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#1
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nbr wrote:
Why is the horizontal sengment of a 1/2-square considered a "phasing line" and not a radiator? The center of the "phasing line" on a half-square is a maximum voltage point but there is nothing to keep that horizontal wire from radiating. At a TOA of about 65 degrees the broadside horizontal radiation and vertical radiation of a half-square are about equal at about -9 dBi. -- 73, Cecil, W5DXP |
#2
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On Mon, 28 Jul 2003 09:57:42 -0700, W5DXP
wrote: nbr wrote: Why is the horizontal sengment of a 1/2-square considered a "phasing line" and not a radiator? The center of the "phasing line" on a half-square is a maximum voltage point but there is nothing to keep that horizontal wire from radiating. At a TOA of about 65 degrees the broadside horizontal radiation and vertical radiation of a half-square are about equal at about -9 dBi. I don't think you're suggesting the horizontal component is cancelled out??? So in truth the 1/2-square may perform DX best at low angle TOA broadside to the two verticals, but may also have high angle lobes from the horizontal wire (effective close-in cloud-warmer)? |
#3
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nbr wrote:
W5DXP wrote: The center of the "phasing line" on a half-square is a maximum voltage point but there is nothing to keep that horizontal wire from radiating. At a TOA of about 65 degrees the broadside horizontal radiation and vertical radiation of a half-square are about equal at about -9 dBi. I don't think you're suggesting the horizontal component is cancelled out??? So in truth the 1/2-square may perform DX best at low angle TOA broadside to the two verticals, but may also have high angle lobes from the horizontal wire (effective close-in cloud-warmer)? Yes, above a TOA of about 65 degrees, the radiation is primarily horizontally polarized and there is enough to make some NVIS contacts on the lower bands. You get an interesting pattern if you feed it 1/3 of the way down the horizontal wire. You get some fairly good high angle radiation that can help fill in the nulls in the half-square patternm i,e, the coverage doughnut gets bigger. -- 73, Cecil, W5DXP |
#4
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On Mon, 28 Jul 2003 11:21:12 -0700, W5DXP
wrote: nbr wrote: W5DXP wrote: The center of the "phasing line" on a half-square is a maximum voltage point but there is nothing to keep that horizontal wire from radiating. At a TOA of about 65 degrees the broadside horizontal radiation and vertical radiation of a half-square are about equal at about -9 dBi. I don't think you're suggesting the horizontal component is cancelled out??? So in truth the 1/2-square may perform DX best at low angle TOA broadside to the two verticals, but may also have high angle lobes from the horizontal wire (effective close-in cloud-warmer)? Yes, above a TOA of about 65 degrees, the radiation is primarily horizontally polarized and there is enough to make some NVIS contacts on the lower bands. You get an interesting pattern if you feed it 1/3 of the way down the horizontal wire. You get some fairly good high angle radiation that can help fill in the nulls in the half-square patternm i,e, the coverage doughnut gets bigger. Interesting, I think this could be what happened during our Field Day ops. We worked virtually NO DX, but did decent with this antenna to most parts of the USA. The design of the 1/2-square was "wrong" by conventional design notes, ie the verticals were too long (approx 45' and 65' each) and were separated by WAY too much horizontal (about 130'). If we were radiating low vertical TOA, the propagation wasn't supporting it (or the noise level was too high). However the decent stateside performance suggests we were warming the clouds. Our QTH was mid-USA (Missouri) and broadside to the horizontal wire was E/W; we worked about 40 states. 73 Dan (K0DAN) |
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