mounting omni outside car...weather proofing?

rev_eng · 06-09-2002

im eventually going to mount an omni outside of my car, attached to my roof rack (i have a garvin wilderness rack, and am working on a mount for it)

I have seen some setups with outside antennas, but most are mag-mounted. This will be a fixed-mast, something like the 8 or 9bd one from fab-corp.

The only thing i am really worried about is the weather proofing of it. Does any one have any tips for this? I dont want to have it wired up to just a bare connector, since it will possibly be attached during rain and what not. (i am going to make some sort of quick disconnect for it though)

Will a combination of vinyl and electrical tape, some heat shrink tubing, and some weather-tight disconnects work?

Is there anything im not thinking about?

Thanks for the help

blackwave · 06-09-2002

Quote:

Originally posted by rev_eng

Is there anything im not thinking about?

Hmmm, once you punch a hole through the vehicle surface, you generally use a rubber seal between the antenna base and the vehicle surface. This rubber seal is designed to contract and expand in correlation to the weather. It is that simple and that is all you need to do to weatherproof your antenna. Nothing too difficult or tricky involved.... just remember that once you have punched your hole, you can't go back, (at least without some work on covering the hole and reinitlaizing it's integrity.) so it is best to make sure that the top and the bottom will not interfere with any mechanical parts, or people's appendages.

rev_eng · 06-09-2002

Actually, I already have lights mounted on my rack. I ran the power feed down the factory roofrack runner, and then through a grommet in my tailgate. (its a jeep grand cherokee) All of this is hidden in some small flexible conduit. so no drilling into my roof for me.

I might run the coax down the opposite runner, but would there be a problem running it with the electrical wire? (12vdc, a couple amps)

I would imagine the insulation on the coax would be enough, but i might just do the other side to be safe.

And a run of 15ft should not degrade the signal with decent cable, correct?

Thanks again for the response

lincomatic · 06-09-2002

depends on the cable type. the LMR series cable is very good.
here is an antenuation table. to calc the loss just total up the loss for the type of cable you choose, then add .5dB per connector.

http://www.timesmicrowave.com/cgi-bi...e/LMRGuide.pdf

fungus · 06-11-2002

Use the thickest LMR cable possible and keep it as short as possible. LMR195 or LMR240 in your car (or larger if you have a truck). Make them real short. Have as few connectors as possible. You loose between .5 to 1 dBi with each connector. 15' of LMR195 and you loose almost 3dbi! Shorten it or use thicker cable.

rev_eng · 06-11-2002

I have some LMR400 that im going to use, with a 9dBi omni. Ill let everyone know how it fairs. Im also gathering parts to make my own omni as well (the colinear design floating around)

Thanks again for the help, im sure there will be more questions to come.

fungus · 06-11-2002

I use LMR400 on my WLAN installations. I try to place the AP as close the the antenna as possible.

I've changed the end of one of my Mobile Mark antennas to go directly into an R-SMA on my Zoom 4105 that I use for Kismet. This eliminates the pigtail and I've shortened the cable by a few feet.

If you can connect the cable directly to the antenna and eliminate another connector you'll have some improvment. Anything that can be done to shorten the cable and eliminate connectors makes a big difference.

fungus · 06-11-2002

BTW, here I am setting up a demo 15dBi omni for UNWIRED:

http://cyberverse.lpbn.org:8080/ramgen/UNWIRED060602.rm

Sound is bad. :-(

Check out http://www.lpbn.org UNWIRED for more.

06-09-2002	#1 (permalink)
rev_eng Registered Member Join Date: Jun 2002 Posts: 5	mounting omni outside car...weather proofing? im eventually going to mount an omni outside of my car, attached to my roof rack (i have a garvin wilderness rack, and am working on a mount for it) I have seen some setups with outside antennas, but most are mag-mounted. This will be a fixed-mast, something like the 8 or 9bd one from fab-corp. The only thing i am really worried about is the weather proofing of it. Does any one have any tips for this? I dont want to have it wired up to just a bare connector, since it will possibly be attached during rain and what not. (i am going to make some sort of quick disconnect for it though) Will a combination of vinyl and electrical tape, some heat shrink tubing, and some weather-tight disconnects work? Is there anything im not thinking about? Thanks for the help

06-09-2002	#4 (permalink)
lincomatic Squaaawk! WiFi! WiFi! Join Date: Apr 2002 Location: Tinsel Town Posts: 1,682	depends on the cable type. the LMR series cable is very good. here is an antenuation table. to calc the loss just total up the loss for the type of cable you choose, then add .5dB per connector. http://www.timesmicrowave.com/cgi-bi...e/LMRGuide.pdf __________________ ~lincomatic

06-11-2002	#5 (permalink)
fungus Banned by the masses Join Date: Apr 2002 Location: So. Calif. Posts: 177	Use the thickest LMR cable possible and keep it as short as possible. LMR195 or LMR240 in your car (or larger if you have a truck). Make them real short. Have as few connectors as possible. You loose between .5 to 1 dBi with each connector. 15' of LMR195 and you loose almost 3dbi! Shorten it or use thicker cable. __________________ Work: http://www.wlanparts.com BLOG: http://www.unwiredadventures.com Fun: http://www.socalwug.org

06-11-2002	#7 (permalink)
fungus Banned by the masses Join Date: Apr 2002 Location: So. Calif. Posts: 177	I use LMR400 on my WLAN installations. I try to place the AP as close the the antenna as possible. I've changed the end of one of my Mobile Mark antennas to go directly into an R-SMA on my Zoom 4105 that I use for Kismet. This eliminates the pigtail and I've shortened the cable by a few feet. If you can connect the cable directly to the antenna and eliminate another connector you'll have some improvment. Anything that can be done to shorten the cable and eliminate connectors makes a big difference. __________________ Work: http://www.wlanparts.com BLOG: http://www.unwiredadventures.com Fun: http://www.socalwug.org

06-11-2002	#8 (permalink)
fungus Banned by the masses Join Date: Apr 2002 Location: So. Calif. Posts: 177	BTW, here I am setting up a demo 15dBi omni for UNWIRED: http://cyberverse.lpbn.org:8080/ramgen/UNWIRED060602.rm Sound is bad. :-( Check out http://www.lpbn.org UNWIRED for more. __________________ Work: http://www.wlanparts.com BLOG: http://www.unwiredadventures.com Fun: http://www.socalwug.org

06-09-2002	#3 (permalink)
rev_eng Registered Member Join Date: Jun 2002 Posts: 5	Actually, I already have lights mounted on my rack. I ran the power feed down the factory roofrack runner, and then through a grommet in my tailgate. (its a jeep grand cherokee) All of this is hidden in some small flexible conduit. so no drilling into my roof for me. I might run the coax down the opposite runner, but would there be a problem running it with the electrical wire? (12vdc, a couple amps) I would imagine the insulation on the coax would be enough, but i might just do the other side to be safe. And a run of 15ft should not degrade the signal with decent cable, correct? Thanks again for the response

06-11-2002	#6 (permalink)
rev_eng Registered Member Join Date: Jun 2002 Posts: 5	I have some LMR400 that im going to use, with a 9dBi omni. Ill let everyone know how it fairs. Im also gathering parts to make my own omni as well (the colinear design floating around) Thanks again for the help, im sure there will be more questions to come.

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