Roof Mounted Cellular Antennas For Dummies

[turbopilot]

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 and female).

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.

[Isaac-1]

If you want to get decent performance you really should get a no ground plane model, most of the small ones and all the magnetic mount antennas are ground plane models and expect to be mounted on a steel roof which it uses for its reference ground plane (sort of a reflector) Most motorhomes have synthetic or Aluminum roofs which do not provide a good ground plane reflection, one such antenna is the Wilson Truckers antenna as it is designed to mount above a fiberglass truck cab. See https://smile.amazon.com/gp/offer-listing/B01FUF1JAY/

[turbopilot]

Originally Posted by Isaac-1

If you want to get decent performance you really should get a no ground plane model, most of the small ones and all the magnetic mount antennas are ground plane models and expect to be mounted on a steel roof which it uses for its reference ground plane (sort of a reflector) Most motorhomes have synthetic or Aluminum roofs which do not provide a good ground plane reflection, one such antenna is the Wilson Truckers antenna as it is designed to mount above a fiberglass truck cab. See https://smile.amazon.com/gp/offer-listing/B01FUF1JAY/

This subject has been covered in previous posts. Neither antenna recommended needs a ground plane by design.

[tnedator]

You have the raised front cap to help shield your antenna/mount from the wind.

On a Ventana with no raised cap/facade, do you think 3M tape is strong enough for the wind force not only on the antenna but the mount?

[BuckyII]

Turbo, I hear you...”if you’re going to do it, do it right!”

Thanks again for the advice AND the detailed instructions. Lots of food for thought...will visit coach and check things out.

Did you use the GPS connection on the antenna to run a new cable to the Navigation unit?

[TDL]

I’ve had my MIMO antenna on my Ventana for 4 years using 3M tape and a bead of Dicor. All’s well!

TDL

[turbopilot]

Originally Posted by tnedator

You have the raised front cap to help shield your antenna/mount from the wind.

On a Ventana with no raised cap/facade, do you think 3M tape is strong enough for the wind force not only on the antenna but the mount?

I think there is an aerodynamic dead spot just aft of the front cap at high speeds owing to the hugh flat plate of the front mask hitting a 65 mph wind. If your worried mock something up and stick it to the roof and go drive fast to see how it does.

[turbopilot]

Originally Posted by BuckyII

Did you use the GPS connection on the antenna to run a new cable to the Navigation unit?

I don't. I have other ways to get GPS position data. That functionality on the PepWave/Cradlepoint is for fleet tracking which you have to pay for after the one year warranty.

[turbopilot]

Originally Posted by BuckyII

Turbo, I hear you...”if you’re going to do it, do it right!”

Thanks again for the advice AND the detailed instructions. Lots of food for thought...will visit coach and check things out.

I think the front mask area on the NA3341 is identical to my 3343. You should be able to follow my instructions exactly. MyRozie ethernet cable terminates in the cabinet above and the 12 volt line coming into cabinet for the WiFiRanger is unswiitched (except for the WiFi switch) and handles all my equipment. If you are going to do this run spare ethernet cable to roof as well. My guess is some one will be announcing an integral CAT 18 modem/antenna soon (below $1,000) with POE power which means you can pull out all the antenna cable and antenna when that product comes.

[YC1]

Having done thousands of installations personally and tens of thousands in my shops over 40 years I would like to commend you on your exceptionally well written and illustrated report.

The advent of bore scopes has decreased the blood pressure a bit over the years. Drilling through a roof is always a bit of hand wringing on a new vehicle.

To add one suggestion if using an NMO mount, "Motorola mount". You can use a hole saw to cut a 1.5 to 2 inch hole in a thick roof. Install the mount on a piece of either galvanized tin or aluminum plate of the proper thickness. Once you have things assembled you can then drop this plate over the hole using the proper sealant beneath the nice mount/ground plane. If you have the need for multiple antennas you can spread the metal over a larger area and place your antennas on it. It is easier to do than explain without the talent of the OP writer.

It might be fun to start another post and have folks post pictures of their specialized tools. I have a monster magnet that looks like a narrow paint roller. It is so powerful I have to be very careful to not cause an injury. It can pull leaders through roofs in places fish rods and tapes don't work. Often you have to pull out all of your tricks to get the cables run. And all of this while trying to NOT punch a hole in some wires or pipes.

[turbopilot]

A small illustrative story about this issue of internal versus external antenna placement for cellular modems. I have a house in the country on the central coast of California. The only wired internet service I can get here is a DSL modem with 5Mbps down and .6 Mbps up. Not enough for me. I have used various WiFi services available locally. They are faster but expensive and more unreliable than the DSL. They also are very oversubscribed at peak demand.

So I have been experimenting with an old PepWave MAX-BR1-LTE-US at the house removed from my last RV. This is an old CAT 4 modem device. It has 2X2 MIMO but no LTE-A. My plan was to use this device to manage a cellular data connection using (using a $20/month SIM on my Unlimited Verizon plan) as a back up to the internet provided by the DSL modem. This will allow my security system to be up all the time. The home security system is entirely internet based and the DSL modem at the house has not been reliable. I am 4 miles from the nearest cell tower in a area with big hills. The wireless cellular signal is not great, so the challenge was to get a good cellular signal.

The last thing I wanted to do at the house is install an external cellular antenna. See the irony?

I got the entire system installed and it was working as planned except I could only get around 2 to 3 Mpbs down on the old PepWave MAX-BR1-LTE-US with the rabbit ears. So I started a journey moving the system from room to roof around the house looking for a little better signal.

Just for grins I put the PepWave up high in a back closet and did a speed test. Here is the result. This result is rabbit ears only, off peak time.



Yes, I know this whole story plays right into Neil's position about the need for external antennas. But remember it literally took me weeks to find this small area of quality reception in the house. The same thing will happen in an RV. You can put the CradlePoint on the counter inside the coach with rabbit ears and get 40 Mbps down. Then if you simply turn the RV 180 degrees away from the cell tower the speed may drop below 5 Mbps. These high frequency radio waves are just unpredictable.

Ok. This is not the end of this story. After I got this whole system set up I went down to the Verizon store and picked up a SIM for the "unadvertised" prepaid unlimited $65/month data plan. That speed test above is from that plan running on the CradlePoint CAT 4 modem with rabbit ears!

So now my "backup" cellular data connection has become my primary household internet source. Yes, the prepaid Unlimited data plan is throttled at peak demand. I am finding it tends to throttle at about 50% of the speed from my post paid SIM running on my regular Verizon Unlimited account but still much faster than the DSL. I have both the postpaid and prepaid SIM loaded in the PepWave SIM slots so I can switch back and forth. The neat thing is that now I can pull the prepaid SIM from house setup leaving the house Cradlepoint to back up the DSL with the $20/mo post paid SIM and take the prepaid SIM to the coach and use it when I am on the road. $65/mo very well spent.

So the story is complicated when it comes to the need for external antennas. Neil is right you can get very good speeds without an external antenna. The question is how much fiddling around do you want to do every time you park the coach to find the peak signal.

[Johninar]

Great write up.Thanks for taking the time to do this.

Measure twice, drill once. LOL

[tnedator]

How do you get the LED lights out. Is it just a pressure fit or are they screwed in?

[redbaron73]

Originally Posted by tnedator

How do you get the LED lights out. Is it just a pressure fit or are they screwed in?

Pull from one side and they snap out. Clips on the perimeter. Mine had two clips