28GHz rural close-to-ground propagation field test results and models

A set of 28 GHz close-to-ground propagation measurements are conducted for different rural outdoor scenarios at the National Spectrum Centre, Aberystwyth. A bespoke correlation based channel sounder and horn antennas are employed in the measurement system. The measurements provide large-scale path loss, time domain impulses and channel measurements that will be beneficial for rural future millimeter wave communication systems. Different scenarios, such as straight and elevated paths, zig-zag curved road and curved road in woods are explored and log-normal models are extracted. Propagation measurements in diverse terrains including hill, grass land, dense forest and buildings are also conducted. The path loss predictions of existing foliage loss models like Weissberger, ITU-R, COST and FITU-R are investigated with frequency and distance. Then, the measured path losses are compared with these models. Predicted pathloss values of these models are overestimated at 28 GHz in dense tree forest after 50 m. Strong reflections are observed in the propagation through buildings at log(d) distance of 1.6 and 1.9. Similar path loss attenuations and fixed offset values (nearly 22 dB more than free space) are observed in the propagation through the dense forest and curved road in woods. The presented close-to-ground propagation research is significant for future military applications and mobile device-to-device communications.