Radio Frequency (RF) testing has an important role in ensuring the products meet specific allowable standards for communication systems. This testing process uses Device Under Test (DUT) that refers to any piece of electronic equipment, device, or product that is being evaluated for its RF performance in these testing processes. The RF testing process involves several stages, starting from the DUT preparation, testing process for the specific items, until final reporting. This essay explores the RF testing process for a DUT, explaining its key components, methods, and importance in the industry.
1. DUT preparation for test
There are several types of Devices Under Test that can be used for RF test. Some RF test may require specific DUT types for its requirement. Here are some DUT types you need to know:
- Conducted DUT Type.
This DUT type is for the RF testing that needs direct reception from DUT to the test equipment (i.e spectrum analyzer, signal analyzer, cellular simulator, etc).
This DUT type also requires a modification on the DUT’s antenna port to have some specific antenna connector which usually uses SMA connector. This connector can be soldered directly to PCB board or it can use antenna cable that has the SMA connector.
This type of DUT also usually has been programmed to operate with some specific testing software or test tool. It can be programmed to continuously transmit the individual channel frequency or hopping frequency. - Radiated DUT Type
This DUT type is for the RF testing that does not need a direct reception from DUT to the test equipment, it is usually similar with the end products which we see in the market. There is no specific modification needed for this DUT.
2. Components of the RF Testing Process
The process of RF testing generally includes several essential components, such as the equipment used, the environment in which the tests are conducted, and the specific methods applied to evaluate the DUT’s performance.
- Test Equipment
A variety of specialized instruments and tools are used for RF testing. These tools include network analyzers, spectrum analyzers, signal analyzers, signal generators and power meters. Signal analyzers, for example, measure the DUT’s transmit power, occupied bandwidth, spurious emission, and etc. - Anechoic Chamber
RF testing typically takes place in an anechoic chamber, which is a designed room or chamber to reduce any interference and reflections. This chamber is also equipped with materials that absorb RF signals to prevent them from bouncing back onto the DUT, thus providing a more accurate measurement of its emissions and reception. - Test Setup
Before testing begins, the DUT must be properly configured with all necessary peripherals, such as antennas, cables, and power supplies. The setup may not be the same as the actual product operation. The test setup also includes connecting the DUT to measurement equipment in such a way that the signals can be monitored and measured. Test parameters like frequency range, signal modulation, and power levels must be defined before starting the test.
3. RF test items
There are various items of RF tests that a DUT may undergo, each focusing on different aspects of the device’s performance:
- Output Power and Sensitivity Testing
This test measures the output power of the DUT to ensure it meets the specified requirements. It also evaluates the DUT’s sensitivity to incoming signals, determining the minimum signal strength at which the device can effectively receive data. - Occupied Bandwidth
This test measures the bandwidth that occupies a certain power specified as a percentage of the total power in the acquired channel’s transmission waveform. The occupied bandwidth is more specific than a channel bandwidth as it only focuses in the centre or core portion where the peak power is concentrated within the channel transmission. - Spurious Emissions
It is ensuring that the DUT does not produce spurious signals or harmonics that could interfere with other electronic devices operating on nearby frequencies. RF testing involves measuring the levels of these unwanted emissions and ensuring they are within acceptable limits.
4. Importance of RF Testing and Conclusion
In the modern age of wireless technology, many products operate different frequency ranges from WLAN, BLUETOOTH, Cellular, and etc. this may cause huge interference to the similar or nearby frequency operation of the other products. This is why RF testing is very important to be done to make sure the radio frequency performance will not cause any interference or to ensure the radio frequency operates within the allowable ranges.
Additionally, RF testing is key to achieving compliance with international regulations. The Federal Communications Commission (FCC) in the United States, the European Telecommunications Standards Institute (ETSI) in Europe, and other regulatory bodies worldwide for example Indonesian Regulatory DJID https://www.dimulti.id/services/ establish limits on the amount of spurious emissions and interference that devices can emit. Products that do not meet these standards cannot be marketed or sold, making RF testing an essential step in the product development process.