Roof Mounted Cellular Antennas For Dummies
Continuing on with our “Technology for Dummies” theme let’s cover RV roof penetration and antenna mounting for cellula modem/routers. Penetration of the roof seems to be the big hangup for folks wanting to move to better digital cellular technology. For fringe applications you definitely need a roof mounted antenna to get the best out of the system. The whole point of these systems is to improve data reception in fringe conditions. Leaving out a good external antenna makes no sense when you consider the investment. I covered the equipment needed for this new technology in another thread “Best RV Internet for Dummies
” but did not spend a lot of time talking about the installation of a roof mounted antenna.
There seems to be an unreasonable fear by owners about penetrating the roof of their coach. What’s the worse that can happen? If you put a small hole in the roof looking for a path that does not pan out to pass antenna cables, you just cap it and slobber on some Dicor
and move on. Nobody will see it and if you do it right it will not leak.
Every RV roof is different, so there is no cookbook approach to mounting a roof top antenna on an RV but let me walk you through the basics that I used for my New Aire.
Step 1 - Site Survey
This is the most important step to install a modem/router with an external antenna. You need to find a location inside the RV, near the ceiling with 12 volt power available. Preferably you want that power unswitched by the house battery switch so that your modem/router is always on. With an always on modem/router you can then support a variety ofIOT
devices to check on your coach (ie cameras, weather station, MyRozie, Insteon etc). For those coaches with SilverLeaf MyRozie, the location also has to be near the ethernet cable connected to the MyRozie module. In Newmar coaches this is typically an overhead cabinet near the driver’s seat.
Next you need to survey the roof immediately above the cabinet to place the antenna. You need to place the antenna nominally within 3 feet of the modem/router. You want to keep the antenna leads as short as possible for the best performance. If the antenna you pick has leads longer than 3 feet plan to trim those leads with new SMA connectors (male
You want to mount the MIMO antenna on the roof as far away as possible from other antennas, particularly OTA TV antennas. WiFi and Cellular radios will destroy OTA TV reception.
You want the MIMO antenna to have a 360 degree view of the horizon when mounted on the roof. High frequency cellular is primarily line of sight. If there are any objects between the antenna and the cell site the signal will be attenuated to some degree. The antenna should be mounted with 3M double sided tape and Dicor covering the tape so that can be easily removed or to allow the antenna to break free if hit by branch without damaging anything. High mounted RV antennas need to be looked as a consumable. You will likely nock it off someday, that’s why the invented double sided tape.
Lastly you may have to build a antenna mount to get it in the best position. I have found aluminum stock from Home Depot to be the best material to craft a home made antenna mount. It does not have to be pretty. Nobody will see it on the roof.
Step 2 - Penetration and Exploration
So you have now scoped out the project. Now you need to find a path from the antenna location to the location where you will put the modem/router. This is the fun part. High anxiety. There are many ways to approach roof penetration and exploration.
You will need a wireless WiFi endoscope
. There are cheap and available for $35 on Amazon.
In my New Aire I started my roof exploration by pulling the nearest ceiling LED light to the cabinet where the modem/router would go. With the light hanging out of the hole you have more than enough room to explore the cavity between the ceiling and the roof. Stick your new endoscope through the hole and start looking around. It will take some time to get proficient doing endoscopic exploring because it is easy to get disoriented not knowing what is up/down and right/left as you move the endoscope head around overhead. Keep working with it in and no time you will become familiar with the cavity and how to manipulate the scope.
You will probably have to move some insulation aside here and there to see things. In my case once I moved the insulation aside I could immediately view the under side of the roof and associated structure with the endoscope so I quickly found a place to penetrate the roof just 18" above the ceiling LED light.
Next I moved on to explore the path through the cavity from the proposed roof penetration to the cabinet. In the New Aire this was the biggest challenge. Newmar constructs the front cap of the coach in such a way that it brings a fiberglass shelf right over the top of the cabinet above the driver’s seat with a space above that shelf before you see the actual external front cap surface. So I could pass the endoscope forward to a space just above the front cabinet between the front cap surface and the fiberglass shelf below.
The next step was the hardest part of the installation. With the endoscope in place visualizing the space above the cabinet I used a one inch hole saw with a 90 degree drill bit adapter to go up through the top of the cabinet then penetrating the fiberglass shelf. Once I broke through the self I could see the hole saw emerge above the shelf with the endoscope. This is very important so that you don’t continue with the hole saw all the way through the front cap of the coach to the outside.
Step 3 - Passing the Antenna Cables
Ok, step 2 was the hard part. If you don’t have a New Aire you may find a different situation above the cabinet but you can see the process with my New Aire description. With the cabinet hold drilled to the space above the cabinet, you are ready for the roof. Just use the same 1” or 1 1/2” hole saw to drill out a core from the fiberglass roof. The hole only has to be big enough to pass 4 or 5 RG59 cables from the antenna.
Once that hole is drilled attach a strong string to the end of the endoscope and run the endoscope from the roof hole to the cabinet hole previously drilled. I did this in two steps. First I ran the endoscope from the hole on the roof through the ceiling mounted LED hole then pulled the string through then withdrawing the endoscope. Second I attached the string to the endoscope again at the LED ceiling light hole then passed the endoscope forward and down through the hole in the top of the cabinet. Once done I had a string from the roof to the cabinet.
Next attach the antenna leads to the string on the roof and pull the leads through the space above the ceiling into and through the hole in the top of the cabinet.
Step 4 - Mounting the Antenna
This step is up to you depending on roof and antenna configuration as described in the introduction.
Step 5 - Trimming the Antenna Leads
This is an optional step. If the antenna you select has very long leads you need to trim the excess and install new SMA fittings to avoid unnecessary signal loss in the antenna leads. You will need two SMA male and two SMA female fittings and an SMA crimp tool
for this step.
If you think you might move on to a dual modem configuration in the future I recommend you pull additional RG59 cables. 4X4 MIMO is coming so future applications will be use 4 RG59 cables for the cellular modem and 2 RG59 for WiFi. You also might want pull an ethernet cable. Future cellular modems will likely be integral antenna/modem combination driven by a POE ethernet
connection. When this happens all these antenna cables will be surplus. There will just be a single ethernet cable running from the roof to the inside of the coach.