Monopole Antenna for Communication System of Military Vehicle at HF Band 3–30 MHz

Antenna plays an important role in military purposes. A good antenna can receive and transmit long-distance frequency signals and with little interference that enables long-distance radio communication with clear and good sound. Existing military vehicle antennas in the industry are mostly installed at the roof of the vehicle. However, the difference in the location of the antenna on the roof, will affect the radiation pattern and the operating frequency of the antenna. Negative effects are able to degrade the performance of the antenna hence affecting the communication in a group. Therefore, this study focuses on the objective of designing and simulating a monopole antenna for military vehicles with optimum bandwidth operating at 15 MHz. Frequency responses and radiation patterns of monopole antennas mounted in four different locations on the roof of a test military vehicle were measured. Additional measurements were performed when the vehicle was simulated with different types of ground plane. These are to show the effects of different antenna location on the vehicle and also the effects of different types of ground plane. Antenna at the center of the roof of the vehicle has the most optimal S-parameter results with desired operating center frequency at 15 MHz. Antennas at other locations on the vehicle and also when the vehicle are simulated with different types of ground plane, shows degradation in frequency response and radiation pattern. The effects of center frequency shifting and distortion of radiation pattern were able to degrade the performance of the antenna. These were improved by using a matching circuit for frequency tuning. A matching circuit is designed and can be used to tune in the desired operating frequency by changing the value of capacitance in order to overcome the effect of frequency shifting.