Matching Circuit to Improve Transmission Characteristic of Antenna for Undersea Communication

A matching circuit is required to improve the transmission characteristics of an antenna for undersea radio communication. Even if the reflection coefficient, $S_{11}$ , the transmission characteristics will not necessarily improve in a system with high radio-wave attenuation in the sea. Therefore, the authors designed a matching circuit to maximize transmission efficiency in the frequency band used. However, it is necessary to acquire the transmission characteristics between the antennas through experiment or simulation for circuit design. In the proposed circuit, an N-section LC ladder circuit is used. When the proposed matching circuits are connected to the antenna, the transmission coefficient is improved up to 12 dB.