Antenna isolation method using sub-array structure with soft-surface for Tx/Rx separated FDD hybrid beamforming system

Abstract

The FDD method is normally used for the stability of the Tx and the Rx links in a fast-varying channel. It is required to physically separate the Tx and Rx arrays for independent Tx and Rx beam control. In this system, it is important to reduce the Tx self-interference (SI) that causes the problem of active element saturation and ADC dynamic range in the Rx beamformer. To suppress Tx SI, we proposed two simple techniques. The first is the general soft-surface which attenuates the surface current flow from the Tx tile array to the Rx array. The second is the sub-array structure of the Rx hybrid beamforming system. Based on the Cauchy–Schwartz inequality, the electrical sum by the sub-array acts as a destructive interference of the complex SI signals, and it can be shown as an additional isolation effect. The proposed idea was validated through measurement.

KEYWORDS:

• Word
• antenna isolation
• self-interference (SI)
• sub-array
• soft-surface

Acknowledgements

This work was supported by Agency for Defense Development (ADD) under Grant (UC180006ED).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Agency for Defense Development (ADD) [grant number UC180006ED].

Notes on contributors

Young-Dam Kim

Young-Dam Kim is currently a senior researcher at the Agency for Defense Developement (ADD). His interests are electromagnetic numerical analysis and active phased array antenna signal processing.

Taehwan Joo

Taehwan Joo is currently a senior researcher at the Agency for Defense Developement (ADD). His interests are RF transceiver and data link system.

Chan-Ho Hwang

Chan-Ho Hwang is currently a senior researcher at the Agency for Defense Developement (ADD). His interests are wireless communication system and signal processing.

Kichul Kim

Kichul Kim is currently a senior researcher at the Agency for Defense Developement (ADD). His interests are RF circuit/power amplifier and high-frequency technique for communication.

Jae-Soo Jung

Jae-Soo Jung is currently a principal researcher at the Agency for Defense Developement (ADD). He is currently the team leader of the communication and high-frequency team in ADD.