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Author Topic: Dual Band Antenna In A Camper van  (Read 394 times)
KC5MNG
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Posts: 6




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« on: January 19, 2006, 05:59:16 AM »

I have contacted several sources about this and have received a variety of answers. The retail guys say it can be done using THEIR parts and just want to make a sale.. The antenna makers won't say much because it would be using their product under less than optimum conditions, so here I am, asking the guys in the know. BTW, I'm returning to ham radio after a several year absence and this is my first dual-band VHF mobil installation in some time.

My question is on antenna placement. I have a Ford extended wheelbase van that I'm converting to a camper, and I just had a hard fiberglass raised roof installed. The way it was installed was by removing part of the van's steel roof. The portion of the original steel roof over the driver/passenger area was left in place over the driver/passenger area for support, then the raise roof was set in place.So there is a ramaining steel shelf with about 20" of vertical space. So, my question is... Can I install a roof mount antenna to the remaining portion of the steel roof, using the rest of the van's body for a ground plane without being greatly affected by the fiberglass roof? It's effectively a roof antenna covered by a fiberglass bubble. This also assuming there is a whip that is short enough to fit, so how about antenna suggestions here.I'd also like to use that area for storage of non-reflective type soft items such as clothing and bedding, etc. Should that have any adverse effect?

If this isn't the best way to install the antenna, I'm open to suggestions. I'm not too keen about drilling exterior holes in the van or the top, but I would if that's the only way to do it. Are there any other possibilities. As far as using an exterior antenna, I'm receptive to that, but the height of the van with the new roof is already around 9 feet, so I really don't care to have anything very much higher than the roof top. I know that most of the antenna needs to be above the body of the vehicle, but I don't know if that applies only to steel bodies, or to the fiberglass top as well.

Any suggestions would be very much appreciated.

Bob Landry
KC5MNG
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W3LK
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Posts: 5639




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« Reply #1 on: January 19, 2006, 08:14:18 AM »

Bob:

<< So, my question is... Can I install a roof mount antenna to the remaining portion of the steel roof, using the rest of the van's body for a ground plane without being greatly affected by the fiberglass roof? >>

Yes! You get about the same effect as people mounting antenns on trunk lids. The only real ground plane you will have is what is directly under the antenna as a flat surface. The rest of the body will have little, if any, effect on the antenna.

As for antennas - the Larsen NMO240 or 240B mounted using a properly installed NMO mount.

Go to www.k0bg.com and look over the information there. Alan's web site is a gold mine of mobile installation information.

73,

Lon
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KE4SKY
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« Reply #2 on: January 20, 2006, 05:06:08 AM »

This sounds similar to an install on a fiberglass ambulance cab.  The cab roof has enough ground plane to work fine on VHF and UHF.  The fiberglass shell won't cause any problem as long as you don't use metalflake paint on it.

Remove the interior dome light panel inside the cab in the center roof headliner, carefully pull out the light fixture and spot the hole through the roof at this location to install the NMO through the roof.

Get a sturdy, cheap and simple dual-band, quarter-wave whip.  I'd get a commercial grade one such as Antenna Specialists or Antennex. Use a fish tape to work the coax down the driver's side doorpost and under the floor matting to the rig and then reinstall the ceiling dome light.  
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WA4CCH
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Posts: 48




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« Reply #3 on: January 23, 2006, 12:57:32 PM »

hi what i would like to know how much did it cost to put the shell on top been thinking about doing it to my one ton dodge van

thanks chuck

if you want you may answer via regular e-mail
wa4cch at hotmail.com
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