Abstract
A novel approach for improving antenna bandwidth is described using a 6-element Yagi-Uda array as an example. The new approach applies Central Force Optimization, a deterministic metaheuristic, and Variable Z0 technology, a novel, proprietary design and optimization methodology, to produce an array with 33.09% fractional impedance bandwidth. This array’s performance is compared to its CFO-optimized Fixed Z0counterpart, and to the performance of a 6-ele- ment Dominating Cone Line Search-optimized array. Both CFO-optimized antennas exhibit better performance than the DCLS array, especially with respect to impedance bandwidth. Although the Yagi-Uda antenna was chosen to illustrate this new approach to antenna design and optimization, the methodology is entirely general and can be applied to any antenna against any set of performance objectives.
Highlights
This note describes a novel approach to improving antenna bandwidth using a six-element Yagi-Uda array as an example
The Yagi-Uda antenna was chosen to illustrate this new approach to antenna design and optimization, the methodology is entirely general and can be applied to any antenna against any set of performance objectives
This paper provides an example of applying Central Force Optimization and Variable Z0 sm * technology to the design of a wideband Yagi-Uda array
Summary
This note describes a novel approach to improving antenna bandwidth using a six-element Yagi-Uda array as an example. Developed more than 85 years ago [1,2], the “Yagi” still is widely used, but it is inherently narrowband, to quote: “Usually Yagi-Uda arrays have low input impedance and relatively narrow bandwidth (on the order of about 2%)” [3, p.396]. Modern well-designed Yagis achieve greater bandwidth, on the order of 5% [4] to more than 15% [5], but these bandwidths still are far below the requirements of many wireless systems. The Federal Communications Commission, for example, defines an Ultra Wideband (UWB) antenna as having a fractional impedance bandwidth (IBW) of at least 20%, or an absolute bandwidth of 500 MHz [6, p.15]. The CFO-VZ0 Yagi achieves a very robust IBW of 33.09% for VSWR ≤ 2:1
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