A linear actuator is used to stow and deploy a small RV rooftop antenna array. This keeps sensitive rooftop equipment out of harms way. Antennas inside an RV can still work but with limited effectiveness. Mounted on top of the RV, the antenna array gives the communications system greater range for the LTE cellular and Wifi networks.
As an Amazon Associate, at no additional cost to you I earn from qualifying purchases. If you don’t see Amazon product images on this page, or the ads seem incomplete, click here.
About The Antenna Stow-Deploy System
It’s purpose is to deploy and stow an antenna array for Internet and Wifi communications. The system has enough capacity to accommodate video cameras or other accessories in the future. The system is sub-component that fits tightly between the solar panels and in-between the two roof fans, on the roof rack. The current antennas increase the RV height by 18”, to a total hight of about 11’ 6”. At the current hight of 10’ we often brush low hanging branches.
Tip: Use 30 second glue (link below) to set parts in place while making adjustments. If necessary you can separate parts, re-sand and re-glue. Clamps are good too, when they don’t get in the way.
RV Roof Placement
Design Basics
The sub-system, when installed fits perfectly between the two rows of solar panels, and between two cross rails. First make the sub-system rack fit where it needs to be installed, with a little (1/4”) leeway. This way you can move it to your workbench while avoiding all the up/down time and travel your RV roof.
The frame is made from lightweight 3/4” tube aluminum, and the fasteners are corrosion resistant stainless steel. The linear actuator completes a 50 mm movement in about 1 second, converting linear motion to 90 degree rotational motion. The linear actuator is quiet at less than 45 decibels, it operates on 12 volts DC, and at temperatures from -25 to +65 degrees C.
Bench test test everything. You don’t want to waste time installing antennas that don’t work in your situation. It is important to test the specific cables and connectors that you will be using too.
In this early video, the hinge is held in place with glue and other parts with a clamp and rubber band. Ideally your design will have adjustment capability. Aluminum is relatively easy to work with, use basic woodworking tools and safety precautions. Be sure to protect your eyes, ears and hands. Sometimes I wear a full face mask.
Design Deficiencies
Eventually all systems fail, but how will it fail? Looking at the design, materials and project execution, it could go quite some time before failure. Linear actuators are generally rated at 5,000 to 20,000 hours. 5000 hours at 6 hours sunlight per day amounts to 2.28 years before failing. When it does fail, it is likely due to an unforeseen natural event such as lightning or physical damage from an arial obstruction. Additionally, there are a few plastic parts on the edge of the actuator as well as the cabling and connections that are subject to ultra-violet light. There is the obvious scenario that operator error or computer logic error can deploy the antenna array at an inappropriate time.
What V2.0 Features Are Under Consideration
The linear actuator is very powerful at 100 newtons of force. With this amount of leverage, much larger arrays of antennas or video cameras can be stowed and deployed. Secondly, the double-pole stow-deploy switch can be controlled with a double-pole relay for automation control. A sensor can be added to provide close-loop feedback on the state of articulation.
Linear Actuator Force & Load Considerations
This linear actuator produces about 100 newtons of force. One Newton is approximately the force of Earth’s gravity on an apple. A 100N load capacity is roughly equivalent to the gravitational force on 100 apples. However, it’s essential to understand that “load capacity” doesn’t directly translate to weight, even though they are related. The weight of an object is the force exerted on it due to gravity, and it’s measured in Newtons, or pounds, kilograms, etc.. If you’re trying to determine how much weight in terms of mass, a system with a 100N load capacity can support on Earth, you’d use the formula: Weight (N) = mass (kg) × gravitational acceleration (m/s squared) On Earth, we take the weight of 100 apples and divide it by 9.81 meters per second squared, resulting in approximately 10.2 kg or about 22 US pounds.
This describes the linear actuator, but our design converts a linear force into a rotational force. The the linear force is used to drive two rotating antenna support rails through 90 degrees of motion. The impulse force at the beginning of the rotation will be substantial. At least for V1.0, it appears to handle the current antenna array with ease. If someone with solid mechanical engineering acumen has good math on this, I would appreciate hearing from you in the comment section. For now, lets not put a bushel basket of apples directly on the rotating surfaces.
Wifi Bench-Test Performance, TP-Link EAP225
The standard Wifi antennas of the Teltonika RUTX11 provides a minimally functional Wifi signal at 90 feet. This is fine when you are next to the RV, but what if you are nearby in a coffee shop, at a music festival, or hanging out around a neighbors campfire. The 300+ feet range of the TP-Link EAP225-Outdoor is a game changer. It allows direct connection to the RV without having to use the Internet or local Intranet infrastructure. Your cell phone can notify you if the RV batteries are getting low, or are fully charged, or there is an intruder in your RV. Not only does it save money by not using the Internet, we are frequently in places where there is no Internet.
About antennas, two of the largest sources of noise (interference), are cables and connectors. Good cables are thick, stuff and difficult to work with, as well as expensive. Connectors are also prone to issues, corrosion and in general trouble. Combine this with the vibrations of the rolling RV-earthquake, it is not if there will be problems, but when.
Antennas of the style of the TP-Link EAP225 have a different approach. The antennas are mounted directly to the unit, eliminating all but a short internal cable. A Power Over Internet (POI) cable provides both power and network connectivity to the device. This is a good, cost-effective antenna with an Amazon Affiliate link provided below.
| Distance (ft) | Frequency | Download Speed |
|---|---|---|
| 300 | 2.4 ghz | 3.6 Mbps |
| 300 | 5.0 ghz | 4.7 Mbps |
| 240 | 2.4 ghz | 16 Mbps |
| 240 | 5.0 ghz | 22 Mbps |
| 90 | 2.4 ghz | 30 Mbps |
| 90 | 5.0 ghz | 31 Mbps |
More Information
You can find more information on the Ford Transit RV build at https://diyrvforum.com/tag/ford-transit
Here is an article on the RV Computer Network https://makermattdesign.com/posts/rv-network/
The Maker Matt Design YouTube channel is https://www.youtube.com/@makermattdesign