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This paper discusses a method in which a wave source is visualized by electromagnetic wave holography by scanning the receiver antenna on a plane. The method presented in this paper does not use the Fresnel approximation or the Fraunhofer approximation, and there is no constraint on the distance between the measuring plane and the object of observation. By partitioning the object of observation, the method can be applied, even if the object of observation is larger than the hologram measuring plane. The two‐dimensional fast Fourier transform is introduced to each of the partitioned planes, so that the speed of the numerical integration is improved. To improve the accuracy of the intensity of the reconstructed image, the directivity of the receiving antenna is considered. For observation of the leaked electromagnetic wave in a real system, a hologram observation system is proposed in which some variation of the observation frequency can be tolerated. Using the proposed observation system, the radiation from a dipole antenna is observed, and a computer simulation is performed. These results show that the resolution is improved and that a wider range of observation is realized than in the conventional method. Lastly, as an application example, the leaked electromagnetic waves from a metal cabinet are observed on a 57 cm × 57 cm plane at a distance of 200 cm, and a visualized result for 285 cm × 285 cm is presented. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 82(8): 52–60, 1999

Development of high-speed wireless LANs is a major goal of telecommunications industry. We propose a dual-frequency continuous wave (CW) radio holography method for evaluating radio wave propagation environments for such LANs. Our method images the propagation environment with higher resolution (1 ns or less) and higher sensitivity (10 dBDVV/m) than convenconventional techniques which use frequencymodulated CWs (FMCWs), pseudonise (PN) codemodulated waves, or pulse-modulated waves. A narrowband technique virtually eliminates the measurement inaccuracy caused by frequency response dispersion which is often a problem in conventional methods. This paper introduces the new radio wave propagation observation method by presenting examples of indoor propagation images and delay profiles observed at around 18 CHz.

In cellular communications systems using digital radio services, especially those that use lowearth orbiting satellites ( L E O S ) , phase-modulated signals such as QPSK are received with relatively fast Doppler shifts. We developed a coherent detector which uses a new algorithm called the spectrum phase interpolation method (SPIM) to compensate for the Doppler shifts. SPIM will aid TDMA propagation analyses of QAM and QPSK modulated waves and orthogonally vector spread spectrum modulated waves.precisely or tracking from instantaneous spec received signals subjec shifts. Our algorithm, called interpolation methodSystems : modulated vectors ral information on ed to fast Doppler he spectrum phase (SPIM), uses a frequency linear phase interpolation approximation expression t o measure the absolute values of frequencies, amplitudes and phases in each instantaneous fast Fourier transform (FFT) spectrum observed, through hanning windows [ 4 I .

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