In modern wireless communications, radar systems, satellite payload testing, quantum research, and RF module development, the microwave signal source—commonly referred to as a signal generator—plays a central role in system verification and performance evaluation. It provides stable, spectrally pure, and precisely controllable RF and microwave signals that are essential for R&D validation, production testing, and system integration.
With a wide range of signal generators available on the market, selecting the right model can be challenging. Performance specifications often look similar on paper, yet their real-world impact varies significantly depending on application requirements. This guide focuses on the core technologies of microwave signal sources and explains how to choose the most suitable instrument based on practical engineering needs. Using four representative TFN models—TG96, TG115, TG20A, and TG40A—as examples, we outline a clear and realistic selection strategy for engineers and test professionals.
Core Technical Factors That Define a Microwave Signal Source
Before comparing specific models, it is essential to understand the technical parameters that truly determine whether a signal source fits a given test scenario.
Frequency Range: The Foundation of Any Selection
Frequency coverage is the first and most fundamental consideration. A signal generator must fully cover the operating band of the device under test, with sufficient margin for characterization and future expansion.
For general RF testing, including IoT devices, broadcast systems, and most sub-6 GHz communication equipment, a frequency range from kilohertz up to 6 GHz is typically sufficient. Instruments such as the TFN TG96 are designed for this category and meet the needs of most routine RF applications.
Microwave and millimeter-wave testing, however, places far greater demands on frequency range. Applications such as satellite communication, radar systems, and 5G millimeter-wave front ends often require coverage up to 15 GHz, 21 GHz, or even beyond 40 GHz. Models like the TG115, TG20A, and TG40A address these higher-frequency requirements, enabling testing across Ku-, Ka-, and extended microwave bands.
Output Power and Dynamic Range
Output power capability directly affects how realistically a signal source can simulate operating conditions. A wide dynamic range allows engineers to test both weak-signal sensitivity and high-level signal tolerance using a single instrument.
High-performance microwave signal sources typically offer output levels from approximately –120 dBm up to +17 dBm, with fine amplitude resolution and stable accuracy. This is especially important in receiver sensitivity testing, gain compression analysis, and calibration workflows. The TG20A and TG40A stand out in this area, providing strong output power combined with precise level control.
Signal Purity: Phase Noise and Spurious Performance
Signal purity is one of the most critical—and often underestimated—factors in signal generator selection. Phase noise, harmonic distortion, and spurious emissions all have a direct impact on measurement accuracy.
Low phase noise is particularly important for high-order modulation schemes, narrowband receivers, and radar systems. Excessive close-in phase noise can degrade bit error rate (BER), reduce adjacent channel performance, and limit radar resolution. For example, the TFN TG115 achieves phase noise performance better than –115 dBc/Hz at a 10 kHz offset at 10 GHz, making it well suited for high-sensitivity receiver testing and low-noise local oscillator substitution.
Equally important are harmonic and spurious suppression levels. Strong suppression of unwanted signals minimizes interference during testing and improves confidence in measured results, especially when characterizing nonlinear devices or high-gain RF chains.
Modulation Capability and Signal Flexibility
Modern RF and microwave testing rarely relies on unmodulated carriers alone. A practical signal source must support a wide range of modulation formats to simulate real-world operating conditions.
Analog modulation schemes such as AM, FM, and phase modulation remain fundamental, while pulse modulation is indispensable for radar and time-domain testing. Key parameters include pulse width range, rise and fall time, and on/off ratio. For communication and digital module testing, support for common digital modulation formats such as ASK, FSK, and PSK further extends application flexibility.
In this regard, instruments like the TG96 offer strong versatility, combining multiple modulation modes with external signal up-conversion capability for complex test setups.
Sweep Performance and Measurement Efficiency
Frequency and amplitude sweep functions are widely used for evaluating frequency response, bandwidth, and system-level behavior. Both sweep speed and dwell time control play an important role.
Fast frequency switching enables efficient production testing and automated measurements, while longer dwell times are better suited for steady-state analysis and precise characterization. High-end models such as the TG40A and TG20A are optimized for rapid sweeping, making them ideal for manufacturing environments where throughput is critical.
Application-Oriented Comparison of TFN Signal Generators
Understanding specifications is only part of the selection process. Matching those specifications to real application needs is what ultimately determines the right choice.
The TFN TG96 is designed as a highly versatile RF signal generator covering frequencies from 9 kHz to 6 GHz. Its comprehensive modulation support, external up-conversion capability, and attractive cost-performance ratio make it an excellent choice for education, general R&D laboratories, RF module testing, and service or calibration applications.
Stepping into the microwave domain, the TFN TG115 extends frequency coverage up to 15 GHz and focuses on signal purity. Its low phase noise and strong pulse modulation performance make it well suited for high-frequency communication research, radar signal simulation, and microwave component testing where spectral cleanliness is critical.
For users who require higher frequency coverage and stronger output performance but remain cost-conscious, the TFN TG20A provides an effective balance. Covering frequencies up to 21 GHz, it delivers wide dynamic range, high output power, and excellent phase noise performance, making it ideal for corporate R&D centers, communication equipment manufacturers, and production test systems.
At the top end of the range, the TFN TG40A offers frequency coverage from 9 kHz to 42 GHz, reaching into the Ka-band. With high output power, excellent spurious suppression, and fast sweep capabilities, it is designed for demanding applications such as satellite communication testing, millimeter-wave research, defense electronics, and advanced radar system development.
Practical Selection Strategy
In practice, selecting a microwave signal source comes down to aligning performance priorities with actual test requirements.
If your applications are limited to sub-6 GHz and require broad modulation flexibility, the TG96 provides ample capability without unnecessary complexity. For microwave applications up to 15 GHz where phase noise performance is a key concern, the TG115 is a strong and focused choice. When higher frequency coverage and stronger output power are required within a controlled budget, the TG20A offers an excellent compromise. For advanced research, satellite systems, and wideband microwave testing up to 42 GHz, the TG40A remains the most comprehensive solution.
Conclusion
Choosing the right microwave signal source requires a balanced evaluation of frequency range, signal purity, output power, modulation capability, sweep performance, and budget. Rather than focusing on specifications in isolation, engineers should consider how each parameter affects real-world measurement accuracy and test efficiency.
TFN’s signal generator portfolio covers the full spectrum of RF and microwave testing needs. From the multifunctional and cost-effective TG96, through the low-noise TG115, to the high-performance TG20A and wideband TG40A, each model is optimized for a clearly defined set of applications.
Before making a final decision, it is recommended to verify key specifications at the exact frequency points and modulation conditions relevant to your project. In many cases, pairing the signal source with appropriate options—such as high-stability reference oscillators or external up-conversion modules—can further enhance performance and future-proof your test platform.
👉 Compare detailed specifications of the TG96, TG115, TG20A, and TG40A to identify the microwave signal source that best matches your application requirements.