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Author Topic: Vertical vs beam  (Read 4654 times)
KC4ZGP
Member

Posts: 1637




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« Reply #15 on: May 26, 2017, 09:12:19 AM »

I vote vertical, omni-directional.

A repeater's coverage is omni-directional.

A beam would block those behind you. You might not hear them and end up interfering.

That's not nice.

73

Kraus
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W8JX
Member

Posts: 12095




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« Reply #16 on: May 26, 2017, 09:54:14 AM »

A typical 5 element yagi will produce about 11dbi gain
and will have a vertical beamwidth of 47degrees

A massive improvement over the High gain fiberglass omni antennas

so yes, beam antennas are the only way to go

I would not be so bold and use the word massive here because real world will be different. First if you mount a 5 element 2m yagi at say 35 feet it is at 35 feet but a say Hustler G7 mounted at 35 feet will extend past 50 feet at top and height helps a lot on this band. Second there is what is known as capture area. As waves travel through space they do not travel evenly on fringes and at extended ranges there is "holes" in coverage. (this can be seen with a HT were moving a few feet can cause a loss of signal at times) A longer/taller antenna spans these gaps and will give you more consistent coverage on FM.
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
AA4PB
Member

Posts: 14360




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« Reply #17 on: May 26, 2017, 12:03:22 PM »

I submit that the holes in coverage seen by moving an HT a few feet are usually caused by multipath. The HT receives the signal by line-of-sight along with a second that is reflected off some distant object. When you move to a position where the two copies of the signal are received 180 deg out of phase and equal strength then the sum signal is zero. Move a short distance one way or the other and the signals no longer cancel. This was demonstrated when I was working with an old wireless mike system in a large auditorium. Move a foot or so one way or the other and the signal would go from full quieting to nothing, even though I could clearly see the receive antenna out in front of me. Modern wireless mike systems generally use multiple receive antennas so that when the signal cancels at one antenna it will still be received by the other antenna just a foot or so away.

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Bob  AA4PB
Garrisonville, VA
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