Electrically Small Permeable Antennas

Conformal magnetically permeable antennas, are uniquely capable of achieving a high gain-bandwidth product when embedded in conductive surfaces such as aircraft skins. This makes them especially valuable for DoD applications at UHF frequencies and below, where conventional conformal antennas require significant spacing from the platform to perform effectively. While these antennas have been successfully demonstrated on larger platforms at VHF to UHF frequencies, new interest lies in electrically small platforms, such as UAVs operating in the HF (5–50 MHz) range. Because these platforms are much smaller than a half wavelength, only electrically small antennas (about 1/20 of a wavelength across) are practical.

 

Researchers at Arizona State University have developed an innovative antenna feeding and matching circuit approach that enhances the performance and impedance compatibility of electrically small permeable antennas, helping them achieve superior performance at low frequencies (UHF and below). A novel feed structure is introduced for electrically small conformal magnetically permeable antennas, improving radiation impedance and resistance to connection imperfections. It includes a unique matching circuit transforming antenna impedance to a standard 50-ohm, preserving a large Gain-Bandwidth Product, ideal for constrained spaces such as UAVs operating in UHF and HF frequency ranges. With these antennas, instantaneous bandwidths ranges are attained with Gains that exceed the Gain of a comparable conventional metal-and-dielectric antenna by more than +15dB, even when forced to fit into the same electrically small conformal form factor.

 

This groundbreaking feed and matching circuit design enhance bandwidth and efficiency of electrically small permeable antennas for military and UAV applications.