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VHF antenna?


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I was just wondering, for my ham radio, would a 8' marine antenna like I use on my boat work or is that not the right sort of antenna?
 I already have one of those that I bought for my boat, but never installed, then I sold the boat.  If that would work then it'd save me from having to buy another antenna.
Here's the specs

Thanks in advance

Anthony

 

antenna.JPG

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ELMER

Hi Anthony, me again 😎

Way too long (I'll never admit I typed that). VHF is 144 to 148 Mhz which equals ±2 meters which equals ±6-½ feet. So your 8-foot antenna is actually longer than a full wavelength at 2 meters. When you think antenna, the first thing to think of is length. There is obviously much much more to an antenna than just its length, but that's where the calculation begins. For now I won't make recommendations on options, because I would need to know more, but an 8-footer marine antenna is wrong for 2 meters. Also, not sure where the got that 6 db gain? That's a lot of gain for what seems an omni, or is it directional? Hmm.

  1. Is this for home or car?
  2. Will you mount inside or outside?
  3. Ground, wall or roof?
  4. Assume that you want both 2 meters and 70 cm!
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Posted (edited)

Thank you Jim.

I was considering if I could use it for my home base antenna.  But your explanation makes sense.  Yes I'd like both 2m and 70cm but right now I'd take whatever I can get.  I don't know about the 6db gain.  You're talking outside my knowledge level.  🙂


Anthony

Edited by KO4QDG
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ELMER

How do you plan on mounting the antenna?

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ELMER

Anthony, there are thousands of good antennas for a rooftop install. Every ham will give you a different option. I will do the same and give you my all-time favorite omni VHF/UHF antenna, the J-Pole and its cousin the Slim Jim. I have a preferred supplier:

Which one you get will depend on mounting height. Here is the quote from his website:

Quote

Both the Slim Jim and J-Pole are great antennas and I continue to recommend both styles of antennas for different situations. The J-Pole will excel at lower mounting heights, apartments, or limited space locations. It’s 20 degree takeoff angle makes it a great choice for people living in valleys or the base of mountain ranges. It’s even radiation pattern is great for communicating with satellites and the International Space Station.

The Slim Jim likes to be mounted high. My experience with it is that you want to get this antenna up at least 20 or 30 feet for it to really perform. The lower takeoff angle is great for simplex communications with handheld or mobile radios. The low noise floor is perfect for data and packet stations. If you live on the top of a hill, go for the Slim Jim.

For a chimney, I would get the Slim Jim, of course 😎

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Posted (edited)

Yes Sir!

That's the one I was looking at.  I just wanted to wait until I got my radio.  I was going to order it last week, but I saw there's a few options for the type of connector and I didn't want to order it then find out my radio had a different antenna jack than the antenna I ordered.

That's so odd, at least to someone ignorant like me, that a piece of copper tubing will be such a good antenna.

I got my radio today (more powerful than my Baofeng HT), now I just have to figure out how to work it.

NewRadioMay2021.jpg

Edited by KO4QDG
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ELMER

Copper rules!! Congratulations on the radio!

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You may have problems. I looked up the antenna on the manufacturer's website and it indicates that the low end of the frequency range is 156 MHz. I would assume that the length is a result of some kind of colinear setup stacking several antennas one above the other to give you the 6db gain.

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ELMER
9 hours ago, WA2WMR said:

You may have problems. I looked up the antenna on the manufacturer's website and it indicates that the low end of the frequency range is 156 MHz. I would assume that the length is a result of some kind of colinear setup stacking several antennas one above the other to give you the 6db gain.

Sorry Lind, which antenna are you referring to? The KB9VBR J-Pole? 'Cause that one is spot on. Or are you referring to the Marine antenna Anthony mentioned at the start of the thread?

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