Multiband Antenna Isolation via Short-Circuited Section
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Solution Overview
Problem
Designing compact, efficient multiband antennas for mobile terminals is challenging due to limited space, leading to close proximity and coupling between antennas, which reduces their efficiency and diversity performance in noise-limited environments.
Innovation Solution
A multiband antenna system with a short-circuited section between a UMTS antenna and a UMTS receive diversity antenna provides large electrical isolation, using well-isolated antennas that can be tuned independently, allowing for efficient operation across GSM, CDMA, WLAN, and Bluetooth protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If antennas are placed close together in limited space, then the device size is reduced, but the coupling between antennas increases and efficiency decreases
Solution Approach 1:
The antenna system is divided into multiple independent antenna elements (first antenna, second antenna, third antenna) with distinct radiators and feed points. Each antenna can be independently designed and tuned, allowing them to be placed in close proximity while maintaining individual performance characteristics and reducing mutual coupling effects.
Solution Approach 2:
Each antenna element is designed with specific local characteristics - the first antenna has a radiator optimized for its frequency range, the second antenna has a different radiator configuration for its overlapping frequencies, and the third antenna has a radiator with sections positioned to operate at lower frequencies. This local optimization allows each antenna to maintain efficiency despite close spacing.
2Volume of moving object
If multiple antennas are integrated in small volume, then device compactness is improved, but diversity performance deteriorates due to high correlation
Solution Approach 1:
The diversity antenna system is segmented into multiple independent elements (second antenna and third antenna) with distinct radiators. The third antenna's radiator is divided into sections with specific positioning, allowing the system to achieve low correlation between diversity elements while maintaining compact form factor.
Solution Approach 2:
The antennas are arranged in a three-dimensional configuration within the compact device volume. The third antenna's radiator sections are positioned at different locations and orientations relative to the other antennas, creating spatial separation in multiple dimensions that reduces signal correlation while maintaining overall compactness.
3Productivity
If antennas operate at overlapping frequency ranges, then spectral efficiency is improved, but interference between antennas increases
Solution Approach 1:
The system uses segmented antenna elements with distinct radiators - the first antenna for its frequency range, the second antenna with different radiator configuration for overlapping frequencies, and the third antenna with sectioned radiator for lower frequencies. This segmentation allows independent impedance matching and frequency tuning, reducing interference while maintaining spectral efficiency.
Solution Approach 2:
Each antenna element is locally optimized for its specific frequency operation. The radiators have different geometries and configurations tailored to their respective frequency ranges, allowing them to operate at overlapping frequencies with minimal mutual interference through localized electromagnetic field optimization.
Data Source
AI summary
An antenna system for use in a communications device, such as a mobile phone. The antenna system has a multiband GSM antenna operating at GSM850, GSM900, GSM 1800 and GSM 1900 that has a short-circuited section located between a separate UMTS antenna and a UMTS receive diversity antenna. As such, large electrical isolation between the two UMTS antennas can be achieved. The UMTS antennas can be short-circuited microstrip loop antennas, IFA, PIFA, ILA or PILA antennas. These antennas are well-isolated antennas instead of coupled antennas. As such, the diversity antenna is well isolated from the main antenna despite its close proximity to the main antenna. Well-isolated antennas have little mutual coupling and, therefore, are easier to design than coupled antennas, because isolated antennas can be tuned independently from each other.