  THz band is envisioned to be used in 6G systems to meet the ever-increasing
demand for data rate. However, before an eventual system design and deployment
can proceed, detailed channel sounding measurements are required to understand
key channel characteristics. In this paper, we present a first extensive set of
channel measurements for urban outdoor environments that are ultra-wideband (1
GHz 3dB bandwidth), and double-directional where both the transmitter and
receiver are at the same height. In all, we present measurements at 38 Tx/Rx
location pairs, consisting of a total of nearly 50,000 impulse responses, at
both line-of-sight (LoS) and non-line-of-sight (NLoS) cases in the 1-100 m
range. We provide modeling for path loss, shadowing, delay spread, angular
spread and multipath component (MPC) power distribution. We find, among other
things, that outdoor communication over tens of meters is feasible in this
frequency range even in NLoS scenarios, that omni-directional delay spreads of
up to 100 ns, and directional delay spreads of up to 10 ns are observed, while
angular spreads are also quite significant, and a surprisingly large number of
MPCs are observed for 1 GHz bandwidth and 13 degree beamwidth. These results
constitute an important first step towards better understanding the wireless
channel in the THz band.
