Switched Multiband Antenna Harmonic Interference
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Solution Overview
Problem
Existing multiband antennas face challenges in achieving optimal performance across different frequency bands, particularly when the ratio of operating frequencies is an integer power of two, leading to radiation loss and harmonic interference, which is detrimental in energy-efficient autonomous devices.
Innovation Solution
A switched multiband antenna design with two switching means, one between the antenna strands and another on the strand to separate or connect sub-strands, allowing optimal tuning to both frequencies while preventing harmonic radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a multiband antenna is used to cover different frequency bands, then the space occupied by the antenna device is reduced, but the performance is never optimal for each working frequency
Solution Approach 1:
The antenna is divided into multiple separate strands (first strand, second strand, third strand) with different lengths, each optimized for specific frequency bands. Switching means are used to selectively connect different strands based on the operating frequency, allowing optimal performance for each frequency while sharing a common support structure and radio frequency access terminal.
2Reliability
If dedicated radio frequency antennas are installed for each frequency, then optimized performance for each frequency is achieved, but the space occupied and device complexity increase significantly
Solution Approach 1:
Multiple antenna strands are merged onto a single common support structure, sharing the same radio frequency access terminal and physical space. Switching means enable selective activation of different strands for different frequencies, combining the space efficiency of a single antenna structure with the performance benefits of multiple dedicated antennas.
3Device complexity
If the ratio of operating frequencies is an integer power of two, then frequency reconfiguration is simplified, but radiation loss and harmonic interference occur
Solution Approach 1:
The harmful second strand that causes radiation loss and harmonic interference is extracted from the active antenna configuration. Switching means are used to disconnect or leave floating the second strand when operating at frequencies where it would cause harm, while only the necessary first and third strands remain active for optimal performance.
4Adaptability or versatility
If the second antenna strand is left floating to enable first frequency operation, then the antenna can operate at the first frequency, but part of the radiation from the first strand is absorbed by the second strand
Solution Approach 1:
The antenna configuration is made dynamic through switching means that can change the electrical connection state of different strands based on the operating frequency. The second strand can be electrically connected, left floating, or disconnected depending on which frequency band is active, optimizing performance for each frequency while minimizing energy loss.
Data Source
Figure 1~2
Figure 3
AI summary
This multiband switched radio frequency antenna (101) is configured to radiate and/or receive radio frequency signals on at least a first and a second operating frequency, the ratio of which is substantially equal to an integer power of two. The antenna body (102) comprises at least a first and a second antenna element (111, 112). The antenna includes at least a first and a second switching means (113, 114) arranged respectively between the first and second elements (111, 112) and between two sub-elements (1121, 1122) of the second element (112). The first and second switching means (113, 114) are configured to be actuated simultaneously and analogously. The length of the first antenna sub-element (1121) differs by a fraction of an integer power of two of the wavelength associated with the first operating frequency.The antenna (101) is tuned to the first operating frequency when the first and second switching means (113, 114) are in the first operating mode, and tuned to the second frequency when the first and second switching means (113, 114) are in the second operating mode.