Distributed Multiband Antenna Design for Mobile Devices
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Solution Overview
Problem
Existing multiband antennas for mobile devices face challenges in reducing size while maintaining performance, particularly in compliance with CTIA specifications, as they require larger volumes and heights to operate effectively across multiple frequency bands, leading to poor performance when proximate to phantom heads and hands.
Innovation Solution
A distributed multiband antenna configuration featuring a top-mounted PIFA for high-frequency operation and a bottom-mounted monopole antenna with a matching circuit for low-frequency operation, both mechanically and electrically separated to optimize performance in specific frequency bands, reducing the overall device size and improving compliance with CTIA regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single multiband antenna is used to operate across multiple frequency bands, then the device can support multiple bands, but the antenna requires larger volume and height which degrades performance when proximate to phantom heads and hands
Solution Approach 1:
The patent divides the single multiband antenna into multiple separate single-band antennas, each optimized for a specific frequency band. Each antenna element is independently designed and positioned, allowing the device to achieve multiband operation without requiring a large single antenna structure. This segmentation enables each antenna to be smaller while collectively covering multiple bands.
2Speed
If the antenna height is increased to improve lower frequency operation, then the antenna can resonate at lower frequencies, but the device thickness increases
Solution Approach 1:
The patent transitions from vertical antenna orientation to a planar configuration where antennas are arranged horizontally on the PCB. By changing the dimensional orientation from vertical (height-based) to horizontal (area-based), the antenna can achieve lower frequency resonance through increased planar dimensions rather than increased height, thus maintaining device thickness while improving low-frequency performance.
3Reliability
If multiple separate antennas are used for different frequency bands, then performance in each band can be optimized, but the device complexity increases
Solution Approach 1:
The patent combines multiple single-band antennas into a single integrated antenna system on one PCB. The multiple antenna elements are co-designed and co-positioned to work together, sharing common feed structures and ground planes. This merging approach maintains the performance benefits of separate optimized antennas while reducing overall system complexity compared to completely independent antenna systems.
Data Source
AI summary
A distributed multiband antenna intended for radio devices, and methods for designing manufacturing the same. In one embodiment, a planar inverted-F antenna (PIFA) configured to operate in a high-frequency band, and a matched monopole configured to operate in a low-frequency band, are used within a handheld mobile device (e.g., cellular telephone). The two antennas are placed on substantially opposing regions of the portable device. The use of a separate low-frequency antenna element facilitates frequency-specific antenna matching, and therefore improves the overall performance of the multiband antenna. The use of high-band PIFA reduces antenna volume, and enables a smaller device housing structure while also reducing signal losses in the high frequency band. These attributes also advantageously facilitate compliance with specific absorption rate (SAR) tests; e.g., in the immediate proximity of hand and head “phantoms” as mandated under CTIA regulations. Matching of the low-frequency band monopole antenna is further described.