FEM: Field-Expedient Mesh

Overview

The Field-Expedient Mesh (“FEM”) is a portable deployable Amateur Radio Emergency Digital Network (“AREDN”) wireless Mobile Ad-hoc Network (“MANET”).

FEM can either initiate a local MANET, or extend/augment an existing MANET, particularly in emergent situations, or into areas where MANET coverage might not already exist. It is designed to operate independently of shore-power or existing infrastructure of any kind, and is assembled with Commercial Off The Shelf (“COTS”) components. Once installed into an area that receives sufficient daytime sunlight, FEM should operate unattended for an indefinite period.

Because FEM is made up of COTS components, its cost is relatively low, and its constituent parts are commonly found and interchangeable between vendors.

High-Level Components

1. Power:

1. Solar Panel
2. Battery & Battery Charge Controller
3. DC Power Adapter

2. Radio:

1. Wireless MANET Radio
2. Antenna

3. Mast.
4. Enclosure.

Bill of Materials (BOM) [~$850]

• Ubiquiti airMAX Rocket M5 BaseStation ($89): https://www.ui.com/airmax/rocketm/

• Running the AREDN Mesh firmware: https://www.arednmesh.org/

• Ubiquiti airMAX Omni 5 GHz, 10 dBi Antenna ($125): https://store.ui.com/collections/operator-airmax-and-ltu-antennas/products/5ghz-airmax-omni-10dbi-rocket-kit
• AmazonBasics Lighting Stand ($33): https://www.amazon.com/dp/B074VMTP68
• Passive PoE Injector ($7): https://www.amazon.com/dp/B00NRHNPUA
• GoalZero Sherpa 100 Power Bank: Discontinued, see Assembly Notes.
• GoalZero Nomad 20 Solar Panel: Discontinued, see Assembly Notes.
• 7 Foot (2 Meter) Ethernet Cable (MP).
• “Ammo” or “Pelican” rugged weather-resistant case (MP).

Assembly Instructions

1. Attach the Omni Antenna to the Lighting Stand.
2. Connect the Rocket M5 to the Omni Antenna.
3. Connect one end of the Ethernet cable to the Rocket M5.
4. Connect the opposite end of the Ethernet cable to the Passive PoE Injector.
5. Connect the Passive PoE Injector to the DC Barrel Adapter.
6. Connect the DC Barrel Adapter to the GoalZero DC “Car Accessory” Adapter.
7. Connect the GoalZero “Car Accessory” Adapter to the GoalZero’s 12 VDC output port.
8. Power-on the GoalZero.
9. Attach the Solar Panel to the GoalZero.
10. Enjoy your new Mesh Network!

Assembly Notes

• The GoalZero Sherpa 100 Power Bank used in the initial design has since been discontinued and replaced with the Sherpa 100AC Power Bank. The Sherpa 100AC (and smaller 100PD) provide USB-C Power Distribution (USB-C PD) outputs, which can be used to power a Rocket M5, but require a completely different DC Power Delivery subsystem, which is beyond the scope of this document at this time.
• The GoalZero Nomad 20 Solar Panel used in the initial design has since been discontinued and replaced with the Nomad 50 ($250): https://www.goalzero.com/shop/solar-chargers/nomad-50w-solar-panel/
• The Rocket M5 is designed to operate between 8 VDC and 24 VDC. The 12 VDC output from the Sherpa 100 is sufficient to operate a Rocket M5 at full power with a 850 mAh load.
• Consider a small bag to store the DC Power Adapters used in the FEM.
• Consider using the GoalZero as a counter-weight/ballast for the lighting stand in high-wind weather conditions.
• Bring spare fuses for the GoalZero.
• TBD: The “PoE-Barrel-Car Accessor-GoalZero” DC Power Delivery Subsystem could be simplified, for example, a “PoE-GoalZero” chain.

System Diagrams