Analysis of antenna impact on wide-band indoor radio channel and measurement results at 1 GHz, 5.5 GHz, 10 GHz and 18 GHz

The object of this paper is to investigate the influence of antenna pattern on indoor radio channel characteristics. Different from previous works where this analysis was carried out at a fixed frequency using different antennas, in the present paper (where measurements were taken in a wide frequency range) the variation of the radiation pattern was caused by two factors: the change of the radiation pattern when the same antenna was used at different frequencies and the use of different type of antennas. To carry out this analysis, frequency domain measurements of the indoor radio channel at 1 GHz, 5.5 GHz, 10 GHz and 18 GHz were collected. Measurements were taken using a network analyzer. Several realizations of the channel transfer function were obtained varying, for each measurement, the position of the transmitter and keeping the receiver fixed. Estimate of the channel impulse response was obtained from the Inverse Fourier Transform (IFT) of the frequency response. The measurements were performed in an office environment with mostly metallic walls and inner separations. The obtained data were elaborated to obtain the power versus distance relationship, the Cumulative Distribution Functions (CDFs) of rms Delay Spread (DS) and of the 3 dB frequency correlation bandwidth. Finally, the 3 dB width of the frequency correlation function has been empirically related to the inverse of the rms DS of the impulse response.