Impact of Transmitter Antenna Height on the Rate of X-Band Communication System in Evaporation Duct Environment at 150 km

This paper investigates the impact of transmitter antenna height on the rate of X-band communication system at 150 km under various frequencies and evaporation duct heights (EDHs), using both simulated path losses (PLs) and observed rate. The results show that when the EDH is relatively lower, increasing the height of transmitter antenna extends the propagation distance of electromagnetic (EM) wave within the line-of-sight (LOS) range, thus improving the communication rate; in contrast, when the EDH is higher, a lower antenna height can achieve higher rate. In December 2024, cross-sea experiments were conducted by the developed X-band communication system on an over-the-horizon (OTH) communication link with 150 km in the northern South China Sea (SCS). Experimental results demonstrate that when the EDH is relatively high (e.g., 14.3 m), the average rate achieved by the transmitter antenna with a height of 8.62 m is 0.25 Mbps higher than that achieved by the height of 12 m.