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Commercial Radio Antennas - Please keep discussion related to professional, commercially used antennas and antenna systems for the two-way radio industry. Topics for the use of these antennas on amateur bands are accepted here.

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Old 11-04-2017, 1:13 PM
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Default Telewave ANT150F2-No way 60 inches

Among the antennas I am considering to install is the Telewave ANT150F2. My problem is how could a collinear at these frequencies be only 60 inches long? Using the shortest length frequency-174, two half-wave elements work out to 64 and 1/2 inches and this does not even include element spacing. It defies physics. Is this published length of 60 inches a misprint? Is there a new collinear technology out there that I am not aware of? Serious question. Is Telewave lying? Telewave is usually pretty truthful about their antenna specs.
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Old 11-04-2017, 1:26 PM
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Do you have a link to it?
Is this a VHF only antenna or is it available in different bands? Maybe the dimensions are wrong.
If it's really just a VHF dipole antenna it could easily be 60 inches or less.
If it's really a collinear made from transmission line sections then you have to take into account the velocity factor of the transmission line. The electrical length of the elements could be about 2/3 the size of the free space length. Also there is no element spacing on one of those, the elements are connected together.
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Old 11-04-2017, 1:36 PM
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Have not figured out how to hotlink yet. Still fairly new at this RR thingy. But here is the link-https://www.telewave.com/product/ant150f2-omnidirectional-collinear-antenna-148-174mhz/. Says VHF only and collinear.
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Old 11-07-2017, 8:04 PM
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Nd5y hit the nail squarely on the head
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Old 11-07-2017, 9:33 PM
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Look at the VSWR plot. You'll see some variation in the baseline. The VSWR remains fairly low, but what you might notice is that as frequency changes, the phasing - and subsequently the electrical tilt - will change directing the major lobe either upward away from the horizon or downward. It can be fairly broadband nonetheless. This is probably a 5/8 over a 5/8 element at the center frequency.
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Old 11-07-2017, 10:31 PM
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So this is possibly a 1/2 over 1/2 or a 5/8 over 5/8 with a transmission line shortened because of the velocity factor? No spacing is required? I just never heard of that. Well, you live and learn.
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Old 11-08-2017, 12:48 AM
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I've opened a lot of antennas and have only seen the half wavelength in coax collinears in 5dBd size and up. Smaller ones are usually 1/2 or 5/8 wave elements made of wire with a pig tail or folded phasing coil.

I think 60in is too short for a half wave in coax or wire element type of collinear at VHF. The coax element types are a bit shorter but you usually have a 1/4 wave spike on top and a 1/4 wave decoupling section at the bottom, which woudl be much longer than 60in. A stacked 1/2 over 1/2 wave with phasing coil in wire would also be more than 60in long at VHF. The collinear description must be a typo.
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Old 11-08-2017, 11:36 AM
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Yeah prc, my thinking was kind of along the same lines as yours. The collinear description, dbd figure or length must be a typo. But apparently others above say it is possible. Gee, so who am I to believe?
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Old 11-08-2017, 12:01 PM
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I often buy an antenna to cut it open and dissect. Maybe someone has a Telewave they want to cannibalize?
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Quote:
Originally Posted by Lowboy23 View Post
Yeah prc, my thinking was kind of along the same lines as yours. The collinear description, dbd figure or length must be a typo. But apparently others above say it is possible. Gee, so who am I to believe?
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Old 11-08-2017, 12:26 PM
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Like what most antenna manufacturers do, it's on a platform of colinear antennas but it's gain characteristics are that of a 5/8 wave. Could be a 1/4 over 1/2 but I don't know how well that would work out.
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Old 11-26-2017, 8:52 PM
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I have an ANT150 on a site that was primary for a year on a public safety channel but was put into backup service when a 4-bay dipole was installed. It was a decent antenna and it was chosen because of its size, gain and semi-wide band performance. A 2-bay dipole was a tad bit better in my opinion (at th same site) then the ANT150 , but for the size and needs at the time, it was a good choice.

Have seen a local LMR installer lately using them as well for some low level commercial repeater sites and he has mentioned they are doing well and stealthiness of them.
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