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In search and rescue, locating a person can be only half the problem.

They may be in a ravine, behind a ridge or in mountainous terrain without cellular coverage. Even the rescue team's radios may be unable to establish a direct link. The landscape itself becomes a communication barrier.

What if, instead of overcoming that barrier from the ground, we raised the communication infrastructure into the air?

That is the idea we are exploring: a drone acting as a temporary radio repeater—and, if needed, bringing a communication device to the person on the ground.

The problem: two people, two radios, no contact

In many radio systems, particularly VHF and UHF links, terrain and line of sight affect communication. Visual line of sight alone does not guarantee a working radio link.

Teams only a few kilometres apart may be separated by a ridge, canyon or large structure that substantially weakens their direct connection. In a rescue operation, that can mean:

  • A ground team unable to reach incident command.
  • A located person without a suitable communication device.
  • Teams working on opposite sides of a ridge.
  • An area without cellular infrastructure.
  • An incident that has damaged the local communication network.

Instead of installing a fixed repeater on a mountain, a suitably equipped drone could place a temporary relay where it is needed.

The idea: Drone as an Airborne Radio Repeater

The drone carries a compact communication payload containing a radio repeater and antennas. It moves to a position with better radio visibility to the two areas and relays traffic between compatible radios.

Ground team A → radio → airborne drone repeater → radio → ground team B

Here, the aircraft is more than a camera. It becomes temporary communication infrastructure.

Taking the concept one step further

Imagine that a drone locates an injured walker in a ravine. Rescuers know where the person is, but the person has no working phone, no cellular coverage and no compatible radio.

In the proposed concept, an adapted drone could bring a compact communication unit to them. Safe delivery and integration with the repeater still require development and testing.

Step 1 — Locate

The person is located using a conventional camera, a thermal camera or information supplied by search teams.

Step 2 — Deliver

A communication pod is lowered using a controlled mechanism at an assessed delivery point near the person. Flying or lowering a load directly above someone must not be assumed safe.

The proposed pod could contain:

  • A speaker and microphone.
  • A large push-to-talk button.
  • Its own battery.
  • Optional GPS.
  • Simple operating instructions.

The aim is to avoid asking the recipient to configure frequencies, channels or radio settings: they receive a prepared device and press a button to speak.

Step 3 — Climb

After delivery, the drone returns to a suitable relay position. It no longer needs to remain beside the person; it needs a position that supports the radio links.

Step 4 — Relay

Person on the ground → delivered radio → drone repeater → rescue team

If the links and equipment work as intended, two-way conversation could begin before the ground team reaches the person.

Why height changes the picture

The main advantage is not necessarily greater transmit power. It is position.

An elevated relay can gain radio visibility to areas separated by ground-level obstructions. A study by McRae and colleagues, published in 2021, tested this principle in ten locations in southern Utah during simulated rescue deployments. After confirmed loss of contact, a repeater-equipped drone was raised 122 metres above incident command. Contact was restored at all ten locations and maintained for the remainder of each exercise. Read the study.

This demonstrates feasibility under the study's conditions, not guaranteed performance everywhere. The study does not validate the proposed pod delivery or Skylens automation. Its flight height is a reported experimental condition, not operating guidance.

When one drone is not enough

In complex terrain, one relay may not have a viable link to both ends of the network. Multiple aircraft could be considered:

Ground team → drone 1 → drone 2 → drone 3 → remote team

Every hop must satisfy the radio system's requirements. Line of sight is only part of that assessment: link margin, Fresnel-zone clearance, interference and protocol compatibility also matter.

A properly engineered system could support a temporary multi-hop or mesh network. A chain of ordinary voice repeaters does not automatically become a mesh network; compatible networking and routing equipment are needed.

Rather than constructing towers, the concept is to create a temporary communication corridor over an area lacking infrastructure.

A dynamic system

A more advanced development goal is to calculate relay positions rather than select every hover point manually.

Given a terrain model, ground-unit locations and radio characteristics, the system could ask:

Where could a drone establish viable links to both ends?

For multiple aircraft:

How many relay nodes are needed, and where should they be positioned?

The proposed workflow is:

  1. Combine terrain data, ground-radio positions and radio characteristics.
  2. Analyze line of sight and candidate link geometry.
  3. Select a candidate relay position.
  4. Translate the candidate into a flight waypoint, subject to operational constraints.
  5. Measure the link and reassess the position.

This connects GIS, elevation models, mission planning and communications. A terrain-derived candidate still requires RF validation: the model may omit vegetation, recent structures or interference sources.

Why consider DJI Enterprise platforms?

The concept does not necessarily require a new aircraft.

DJI provides a Payload SDK for integrating custom payloads with compatible platforms. This offers a starting point for assessing a modular integration, not confirmation that the proposed relay works with every aircraft. No verified aircraft, radio or delivery mechanism is specified here.

The architecture could have two principal payload elements.

Air Relay Module

The unit that stays with the drone: radio, antennas, controller, power supply and telemetry.

Ground Communication Pod

A small, rugged unit delivered to the ground, allowing the recipient to talk to the rescue team.

The pod need not expose the controls of a professional radio. A simple push-to-talk interface may be more useful for someone unfamiliar with the equipment.

Beyond search and rescue

The same architecture could be explored for:

  • Natural disasters, earthquakes and damaged communication infrastructure.
  • Wildfires and floods, subject to the incident's operational constraints.
  • Remote infrastructure sites and mines.
  • Work in mountainous areas.
  • Teams separated by terrain.
  • Temporary connectivity before fixed infrastructure is deployed.

The aircraft would not simply reach a location quickly. It could bring a piece of infrastructure with it.

The real challenge is not just the drone

Carrying a radio is only part of an operational system. Development must also address:

  • Payload mass and energy consumption.
  • Flight endurance and weather limitations.
  • RF interference between the aircraft and communication payload.
  • Antenna design and installation.
  • Frequencies, licensing and applicable permissions.
  • A safe delivery mechanism.
  • Loss-of-link behaviour and other fail-safe conditions.
  • Relay altitude and position selection.
  • Continuity while aircraft or batteries are exchanged.
  • Coordination of multiple relay nodes.

In a multi-hop system, another question becomes central: who decides where every drone should be?

Terrain data and GIS would become part of communication planning itself—not a substitute for field measurements or operational judgment.

From drone mapping to drone infrastructure

We usually think of drones as sensors. They photograph, measure and scan, producing maps and three-dimensional models.

Another possibility is drone as infrastructure.

A drone can be a node in a radio network, a sensor network or a mesh network: a temporary element placed where infrastructure is missing and removed when the operation ends.

Combining a three-dimensional terrain model with dynamic node positioning could help create temporary networks adapted to the landscape.

The question we want to investigate

At Skylens, we are exploring this as an R&D concept:

Can an existing enterprise drone become a system that locates an isolated person, delivers a communication device and establishes an airborne radio bridge to a rescue team?

The next step is to assess hardware, RF, payload integration, line-of-sight planning and the operator interface. Automated deployment remains a development objective, not a demonstrated Skylens capability.

We would welcome practical experience from people working in search and rescue, RF engineering, emergency communications, mesh networks and DJI payload development.

Sometimes connecting two points on the ground starts with adding a third point in the sky.

Frequently asked questions

Is this a Skylens system available for rescue operations?

No. It is an R&D concept requiring hardware selection, RF testing, safety trials and performance validation. It should not currently be relied upon as an available emergency communication system.

Will a single drone always be enough?

No. Terrain, antennas, frequency, interference and endurance affect the link. Another approach or several compatible relays may be required.

Does the repeater replace cellular infrastructure?

Not necessarily. This article concerns a radio bridge between compatible devices, not a promise of cellular service or internet access.

Sources and further reading

This is a concept overview, not an operational rescue manual or a replacement for professional engineering.