Multiple factors such as the environment, hardware performance and energy management of the spacecraft determine that it can just use the control input with low-frequency. Based on this, this paper investigates the relative attitude controller for the tethered main and sub-satellite payloads equipped with terahertz communication devices during the ejection deployment process, as well as the implementation of continuous and opportunistic communication via terahertz on mobile platforms. The controller enables the relative attitude between main and sub-satellites to achieve terahertz communication at lower control frequencies. The ground experiment integrating tethered satellites ejection deployment and terahertz communication was conducted with the controller. The experimental results show that under low-frequency control, the designed controller not only allows the sub-satellite simulator's trajectory to closely follow the pre-designed optimal deployment curve, but also meets the relative attitude angle requirements for continuous and opportunistic communication via terahertz between the main and sub-satellites. The terahertz communication rate and bit error rate demonstrate that the adaptability of terahertz communication on mobile platforms for both opportunistic and continuous communication meets the required standards.