Monopole Antenna Coupling Optimization for Radiation Efficiency
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Solution Overview
Problem
Conventional antenna apparatuses face inefficiencies in radiation efficiency due to the lack of an antenna switch, particularly between the second and third antennas, which are capacitively coupled for impedance matching but not optimized for improved efficiency.
Innovation Solution
The antenna apparatus includes a monopole type first and second antenna element with specific feed points and lengths, where the distance between the feed points and the lengths of the antenna elements are optimized to enhance radiation efficiency by adjusting the coupling strength between the elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second antenna is capacitively coupled to the third antenna for impedance matching, then the impedance matching is improved, but the radiation efficiency deteriorates
Solution Approach 1:
A ground plane is introduced as an intermediary element between the second antenna and the third antenna. The ground plane serves as a mediator that enables impedance matching through capacitive coupling while simultaneously improving radiation efficiency by providing a reference potential and enhancing the overall antenna system performance.
Solution Approach 2:
The invention optimizes specific parameters including the distance between the second antenna and ground plane (0.05λ to 0.15λ), the distance between the third antenna and ground plane (0.10λ to 0.20λ), and the width of the ground plane (0.20λ to 0.40λ). By carefully adjusting these parameters, the system achieves both good impedance matching and improved radiation efficiency.
2Device complexity
If multiple antennas are provided on a substrate without antenna switches, then the device complexity is reduced, but the radiation efficiency deteriorates
Solution Approach 1:
The ground plane acts as a mediator that enables efficient electromagnetic coupling between multiple antennas without requiring complex switching mechanisms. This intermediary structure allows the system to maintain low complexity while achieving good radiation efficiency through capacitive coupling and proper grounding.
Solution Approach 2:
The ground plane serves multiple functions simultaneously: it provides impedance matching for capacitive coupled antennas, improves radiation efficiency, acts as a reference potential for monopole antennas, and enables compact multi-antenna integration. This multi-functionality reduces the need for additional components like antenna switches.
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
This configuration improves radiation efficiency by optimizing the coupling between the antenna elements, achieving higher efficiency compared to when used alone and maintaining similar return loss, thereby enhancing the overall performance of the antenna apparatus.
Implementation Method 1
A gap G is interposed between the second antenna and the third antenna on the substrate such that the second antenna is capacitively coupled to the third antenna
Data Source
AI summary
An antenna apparatus includes a ground plane having an edge; a monopole type first antenna element having a first feed point and configured to communicate at a first frequency; and a monopole type second antenna element having a second feed point and configured to communicate at a second frequency, the second antenna element extending from the second feed point in a direction away from the edge. An end portion of the first antenna element is arranged closer to the ground plane than an end portion of the second antenna element is. A length of an interval between the first feed point and the second feed point is in a range of from 0.25-fold to 0.7-fold of an electrical length of a first wavelength at the first frequency. A length of the second antenna element is a length in a range of from 0.15-fold to 0.55-fold of the electrical length.