INFLUENCE OF MICROSTRIP PATCH ANTENNA HEIGHTS ON WIDE-BAND CHANNEL PARAMETERS IN A STATIC INDOOR CHANNEL

The paper presents the wideband parameters of an indoor channel such a s the path loss characteristics and root mean square (r.m.s.) delay sp read in a typical laboratory setting. Different antenna height configu rations were used in the experiment. Measurements were made by using a vector network analyser at 1.95 GHz using directive patch antennae. T he path loss characteristic changes with the different types of antenn a height configuration. For line-of-sight (LOS) the n value ranges fro m 2 to 2.9, whereas for an obstructed path (OBS) it ranges from 3.3 to 3.6. Similarly, the median r.m.s, delay spread ranges from 6.2 ns to 10.4 ns in LOS. However, the r.m.s. spread delays obtained are constan t and are based on the type of antenna height configuration for OBS. F or the same antenna height configuration, it centres on 25 ns, whereas the optimized configuration is at 19 ns. The correlation of r.m.s. de lay spread with transmit-receive (T-R) distance is high in LOS, but no t when different antenna height configurations are considered. However , in OBS it is explicitly dear that r.m.s. delay spread is independent of distance. Generally, the r.m.s. delay spread increases when the pa th loss characteristics are more severe. The results presented here ad vocate the choice of directional antennae for a typical indoor wireles s LAN environment, as compared with that of an omni-directional antenn a. Moreover, careful selection of antenna height at the base station t o avoid the Fresnel zone is essential for optimal performance. This se lection yeilds an n exponent value following very closely free space p ropagation, and it has the lowest r.m.s. delay spread with median valu e of 6.2 ns.