News Release

UESTC researchers unveil ultra-wideband, low-profile antenna for airborne applications

A low-profile, omnidirectional antenna design with a 12:1 impedance bandwidth could advance modern aircraft communication systems

Peer-Reviewed Publication

Journal of Electronic Science and Technology

Ultra-wideband, low-profile antenna for next-generation aircraft.

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The ultra-wideband, omnidirectional circular ring antenna has a height of 0.047 times the low-frequency wavelength and a width of 0.19 times the wavelength, offering an impedance bandwidth of 12:1. This compact design shows promising potential for integration into aircrafts without compromising stealth or aerodynamic efficiency.

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Credit: Alert5 from Openverse Image Source Link: https://openverse.org/image/4cfd733c-6604-48a6-8edb-4616dfea40f8?q=Chengdu+J-20&p=2

As stealth capabilities and aerodynamic performance become essential, modern combat aircrafts are being designed with flatter profiles to minimize their radar signature and improve aerodynamic efficiency. These aircrafts feature a flying wing design that resembles a flat plate and a tailless configuration, significantly reducing the surface area detectable by radar. However, these sleek designs pose challenges when integrating communication and navigation systems.

Traditional antennas, which are bulky and protrude from the aircraft, can be easily detected by radar. To maintain both stealth and aerodynamic performance, compact antennas that seamlessly integrate into the aircraft’s structure are increasingly necessary. Currently, antennas as small as 5 mm can be built into the surface of aircrafts. However, these antennas typically operate within a narrow frequency range of 2.3 GHz – 2.5 GHz. To cover a wider range (150 MHz–600 MHz), the antenna’s height needs to be increased to 0.39 times the wavelength, making it much larger than the original 5 mm size.

In a recent study published in the Journal of Electronic Science and Technology, researchers from the Southwest China Institute of Electronic Technology and the University of Electronic Science and Technology of China (UESTC) introduced an omnidirectional circular ring antenna that is both ultra-wideband and low-profile. Led by Associate Professor Feng Yang of UESTC, the research team presented an antenna with a profile height of just 0.047 times the low-frequency wavelength, making it significantly smaller and capable of covering a broader frequency range. This paper was made available online on November 7, 2024, and was published in Volume 22, Issue 4 of the journal on December 1, 2024.

“We propose an airborne ultra-wideband circular ring conformal array antenna based on the typical tightly coupled ultra-wideband long slot element and traditional miniaturization methods of omnidirectional antennas,” explains Dr. Yang.

The research team achieved miniaturization by extending the current path of the antenna, effectively making it electrically longer than its physical size. The design features two tightly coupled dipole antennas arranged in a circular pattern, with the H-plane (corresponding to the magnetic field) aligned with the array's direction. Each antenna is designed with a long slot opening, which shapes the current flow and enables the antenna to operate across a broad frequency range. The elements are fed with equal in-phase power, ensuring consistent signal strength across all elements.

To achieve a low-profile design, the antenna uses two elements connected with a power divider along the E-plane (electric field) direction. However, using only two elements leads to edge effects, such as current loss at the edges and impedance mismatch. To resolve this, they incorporated a short-circuit wall, which reflects electric fields like a mirror and helps to control the current flow along the antenna. They also placed lumped resistors in the gaps of the wall to absorb edge reflected waves.

To further reduce ground reflection interference, the researchers positioned a resistive frequency-selective surface between the antenna and the metal ground. Simulations showed that this surface absorbs over 30% of the reflected energy, especially at higher frequencies where interference is most severe, thereby improving overall performance.

This results in a highly compact, ultra-low-profile omnidirectional circular array with eight elements, featuring a height of only 0.047 times the low-frequency wavelength and a lateral diameter of 0.19 times the wavelength. The antenna operates across a broad frequency range, achieving an impedance bandwidth close to 12:1 while maintaining an active voltage standing wave ratio (VSWR) consistently below 3, indicating efficient performance with minimal energy loss. Additionally, it also ensures good omnidirectional radiation characteristics, with gain patterns controlled within 3 dB across the entire operational bandwidth, making it ideal for multifunctional airborne antenna applications.

“The proposed tightly coupled ultra-wideband low-profile omnidirectional circular ring conformal array antenna exhibits good performances such as ultra-wideband, low-profile, vertical polarization, and high-gain omnidirectional radiation, showing promising potential in airborne antenna applications,” says Dr. Yang.

Overall, this study presents a compact, high-performance antenna designed to seamlessly integrate into modern stealth aircraft, enabling efficient communication and navigation without compromising radar invisibility or aerodynamic performance.

 

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Reference

DOI: 10.1016/j.jnlest.2024.10028


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