Design and Simulation of Log Periodic Dipole Array Antenna for 162 MHz AIS receiver

The AIS device installed at the Communication Systems Laboratory of Electrical Engineering Department, Faculty of Engineering, Udayana University does not have optimum performance indicated by the AIS report data cannot be received or is lost in continuous time intervals. One of the reasons is that the AIS communication system using omnidirectional antenna has narrow transmission capacity and works at VHF frequencies where the reliability of the communication system is influenced by the contours of the earth's surface. A log periodic dipole array (LPDA) antenna is designed to change the radiation pattern of the omnidirectional antenna to directional so that the AIS reception coverage area is able to reach the entire KKP Nusa Penida area and its surroundings. The log periodic dipole array antenna on the AIS device is planned to operate in a frequency of 162 MHz. The value, σ is chosen which is not larger than 0.150, and since the antenna was set up to posseses gain of 7 dB, the value, τ is 0.826. Based on the simulation with software 4NEC2, the 3-elements antenna that has been designed posseses gain of 6.35 dB which is greater than that of the omnidirectional antenna, VSWR of 1.49 and Front to Back Ratio (F/B) of 13.5 dB at a frequency of 162 MHz.