Optimization-Based Antenna Miniaturization Using Adaptively Adjusted Penalty Factors

• Main Authors: Marzieh Mahrokh, Slawomir Koziel
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Electronics
• Subjects: antenna miniaturization; compact antennas; EM-driven design; constrained optimization; penalty functions; constraint violations
• Online Access: https://www.mdpi.com/2079-9292/10/15/1751

The continuing trend for miniaturization of electronic devices necessitates size reduction of the comprising components and circuitry. Specifically, integrated circuit-antenna modules therein require compact radiators in applications such as 5G communications, implantable and on-body devices, or internet of things (IoT). The conflict between the demands for compact size and electrical and field performance can be mitigated by means of constrained numerical optimization. Evaluation of performance-related constraints requires expensive electromagnetic (EM) analysis of the system at hand; therefore, their explicit handling is inconvenient. A workaround is the penalty function approach where the primary objective (typically, antenna size) is complemented by additional terms quantifying possible constraint violations. The penalty coefficients that determine contributions of these terms are normally adjusted manually, which hinders precise control over antenna performance figures and often leads to inferior results in terms of achieved miniaturization rates. This paper proposes a novel algorithm featuring an automated adjustment of the penalty factors throughout the optimization process. Our methodology is validated using three broadband antenna structures. The obtained results demonstrate that the presented adaptive adjustment permits a precise control over the constraint violations while leading to better miniaturization rates as compared to manual penalty term setup.