Millimeter wave communication systems in the 21.5 to 29.5 GHz band are being developed in the United States and Canada for use in a local multipoint distribution service (LMDS). This paper summarizes radiowave propagation impairments for the LMDS and reports measurement data for small cells. Results include area coverage estimates over a range of basic transmission losses for 0.5-, 1.0- and 2.0-km suburban cells with foliated trees. Multipath, signal attenuation, depolarization, and cell to cell coverage also are discussed. Data indicates a high probability of non-line-of-sight paths due to trees which can cause signal attenuation and signal variability when wind is present. Signal variability was studied using k factors and compared to the Rician cumulative distribution function. Depolarization caused by vegetation and other signal scatterers was found to be an order of magnitude greater than rain-induced depolarization. A simple tapped delay line model is presented to describe multipath for three channel states.