External Antenna Gain and Bandwidth via Segmented Low-Frequency Coupling
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Solution Overview
Problem
Conventional external antenna structures face limitations in frequency band and are prone to impedance offset issues when trying to improve gain, particularly when extending low-frequency antennas.
Innovation Solution
The external antenna device incorporates a connecting carrier, elongated case, signal cable, and antenna structure with a matching module, low-frequency extending segment, and grounding segment, where the low-frequency extending segment is electrically coupled to the low-frequency portion, providing signal paths that are 0.375–0.625 times the wavelength of the low-frequency band, enhancing gain and frequency band capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the low-frequency antenna is integrally extended to increase length, then the gain is improved, but the frequency band is restricted and impedance offset occurs
Solution Approach 1:
The low-frequency antenna is divided into two separate segments: a low-frequency portion and a low-frequency extending segment arranged on opposite sides of the antenna segment. These segments are electrically coupled through capacitive coupling rather than direct physical connection. This segmentation allows each segment to contribute to the overall electrical length without requiring a single long continuous structure, thereby improving gain while maintaining frequency band adaptability and avoiding impedance offset issues.
2Power
If the low-frequency antenna is connected to the radiating portion, then the gain is improved, but the frequency band is restricted and impedance offset occurs
Solution Approach 1:
The low-frequency extending segment acts as an intermediary element that is electrically coupled to the low-frequency portion through capacitive coupling. This intermediary structure extends the electrical length of the low-frequency antenna path without creating a direct physical connection that would cause impedance mismatch. The capacitive coupling provides impedance transformation and matching, allowing the antenna to achieve higher gain while maintaining reliable impedance matching across the operating frequency band.
3Power
If the antenna length is increased for low-frequency operation, then the gain is improved, but the device size increases
Solution Approach 1:
Instead of extending the antenna length in a single linear direction, the low-frequency extending segment is arranged on the opposite side of the antenna segment from the low-frequency portion, creating a spatial distribution that effectively doubles the electrical path length without proportionally increasing the overall device footprint. This dimensional arrangement allows the antenna to achieve the required electrical length for low-frequency operation while maintaining a compact form factor.
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 increases the gain of the antenna structure and expands its frequency band operation beyond conventional limits, achieving a gain of at least 3 dBi while maintaining electrical coupling without impedance offset issues.
Implementation Method 1
The antenna structure is configured to be operated in a high-frequency band and a low-frequency band
Implementation Method 2
The high-frequency portion and the low-frequency portion are respectively and electrically connected to the feeding portion and the grounding segment via the matching module
Implementation Method 3
The low-frequency extending segment is arranged apart from the low-frequency portion with a gap and is electrically coupled to the low-frequency portion
Data Source
AI summary
An antenna structure of an external antenna device includes an elongated substrate, a grounding segment, an antenna segment, a matching module, and a low-frequency extending segment, the latter four of which are disposed on the substrate. The grounding segment and the low-frequency extending segment are respectively arranged on two opposite sides of the antenna segment. The antenna segment includes a feeding portion, a high-frequency portion, and a low-frequency portion. The high-frequency portion and the low-frequency portion are electrically connected to the feeding portion and the grounding segment via the matching module. The low-frequency portion and the low-frequency extending segment each has a signal path, and a total length of the two signal paths is 0.375˜0.625 times of a wavelength corresponding to a center frequency of a low-frequency band. The low-frequency extending segment is arranged apart from and is electrically coupled to the low-frequency portion.