Radio frequency sensitivity test

Radio Frequency Sensitivity Testing Service – Accredited ISO/IEC 17025 Electromagnetic Compatibility and Receiver Performance Assessment for the Croatian Market

Radio frequency (RF) sensitivity is a fundamental performance parameter that quantifies the ability of a radio receiver, wireless device, or communication system to detect and process low‑level RF signals in the presence of noise and interference. Accurate measurement of RF sensitivity is essential for ensuring reliable communication, data integrity, and operational safety in a wide range of applications, including mobile phones, base stations, satellite communications, automotive radar, medical telemetry, industrial IoT devices, and defense systems. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Hrvatska regulatorna agencija za mrežne djelatnosti (HAKOM), the Državni inspektorat, and the Carinska uprava enforce strict EMC and radio equipment standards aligned with EU directives (including the Radio Equipment Directive 2014/53/EU and the EMC Directive 2014/30/EU) and HRN EN (Croatian standards based on European norms), the accurate evaluation of RF sensitivity is essential for product certification, CE marking, type testing, supplier qualification, and import‑export processes. Our laboratory offers a comprehensive radio frequency sensitivity testing service, applying standardized methods such as EN 300 220, EN 300 328, EN 301 489, ETSI TS 103 361, IEC 61000-4-3, and IEC 61000-4-6 to measure sensitivity, selectivity, blocking, and intermodulation performance under controlled RF and environmental conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, product validation, and market access in Croatia and the European Union.

Wireless Devices and Radio Equipment We Regularly Test

Our laboratory receives a wide variety of wireless devices and radio equipment for RF sensitivity testing. Typical samples include:

• Mobile phones and handheld devices – smartphones, tablets, and portable communication terminals.
• Short‑range devices (SRD) – remote controls, keyless entry systems, garage door openers, and wireless sensors.
• Wireless networking equipment – Wi‑Fi routers, Bluetooth devices, Zigbee modules, and LoRaWAN nodes.
• Automotive and telematics equipment – vehicle‑to‑everything (V2X) modules, tire pressure monitoring systems (TPMS), and GPS receivers.
• Medical telemetry and implantable devices – wireless patient monitors, infusion pumps, and pacemaker programmers.
• Industrial and IoT devices – wireless transmitters, data loggers, and smart meters.
• Defense and professional communication equipment – tactical radios and military communication systems.
• Prototype and new radio designs – submitted by manufacturers for validation of RF sensitivity before series production.
• Field‑retrieved equipment – for performance degradation analysis and troubleshooting.

Receiver Sensitivity Measurement – Minimum Detectable Signal Level

Receiver sensitivity is the minimum input signal level (in dBm) required for the receiver to achieve a specified bit error rate (BER) or frame error rate (FER). Our tests measure the sensitivity of radio receivers under controlled, interference‑free conditions, using calibrated RF signal generators and test software.

• Sensitivity test – bit error rate (BER) method (EN 300 220 / EN 300 328 / HRN EN 300 220 / NTC 5600 – for short‑range devices) – we connect the receiver to a calibrated RF signal generator via a shielded cable (or a radiated test setup). The generator is set to the carrier frequency and modulated with a standard test signal (e.g., a PN9 or PN15 pseudo‑random sequence). The receiver is placed in a shielded enclosure (or in a fully anechoic chamber) to eliminate external interference. The signal level is reduced stepwise (e.g., 1 dB steps) until the BER reaches a specified threshold (typically 0.1 % or 1 %). The sensitivity is recorded as the input power (in dBm) at which the threshold BER is met. We report the sensitivity (in dBm), the modulation type, the data rate, and the test conditions.
• Sensitivity test – frame error rate (FER) method (ETSI TS 103 361 / NTC 5601 – for packet‑based systems) – for systems that use packet‑based communication (e.g., Wi‑Fi, Bluetooth, LoRa), we use a signal generator and a test software to transmit a specified number of packets at a controlled signal level. The FER is calculated as the percentage of packets that are lost or corrupted. The sensitivity is defined as the signal level at which the FER reaches a specified threshold (e.g., 10 %). We report the sensitivity (in dBm) and the FER threshold.
• Sensitivity test – carrier‑to‑noise ratio (CNR) method (NTC 5602 – for the signal‑to‑noise assessment) – we measure the CNR required for the receiver to achieve the specified BER. The sensitivity is calculated from the CNR and the noise figure of the receiver. We report the CNR (in dB) and the calculated sensitivity.
• Sensitivity test at different temperatures (NTC 5603 – for the thermal effect on sensitivity) – we perform the sensitivity test at different temperatures (e.g., -10 °C, 23 °C, 55 °C) to evaluate the effect of temperature on the receiver performance. We report the sensitivity at each temperature.
• Sensitivity test at different supply voltages (NTC 5604 – for the voltage sensitivity) – we vary the supply voltage (e.g., from 90 % to 110 % of the nominal value) and measure the sensitivity. We report the sensitivity as a function of the supply voltage.

Adjacent Channel Selectivity and Blocking – Evaluating Rejection of Interfering Signals

Adjacent channel selectivity (ACS) and blocking are measures of the receiver's ability to reject unwanted signals on neighboring frequencies. Our tests evaluate the receiver performance in the presence of strong interfering signals, which is essential for compliance with EMC and radio spectrum regulations.

• Adjacent channel selectivity test (EN 300 220 / EN 300 328 / NTC 5610 – for the rejection of nearby channels) – we set the receiver to a specified frequency and measure the sensitivity (as described above). Then, we introduce a second, interfering signal on an adjacent frequency (e.g., ± 1 MHz, ± 2 MHz) at a specified power level (e.g., 0 dBm). The sensitivity is re‑measured in the presence of the interference. The ACS (in dB) is calculated as the difference between the sensitivity with and without the interfering signal. We report the ACS (in dB) and the test conditions.
• Blocking test (NTC 5611 – for the rejection of strong out‑of‑band signals) – we introduce a strong interfering signal at a frequency far from the receiver's operating frequency (e.g., 10 MHz, 20 MHz away) and at a high power level (e.g., 0 dBm, 10 dBm). The receiver sensitivity is re‑measured. The blocking performance is reported as the reduction in sensitivity (in dB) caused by the interfering signal. We report the blocking attenuation (in dB) and the test frequency offset.
• Intermodulation rejection test (NTC 5612 – for the non‑linear mixing) – we introduce two interfering signals at frequencies (f1 and f2) that are spaced so that their intermodulation products (e.g., 2×f1 – f2) fall on the receiver's operating frequency. The sensitivity is re‑measured. The intermodulation rejection (in dB) is reported. We report the intermodulation rejection and the test frequencies.
• Selectivity test at different temperatures (NTC 5613 – for the thermal effect on selectivity) – we perform the ACS and blocking tests at different temperatures (e.g., -10 °C, 23 °C, 55 °C) to evaluate the effect of temperature on the selectivity. We report the ACS and the blocking attenuation at each temperature.
• Selectivity test with modulated interfering signals (NTC 5614 – for the realistic interference) – we use a modulated interfering signal (e.g., a WCDMA signal or a Wi‑Fi signal) instead of a continuous‑wave (CW) signal to simulate the real‑world interference environment. We report the ACS and the blocking performance with the modulated interference.

Radiated Susceptibility and Immunity – Evaluating Performance under RF Fields

Radiated susceptibility testing evaluates the ability of the receiver to maintain its sensitivity when exposed to an external RF field. This test is essential for ensuring the reliable operation of wireless devices in the presence of other radio transmitters and industrial RF sources.

• Radiated immunity test (IEC 61000‑4‑3 / HRN EN 61000‑4‑3 / NTC 5620 – for the RF field immunity) – we place the equipment under test (EUT) in a fully anechoic chamber (FAC) or a semi‑anechoic chamber (SAC) and expose it to a uniform RF field (from 80 MHz to 6 GHz) at a specified field strength (e.g., 3 V/m, 10 V/m). The field is generated by a broadband antenna connected to a signal generator and a power amplifier. The receiver performance (the sensitivity, the BER, or the FER) is monitored during the exposure. The immunity is assessed by the degradation in the performance. We report the field strength, the frequency range, the modulation, and the performance degradation.
• Radiated susceptibility test – tuned‑frequency method (NTC 5621 – for the narrowband susceptibility) – we sweep the frequency of the RF field across the receiver's operating band (and adjacent bands) at a fixed field strength, and we monitor the receiver performance. The frequencies at which the performance degrades are recorded. We report the susceptible frequencies and the performance degradation.
• Radiated immunity test with communication traffic (NTC 5622 – for the in‑service performance) – we establish a communication link between the EUT and a base station (or a test set) and monitor the link quality (the BER, the FER, or the throughput) during the RF field exposure. The immunity is assessed by the degradation of the communication link. We report the field strength and the link quality degradation.
• Radiated immunity test at different temperatures (NTC 5623 – for the combined thermal and RF stress) – we perform the radiated immunity test at different temperatures (e.g., -10 °C, 23 °C, 55 °C) to evaluate the combined effect of thermal stress and RF fields. We report the performance degradation at each temperature.
• Radiated immunity test with modulated fields (NTC 5624 – for the realistic field simulation) – we use a modulated RF field (e.g., AM, FM, or pulse modulation) instead of a CW field to simulate the real‑world RF environment. We report the performance degradation with the modulated field.

Transmitter and Receiver Integration – Evaluating the Complete System Performance

In many applications, the RF sensitivity of the receiver is influenced by the performance of the transmitter and the system integration. Our tests evaluate the complete transceiver system, including the transmitter leakage, the antenna mismatch, and the interference from the internal circuits.

• Transmitter‑receiver isolation test (NTC 5630 – for the self‑interference assessment) – we measure the leakage of the transmitter signal into the receiver input during transmission. The leakage can desensitize the receiver (de‑sense) and reduce the sensitivity. We report the isolation (in dB) and the desensitization (in dB).
• Antenna mismatch and reflection test (NTC 5631 – for the VSWR measurement) – we measure the voltage standing wave ratio (VSWR) of the antenna system at the receiver frequency. A high VSWR reduces the power transfer to the receiver and can degrade the sensitivity. We report the VSWR and the return loss (in dB).
• System sensitivity test (NTC 5632 – for the complete receiver system) – we measure the sensitivity of the complete receiver system (including the antenna, the RF front‑end, and the baseband processor) in its final enclosure. The system sensitivity is reported (in dBm).
• Desensitization test (NTC 5633 – for the interference from the internal circuits) – we measure the receiver sensitivity with the transmitter and the other internal circuits (e.g., the display, the processor, and the power supply) turned on and off. The degradation in the sensitivity caused by the internal circuits is reported. We report the desensitization (in dB) and the cause of the interference.
• System sensitivity at different orientations (NTC 5634 – for the radiation pattern and the sensitivity) – we measure the system sensitivity at different orientations (e.g., 0°, 45°, 90°, 180°) to evaluate the effect of the antenna radiation pattern on the receiver performance. We report the sensitivity at each orientation and the polar plot.

Environmental and Aging Effects on RF Sensitivity – Evaluating Long‑Term Stability

The RF sensitivity of a receiver can change over time due to aging, thermal cycling, humidity, and mechanical stress. Our environmental and aging tests evaluate the long‑term stability of the sensitivity, ensuring the reliability of the product over its service life in the diverse Croatian climate (coastal, continental, and mountainous).

• Thermal aging effect on sensitivity (NTC 5640 – for the heat‑aged devices) – we age the device in an oven at a specified temperature (e.g., 70 °C) for a specified duration (e.g., 7, 14, or 28 days), and then we re‑measure the sensitivity. We report the change in the sensitivity (in dB) and the retention of the performance.
• Humidity and moisture effect (NTC 5641 – for the moisture‑exposed devices) – we expose the device to a high‑humidity environment (e.g., 40 °C, 95 % RH) for a specified duration (e.g., 7 days), and then we re‑measure the sensitivity. We report the change in the sensitivity and the effect of the moisture.
• Thermal cycling effect (NTC 5642 – for the thermal fatigue) – we subject the device to repeated thermal cycles (e.g., from -20 °C to +60 °C) for a specified number of cycles (e.g., 100 cycles), and then we re‑measure the sensitivity. We report the change in the sensitivity and the effect of the thermal cycling.
• Mechanical shock and vibration effect (NTC 5643 – for the mechanical stability) – we subject the device to a mechanical shock (e.g., 30 g, 11 ms) and a vibration profile (e.g., 10‑500 Hz, 2 g) and then we re‑measure the sensitivity. We report the change in the sensitivity and the mechanical integrity.
• ESD effect on sensitivity (NTC 5644 – for the electrostatic discharge susceptibility) – we apply an electrostatic discharge (ESD) pulse (e.g., 4 kV, 8 kV) to the device's antenna connector (or the enclosure) and then we re‑measure the sensitivity. We report the change in the sensitivity and the ESD susceptibility.

Complementary Tests – Noise Figure, Gain, and Frequency Response for Sensitivity Characterization

To fully understand the receiver sensitivity and to identify the sources of performance degradation, we perform complementary tests, including noise figure measurement, gain measurement, and frequency response measurement.

• Noise figure measurement (NTC 5650 – for the receiver noise performance) – we use a noise figure meter (or a spectrum analyzer with a noise source) to measure the noise figure (NF) of the receiver (or the receiver chain). The NF (in dB) is a direct indicator of the receiver sensitivity. We report the NF and the gain.
• Receiver gain measurement (NTC 5651 – for the signal amplification) – we measure the gain of the receiver (the ratio of the output power to the input power) using a signal generator and a spectrum analyzer. The gain is correlated with the sensitivity. We report the gain (in dB) and the gain flatness.
• Frequency response and bandwidth measurement (NTC 5652 – for the receiver selectivity) – we sweep the frequency of the input signal across the receiver's operating band and measure the output power. The frequency response curve (the gain vs. frequency) and the 3‑dB bandwidth are determined. We report the bandwidth and the frequency response curve.
• Image frequency rejection measurement (NTC 5653 – for the superheterodyne receivers) – we measure the receiver's rejection of the image frequency (the frequency that is separated from the local oscillator by the intermediate frequency). A low image rejection can degrade the sensitivity. We report the image rejection (in dB).
• Local oscillator leakage measurement (NTC 5654 – for the LO spurious emission) – we measure the leakage of the local oscillator (LO) signal from the receiver. The LO leakage can cause interference to other receivers and can also degrade the sensitivity. We report the LO leakage (in dBm).

Test Report and Recognition in the Croatian Telecommunications, Automotive, and Industrial Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (RF signal generators, spectrum analyzers, power meters, and anechoic chambers) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the device (manufacturer, model, serial number, operating frequency, and modulation type).
• Detailed description of the test methods applied (ETSI/EN/IEC/HRN EN/NTC standards, test conditions, and measurement parameters).
• Numerical results: sensitivity (dBm), adjacent channel selectivity (dB), blocking attenuation (dB), noise figure (dB), gain (dB), and desensitization (dB).
• Graphical data: sensitivity vs. temperature curves, selectivity curves, and BER vs. signal level curves.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (ETSI EN 300 220, ETSI EN 300 328, ETSI EN 301 489, IEC 61000-4-3, HRN EN 300 220, and the requirements of the HZN, HAKOM, and Državni inspektorat).
• Statement of compliance with the Radio Equipment Directive (RED) 2014/53/EU and the EMC Directive 2014/30/EU.
• Photographs of the test setup, the device under test, and the test environment.
• Recommendations for design improvement (e.g., improved filtering, better shielding, and antenna matching) to enhance the RF sensitivity.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Hrvatska regulatorna agencija za mrežne djelatnosti (HAKOM) for radio equipment certification, by the Državni inspektorat for market surveillance, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of wireless and telecommunication equipment. Additionally, we offer consulting services for the design of sensitive receivers, the selection of appropriate RF components, and the implementation of EMC and radio compliance programs, contributing to the reliability, performance, and regulatory compliance of wireless products in the diverse and growing Croatian market, from the telecommunications and automotive sectors to the industrial IoT and consumer electronics industries.