. Jouko, I noticed this thread took a detour, but I never saw anyone actually try to answer your question. I too, am looking to see the answer on this. It is amazing, all this talk about a Lattin antenna, that appears to have lots of sites talking about how it works, but no one actually having built one or used one, and a simple "yes" or "no" would answer your question. I don't have the answers or the means of testing one at this time. If you get the answer direct, please post it here. Thanks Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
Linear decoupling traps
Jouko, I noticed this thread took a detour, but I never saw anyone
actually try to answer your question. I too, am looking to see the answer on this. 73 for now Buck, N4PGW www.lumpuckeroo.com Yes Buck it is often difficult to get an answer just to the question you are asking. Anyway very soon all snow has melted away here and then its possible to testbuild it. 73 Jouko OH5RM |
Linear decoupling traps
"JN" wrote in message ... Jouko, I noticed this thread took a detour, but I never saw anyone actually try to answer your question. I too, am looking to see the answer on this. 73 for now Buck, N4PGW www.lumpuckeroo.com Yes Buck it is often difficult to get an answer just to the question you are asking. Anyway very soon all snow has melted away here and then its possible to testbuild it. 73 Jouko OH5RM Hi Jouko I thought Richard's statement that modeling would tell you about how the design might perform, was good advice. If you use EZNEC, I'd be willing to help you if you dont already know how to use it to model your antenna. Jerry KD6JDJ |
Linear decoupling traps
On Wed, 16 Apr 2008 17:01:24 +0300, "JN" wrote:
Jouko, I noticed this thread took a detour, but I never saw anyone actually try to answer your question. I too, am looking to see the answer on this. 73 for now Buck, N4PGW www.lumpuckeroo.com Yes Buck it is often difficult to get an answer just to the question you are asking. Anyway very soon all snow has melted away here and then its possible to testbuild it. 73 Jouko OH5RM Repeated message seeing that you both missed it: On Tue, 15 Apr 2008 21:44:02 +0300, "JN" wrote: I understand that you would suggest 90 degree? But does it really matter? Hi Jouko, At right angles, yes. Does it matter? That depends on proximity to other conductors, including itself if you "coil" it around the radiator, or along the radiator. When I looked at your first posting, I was confused by the single wire, and the text graphics should have been done in fixed font. Keep the line conductors at least 3, preferably more, wire diameters from the radiator or themselves. Use the largest diameter for the multiplier of 3 (or more). 73's Richard Clark, KB7QHC 73's Richard Clark, KB7QHC |
Linear decoupling traps
Richard Clark wrote:
Cecil Moore wrote: Modeling real-world lossy stubs seems to violate EZNEC's guidelines. How does one do it? One does not get hyperbolic about trivialities. Is 24 dBi omnidirectional gain from a vertical antenna enough to "get hyperbolic about trivialities"? http://www.w5dxp.com/SUPRGAIN.EZ -- 73, Cecil http://www.w5dxp.com |
Linear decoupling traps
HI
Theory says that whatever condition exists at far end of 1/4 wave stub will appear at fed end. ie. if far end is left open a high impedance will appear at fed end, at resonant freq. So it would appear that the shorted end should be nearest to feed point of antenna. The centre of dipole or bottom of a vertical. Hope that makes sense!................................Rod EI3CZ |
Linear decoupling traps
I thought Richard's statement that modeling would tell you about how the
design might perform, was good advice. If you use EZNEC, I'd be willing to help you if you dont already know how to use it to model your antenna. Jerry KD6JDJ Jerry, thanks for the offert. I dont know how good these modelling programs are in this situation. But if it is easy, so could somebody do the following: Take 20m of wire, that is half of a dipole. Put a 1/4 electric wavelength shorted stub for 10,1MHz so that the open end is 7,25m from center and the shorted end pointing to the tip of antenna. One side of stub is the 20m wire itself, like in the upper picture. Ignore all velocity factors to make it sinple. Now tell me what are the resonance frequencies of that kind of element and if possible feed point impedande (80m and 30m) I know I could do it myself but as you know learning to use a new program reliably takes lot of time. 73 Jouko OH5RM |
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