A study on the linear frequency modulated continuous and pulse wave radar systems

Abstract

The spiral-dipole antenna for the generation of circular polarization has been shown to be suitable for diversity techniques such as space, pattern, and polarization diversities in MIMO systems, achieving high isolation between antennas. The proposed antenna employs independent circular polarization by combining a dipole antenna and a spiral antenna. The dipole antenna is employed to generate vertical polarization and the spiral antenna to generate horizontal polarization. A decoupling technique is realized by two orthogonal polarizations, RHCP and LHCP. A phase change of 0˙ or 180˙ in one of the antennas can provide an interchangeable beam pattern, which is adoptable in the pattern diversity technique. The advantage of using the spiral is that its virtual current distribution is uniform, and thus it can emulate small loop current and thereby generate a smooth radiation pattern. An envelope correlation is compared with the dipole array, and it is shown that the proposed antenna will be applicable to MIMO systems. The PN sequence radar and the network analyzer are the most commonly used channel sounding devices. The PN sequence radar is used with a time domain analysis, whereas the network analyzer is based on a frequency domain analysis. The drawback of the PN sequence radar is that the spectral response of the rectangular pulse covers the overall frequency range. However, the network analyzer uses only specific frequency bandwidth to measure the magnitude and the phase of a signal. If the operating frequency of the network analyzer is increased, the measurement accuracy is degraded, because the scattering parameters are critically dependent on the experimental setup conditions. Moreover, the network analyzer is rarely applied to measure Doppler frequency. Instead a linear frequency modulated continuous wave (FMCW) radar based on a frequency domain analysis can be used. The whole system can be realized by an individual module for easy implementation. The FMCW ...