Compact Omnidirectional Antenna Structure for Wireless Access Points
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Solution Overview
Problem
Designing a small-size, omnidirectional antenna structure for wireless access points is challenging due to indoor signal reflection and multipath fading, requiring effective coverage of various transmission directions within limited space.
Innovation Solution
The antenna structure incorporates a dielectric substrate with multiple feeding elements, a balun structure, and radiation elements arranged in a loop configuration, with specific coupling gaps and resonant paths optimized for frequency bands from 5150 MHz to 5850 MHz, minimizing size while ensuring omnidirectional radiation patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional antenna designs are used, then the antenna can provide omnidirectional radiation pattern, but the antenna size is large and occupies excessive space in wireless access points
Solution Approach 1:
The balun structure is nested within the loop structure formed by the radiation elements. The central ground element is surrounded by connection elements that are coupled to the radiation elements, creating a compact nested arrangement that reduces overall antenna volume while maintaining omnidirectional radiation capability through the loop configuration
Solution Approach 2:
The antenna structure transitions from planar to three-dimensional configuration by positioning feeding elements on one side of the dielectric substrate and radiation elements on the other side, with vertical coupling gaps creating spatial separation. This dimensional arrangement allows compact footprint while preserving omnidirectional radiation patterns
2Volume of moving object
If antenna size is reduced to fit limited space, then space utilization improves, but radiation efficiency and omnidirectional performance deteriorate
Solution Approach 1:
The resonant paths are designed with specific length requirements (integral multiples of 0.25 wavelength) to maintain resonance at operating frequencies despite reduced physical size. The coupling gaps between feeding elements and radiation elements are optimized to specific dimensions to ensure efficient energy transfer while keeping the overall antenna compact
Solution Approach 2:
The balun structure nested within the loop structure enables compact configuration that maintains adequate electrical length for resonance while reducing physical volume. The nested arrangement ensures proper current distribution and impedance transformation without sacrificing radiation efficiency
3Adaptability or versatility
If multiple feeding elements and connection elements are added to achieve omnidirectional coverage, then radiation pattern quality improves, but device complexity increases
Solution Approach 1:
The central ground element serves multiple functions: it acts as the reference plane for the balun structure, provides the return path for both feeding elements, and forms part of the resonant circuits. The connection elements simultaneously provide impedance transformation and couple both feeding elements to the radiation elements, reducing the need for separate components
Solution Approach 2:
The balun structure and feed network are merged into a single integrated configuration where the central ground element and connection elements perform both balancing and feeding functions. The loop structure formed by radiation elements combines multiple radiation functions into a unified omnidirectional pattern without requiring separate antenna elements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a 75% reduction in antenna size compared to conventional designs, maintaining wide frequency band coverage and high radiation efficiency with an almost omnidirectional horizontally-polarized radiation pattern, suitable for wireless access points.
Implementation Method 1
a first resonant path is formed from the feeding point through the first feeding element, the first via element and the first connection element to the central opening of the central ground element. A second resonant path is formed from the feeding point through the second feeding element, the second via element and the third connection element to the central opening of the central ground element. The length of each of the first resonant path and the second resonant path is an integral multiple of 0.25 wavelength of the operation frequency band
Data Source
AI summary
An antenna structure includes a first feeding element, a second feeding element, a balun structure, a first radiation element, a second radiation element, a third radiation element, a fourth radiation element, a fifth radiation element, a sixth radiation element, and a dielectric substrate. The balun structure includes a central ground element, a first connection element, a second connection element, a third connection element, and a fourth connection element. The first connection element and the third connection element partially surround the central ground element. A first coupling gap is formed between the fifth radiation element and the first radiation element. A second coupling gap is formed between the fifth radiation element and the third radiation element. A third coupling gap is formed between the sixth radiation element and the second radiation element. A fourth coupling gap is formed between the sixth radiation element and the fourth radiation element.