Torsti Poutanen

Implementation techniques of broadband radio channel simulators

This paper discusses the advantages and disadvantages of different implementation techniques of radio channel simulators and analyses in more depth the challenges of increasing bandwidth and dynamic range. One selected technology has been implemented and tested. A block diagram of the simulator and test results are shown.

Correlation control in the multichannel fading simulators

Future broadband communications systems will utilize antenna array based smart-antenna systems. Novel receiver architectures will provide interference cancellation techniques based on antenna beam steering. These developments will pose new requirements to the existing multipath fading simulators. This paper describes two methods to generate fading channels with controlled mutual correlations. The third topic covers an important hardware calibration issue relevant in reproducing accurate correlations between the channels.

Uncertainty of Radiometer Calibration Loads and Its Impact on Radiometric Measurements

We present an uncertainty analysis of radiometer calibration. The procedure can be used to determine the uncertainty in the nominal brightness temperature of the unknown scene. A total power radiometer requires frequent calibration with known reference loads that are connected to the radiometer. Our analysis includes uncertainties from the radiometer calibration loads and from the connecting network (CN) that is required to multiplex calibration loads and scene to the radiometer input. We show the design and analysis of three calibration loads and how their uncertainties propagate from load terminals to the radiometer calibration plane and to the scene. All three loads, including a cryogenic load, are simple, inexpensive, and show great stability and accuracy. We give an uncertainty calculation example for our three calibration loads and for the CN. We validate our model and the long-term stability of the loads through measurements. The analysis is done at 52 GHz, but the analysis and the construction of the loads are generic and easily scalable to other frequencies.