Summary
KC901 is a radio frequency multimeter based on a network analyzer. Over the past decade, KC901 has undergone multiple improvements, distinguishing it by adding an extension after the serial number, such as KC901S. The latest product is the fourth generation.
Starting from 2022, our bureau has summarized the experience of previous products, combined with the pain points commonly reported by users, carefully organized the design work, and plans to launch models such as KC901J, K, R, T, B, etc. The fourth generation 901 adopts a 2N architecture, which significantly improves its functionality and performance.
It is expected that the fourth generation products will be ready in about a year. Similar to other community products, the initial software of the product was relatively simple and had fewer features, which will gradually improve within the next year or two, and users can remotely upgrade.
KC901K covers the frequency range of 5kHz~4GHz and is used to replace KC901S+in parallel.
For the network analyzer of fundamental wave mixing, it can be used as a simple signal source, field strength meter, comparator, and spectrum analyzer. Although its performance is lower than that of corresponding specialized instruments, it can completely help solve practical problems.
KC901 is designed for the community and popularization. On the one hand, it approaches or reaches the technical level of mainstream commodity instruments in the same period and tries to expand practical functions. On the other hand, it relies on structural innovation to achieve lower prices, making it an easily accessible tool.
We hope that the fourth generation KC901 can continue to accompany everyone on their journey of progress.
Differences from the previous generation KC90
The third generation KC901 is a 1.5 port analyzer. One port has all reflection measurement functions, while the other port is only used for transmission measurement.
KC901K is an alternative model to KC901S+, with two identical ports that can measure four S parameters without turning the device direction. KC901K supports 12 parameter dual port calibration.
With the development of software, KC901K will also support functions such as signal sources and field strength meters. Due to the built-in bridge installed on both ports, the output amplitude of the signal source is lower than the previous generation KC901, typically around 0dBm.
Due to the installation of bridges on both ports, the dynamic range of S21 is slightly smaller in the low frequency range (below 1GHz) than that of KC901S+. However, in the high frequency range, due to fundamental improvements in shielding, the dynamic range is significantly larger than the previous generation product.
All receivers of KC901K have removed AGC measures, and the use of amplifiers is extremely conservative, with the entire dynamic range being carried by ADC. Therefore, its linearity and stability have been unprecedentedly improved, but its spectral sensitivity has decreased by about 10dB compared to the previous generation of products.
Principle
The following figure is the RF block diagram of the fourth generation KC901 (for illustration only). Taking the measurement of S11 and S21 of a two-port device as an example, the path of the excitation signal is shown in red. After being generated by a frequency source, it is modulated by a stepper attenuator and a bypass amplifier. The forward reference signal R1 and reverse signal A are extracted through forward and reverse couplers, and output to the DUT through port 1. The output is from another port of the DUT to port 2, and the transmission signal B is extracted through the reverse coupler of port 2. The R1, A, and B signals are transformed into the same intermediate frequency through three identical mixers, filtered and amplified, and ready to be sent to the intermediate frequency unit.
The following diagram is an intermediate frequency block diagram. The R1, A, and B intermediate frequency signals are mixed for a second time on the intermediate frequency unit to obtain the second intermediate frequency. After being processed by the second intermediate frequency filter and ADC driver amplifier, they are finally sent to ADC for sampling. The data obtained by ADC is sent to the digital signal processing unit (DSP) to calculate the amplitude difference and phase difference.
If S12 and S22 of the device need to be measured, the excitation signal is output from port 2 to measure the amplitude difference and phase difference of the R2, B, and A signals. The measurement process is automatically managed by a computer and can obtain four S parameters.
Common technical parameters
The technical parameters are separately stated in the data manual. For ease of reference, commonly used parameters are listed here for reference.
*Some technical parameters are related to software, such as noise level, dynamic range, scanning speed, etc. With the improvement of the software, there may be significant changes. Please refer to the latest version of the actual parameters.