Tutorial on MIMO (multiple input/multiple output) techniques and how they differ from other multiple access strategies. Charan Langton's tutorials are excellent resources for learning complex communications concepts. The bibliography at the end provides a good starting point for further research as well.
This app note gives some good background for improving the accuracy of noise figure measurements.
Some noteworthy topics covered include: when to use a noise source with a larger or smaller ENR, choosing the appropriate measurement bandwidth, and factors to take into account when making measurements on frequency-conversion devices (mixers).
These lecture notes provide comprehensive coverage of mixer types as used in RF and microwave applications. Three approaches to producing the multiplication of two signals are described: using nonlinear behavior of a diode or transistor, switching, and sampling. Major mixer topologies are also introduced. These notes may be more detailed than what many people are looking for, but they are still worth reading over to gain an understanding of the different mixer strategies.
This app note gives a good understanding of the operation of switching type mixers. "Switching type" refers to the implementation of the mixing operation by using the diode or transistor as a switch that turns the RF signal on and off or inverts its polarity at the LO frequency. Another type of mixer implementation is to bias the diode so that it operates in the square law region so that the output includes the square of the input.
This app note briefly discusses ten different useful topics related to making VNA measurements.
From the table of contents:
HINT 1. Measuring high-power amplifiers
HINT 2. Compensating for time delay in cable measurements
HINT 3. Improving reflection measurements
HINT 4. Using frequency-offset for mixer, converter and tuner measurements
HINT 5. Increasing the accuracy of noninsertible device measurements
HINT 6. Aliasing in phase or delay format
HINT 7. Quick VNA calibration verification
This app note describes the techniques that can be used to measure devices requiring a high input signal level. Although the steps listed are specific to the E5072 ENA Network Analyzer, the concepts of using a configurable test set apply to other brands and models as well.
These slides from a webinar presentation give a detailed overview of the principles of measuring phase noise. The underlying relationships between phase noise spectral energy, demodulated phase noise, frequency etc. are described. The presentation also includes a description of the "modern" definition of phase noise along with current measurement techniques.
These seminar notes give a good discussion of the principles of phase noise. Specifically the authors describe the difference between measuring phase noise directly or using phase/frequency demodulation techniques. The notes describe details about the limitations and equipment performance requirements for making phase noise measurements using a variety of techniques. Since these notes are from an older archive, the latest techniques involving the use of correlation are not described.
Logarithmic amplifiers provide an output voltage that is logarithmically scaled relative to the amplitude envelope of the input signal. Historically these have been used to provide logarithmic Y-axis scaling to spectrum analyzer displays, for example. This app note describes the basic block diagram and principles of operation of a log amplifier.