A practiacal guide for Engineers and Product Managers - answered by a Field Application Engineer (FAE)
Target audience: Developers, Product Managers & System Architects
Reading time: approx. 7 minutes
Focus: Radar Sensor Integration, Requirements Analysis
Choosing the right radar sensor can determine the success of a high-tech project. This guide answers the 7 most critical technical questions you should address before selecting a sensor – from target objects (RCS) and detection range to housing materials (radomes), data interfaces and certification for series production.
Avoid costly redesigns by defining clear specifications at the start of your project.
Introduction: Why sensor selection is critical at the start of a project
The choice of sensing technology has a major impact on the entire product development process. Radar sensors offer clear advantages over optical or ultrasonic solutions. They operate reliably in darkness, fog, dust and rain. They can also measure motion, speed, distance and angle through plastic housings.
Nevertheless, some sensor projects fail because the specifications were not clearly defined at the beginning of the planning process.
A radar sensor is not simply a standard component. It must be precisely matched to your application. Misjudging the requirements can result in high costs and delays. A Field Application Engineer (FAE) advises customers on these technical decisions every day. In this article, an FAE answers the seven most important questions to help you lay the foundation for a successful radar project.
Question 1: What exactly should the sensor detect or measure?
The first question defines the basic function of the radar sensor. In practice, engineers distinguish between several different measurement tasks. You need to determine which parameters your application requires:
- Presence and motion detection: Simply detecting whether an object is present within the detection area (Doppler radar).
- Distance measurement: Precise determination of the distance to a target (FMCW radar).
- Speed measurement: Accurate measurement of the speed of moving objects.
- Direction of movement: Distinguishing between approaching and receding objects.
- Angle measurement and 3D positioning: Measuring azimuth and elevation to determine complete target coordinates.
A common misunderstanding relates to expectations. Radar is not an optical camera system. It detects radio-frequency reflections rather than visual details. If you expect edge or shape recognition comparable to an image-processing system, radar is the wrong approach. Radar is ideal when robust detection under difficult environmental conditions is required.
Question 2: Which objects and environmental conditions do you need to cover?
Not every object reflects radar signals equally well. The key term here is Radar Cross Section (RCS). A metal truck has a very large RCS, while a pedestrian or a wooden object has a significantly smaller RCS.
The FAE explains:
“Radar detects metal much better than water or tissue. Objects with edges and corners are detected very well, whereas a metal cup is round and, like all rounded objects, reflects less strongly. You therefore need to define exactly which targets must be detected.”
You should also consider interfering objects in the surrounding environment. Trees moving in the wind, passing cars or heavy rain can generate signals. The radar system must be able to distinguish genuine targets from unwanted reflections. This is achieved through targeted filtering in the algorithms.
Question 3: What detection range and Field of View (FOV) do you really need?
Engineers frequently make incorrect assumptions when defining the detection area. Range and opening angle – or Field of View (FOV) – are directly related by the laws of physics. The performance of a radar sensor cannot simply be extended indefinitely.
| Parameter | Wide Field of View (e.g. 100° × 40°) | Narrow Field of View (e.g. 12° × 12°) |
|---|---|---|
| Antenna gain | Lower focus, wide coverage | Strong focusing of the signal |
| Range | Shorter (e.g. 5 to 15 metres) | Very long (e.g. 50 to 150 metres) |
| Main application | Room monitoring, automatic door openers, blind-spot monitoring | Perimeter protection, traffic measurement |
A radar sensor cannot simultaneously measure over a distance of 100 metres and cover a wide field of 120 degrees without a significant increase in transmit power.
You should therefore define realistic requirements. Avoid adding unnecessary safety margins. An excessively large detection area increases costs and also raises the risk of false triggers caused by unwanted objects at the edges of the detection zone.
Question 4: What are the installation conditions and housing (radome) like?
One of radar’s major advantages is that it can be integrated invisibly. The sensor can be installed completely behind a plastic cover. This cover is known as a radome.
However, unsuitable housing materials can significantly attenuate or reflect the radio waves.
Follow these guidelines for an optimal radome:
- Suitable materials: ABS, polycarbonate (PC), acrylic or special plastics without metallic additives.
- Unsuitable materials: Metals, carbon-fibre-reinforced plastics, damp wood or glazed ceramics.
- Wall thickness: The thickness of the plastic must be precisely matched to the radar wavelength, for example a multiple of lambda/2. Incorrect wall thicknesses can cause internal reflections.
- Distance from the sensor: The radome must maintain a defined distance from the antenna. Make sure that no water can accumulate in this space.
Mechanical environmental influences must also be considered. Strongly vibrating housings can distort speed measurements. The sensor should therefore always be mounted on a stable surface.
Question 5: What output data does your system architecture require?
Radar sensors provide different levels of data. The type of processing determines how much computing power is required on your side. You therefore need to decide where the signal processing should take place.
FAE insider tip:
“Decide at an early stage whether your own main processor should perform the mathematical algorithms or whether you expect the sensor to provide processed object data. This can save months of development time.”
The following interfaces and data formats are available:
- Digital I/O (switching signal):
The sensor outputs a simple high/low signal (“object detected” or “no object”). This requires no processing power on the customer side. - Processed object data:
The sensor provides processed values such as distance, angle and speed via UART, CAN or SPI. The customer processes the resulting data packets directly. - Raw data (IQ / FFT):
The sensor provides raw analog or digital signal values. The complete signal processing and object detection are carried out on the customer’s controller. This offers maximum flexibility but requires in-depth radar expertise.
Question 6: Is a standard sensor sufficient or does the project require customization?
Standard radar sensors – COTS (Commercial Off-The-Shelf) products – cover many applications. They are readily available and reduce development costs.
However, standard modules can reach their limits when specific requirements need to be met.
A customized module can make sense in the following situations:
- Special space constraints: The available installation space requires a customized PCB shape.
- Custom antenna designs: The coverage area must be precisely adapted to a challenging geometry.
- Specific software algorithms: Signal processing must filter out particular sources of interference or detect specific motion patterns.
- Cost optimization for high volumes: Components that are not required can be removed for series production.
Experienced suppliers such as RFbeam Microwave offer flexible customization options – from firmware modifications to completely new hardware and antenna designs.
Question 7: What is the path from prototype to series production?
The transition from an initial idea to series production follows several clearly defined phases. The FAE recommends a systematic approach:
Phase 1: Evaluation Using Evaluation Kits
Do not start immediately with hardware development. Use the manufacturer’s Evaluation Kits (EVKs) first.
These test boards allow you to verify feasibility both on the bench and in the field within just a few days.
Phase 2: Prototyping and Field Testing
Integrate the sensor into your test housing. Check the performance of the radome and test the software under real-world conditions.
Phase 3: Certification for Series Production (CE / FCC)
Every radar product emits radio-frequency radiation and therefore requires radio certification.
Make sure that the sensor manufacturer already offers pre-certified modules. This can significantly simplify certification of your complete system and save substantial laboratory costs.
Conclusion: Good preparation saves development time
A radar project requires a precise requirements analysis from the outset. By answering these 7 questions before development begins, you can avoid costly mistakes.
You can select the right sensor type, design the housing correctly and optimize the data-processing architecture for your application.
Radar technology offers unique advantages for modern B2B applications. With an experienced development partner at your side, the transition from concept to series production can be achieved safely and efficiently.
Planning a specific radar sensor project?
Our Field Application Engineers support you from the initial specification through to series production. Feel free to contact us for individual advice.