The Need

VHF antennas operating over the frequency range of 30-3000 MHz are widely used for short-distance terrestrial communications. Monopole antennas are the most commonly used for VHF communications. However, monopoles require a quarter wavelength height and have narrow bandwidth. Some attempts have been made to improve upon the narrow bandwidth of monopole antennas, however the designs of these improvements still require significant antenna heights. Some have improved upon the height of monopole antennas, but these antennas do not have wide bandwidth. Currently, there is a need for VHF antennas that are both low profile, and have wide bandwidth.

The Technology

Researchers at The Ohio State University, led by Dr. Chi-Chih Chen, have developed a novel 30-300 MHz low profile antenna. The antenna has a diameter of 60.96 cm and height of 5.08 cm, which is significantly smaller than typical VHF antennas. The key development in the technology is the use of ferrite loading, which led to large gain improvement at 30 MHz, and more stable gain above 100 MHz, allowing for a wider bandwidth.

Commercial Applications

• TV broadcast
• Amateur radio
• Land mobile communications
• Marine communications
• Air navigation systems

Benefits/Advantages

• Very low profile, with height more than 7x lower than most legacy VHF antennas
• Wideband operation
• Very large gain at 30 MHz, and more stable gain above 100 MHz