Radio Frequency (RF) & Wireless Design

I was researching some of the drone UAV / Quadcopter / Multi-copter Wireless (Telemetry) Communication Links frequencies to see what was available and came across the APM 2.6 module which lead me to their telemetry options landing page :

https://ardupilot.org/copter/docs/common-telemetry-landingpage.html#common-telemetry-landingpage

In reviewing all of these I was able to 'boil down' these types of wireless communication protocols and their typical maximum distance at 100 mW of output power and clear line of sight using an omnidirectional monopole antenna with 2.15 dBi of gain:

• Bluetooth (up to 100m with Class 1)
• Wi-Fi (up to 100m at 2.4 GHz and 50m at 5.6 GHz)
• Wi-Fi 4 using MIMO (up to 200m at 2.4 GHz and 100m at 5.6 GHz)
• ISM (Industrial-Scientific-Medical) 900 MHz UHF Band (up to 2 Km)
• 4G / WiMax cellular (up to 4 Km)
• 5G cellular (up to 1 Km at 5.6 GHz)

Also all distances are nominalized using the same data rate, but since lower frequency bands typically handle lower data rates, they are able to handle longer distances using the same output power.

However, for First Person Video (FPV) control where the data is much higher and streaming real-time, distances can be much shorter before the data stream starts to fragment and frame error loss increases logarithmically.

So when considering your wireless link to your drone, you must consider these usage model criterion to balance your choices :

• output power
• antenna gain
• frequency band
• data rate
• elevation
• operating time

One of the best ways to increase range, especially for higher data rates and to reduce power (longer flight times) is to use a MIMO multiple antenna approach. Another is to use a extremely high gain antenna, and finally the best way is to use a directional tracking antenna.

Each of these adds a higher level of complexity as well as increased costs, but for top performance each must be weighed carefully.