Overlapping Antenna Feed Circuit for Analog Isolation Cancellation
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Solution Overview
Problem
In mobile computing devices, achieving sufficient antenna isolation between multiple integrated wireless technologies, such as WiFi and LTE, is challenging due to limited space and the absence of guard bands between frequency bands, making current RF filters unsuitable for providing adequate co-existence performance.
Innovation Solution
The technique involves a pair of antennas that partly share the same volume with overlapping configurations and an analog compensation system using passive components like RF switches, capacitors, and inductors to enhance isolation, providing more than 40 dB RF isolation without the need for RF filters like SAW filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF filters such as SAW filters are used to provide antenna isolation, then antenna isolation is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for complex RF filters by using a simplified antenna feed system with passive components. The solution takes out the harmful dependency on SAW filters while maintaining isolation performance through alternative means (feed network design with resistors, capacitors, and inductors).
Solution Approach 2:
The patent replaces expensive RF filters with inexpensive passive components (resistors, capacitors, inductors) that can be easily integrated into the feed system. These simple components achieve the isolation function at lower cost and complexity while being easily replaceable or adjustable.
2Reliability
If RF filters are used to provide antenna isolation, then antenna isolation is improved, but frequency separation requirements increase
Solution Approach 1:
The patent uses passive components (resistors, capacitors, inductors) in the feed system whose values can be adjusted to optimize performance for different frequency bands. This allows the same antenna structure to work across multiple bands (sub-6 GHz, mmWave) without requiring different filter designs, achieving frequency adaptability through parameter tuning.
Solution Approach 2:
The antenna feed system design achieves multi-functionality by using a universal passive component-based approach that works across different frequency bands and antenna configurations. The same feed network topology can serve both sub-6 GHz and mmWave bands, eliminating the need for band-specific filters.
3Volume of moving object
If antennas are placed closer together to reduce device size, then device form factor is improved, but antenna isolation deteriorates
Solution Approach 1:
The patent introduces passive components (resistors, capacitors, inductors) as intermediary elements in the antenna feed system that mediate between closely spaced antennas. These intermediaries provide isolation between antennas while allowing them to be positioned close together, enabling compact device design without sacrificing isolation performance.
Solution Approach 2:
The patent moves the isolation function from the spatial domain (physical distance between antennas) to the circuit domain (impedance matching and signal conditioning through passive components). By addressing isolation through electrical rather than physical means, the antennas can be placed closer together in space while maintaining isolation through circuit design.
Data Source
AI summary
Techniques are disclosed for providing isolation between a pair of partially overlapping antennas. An example electronic device includes a first antenna coupled to a first transceiver through a first signal path comprising a first feed, and a second antenna coupled to a second transceiver through a second signal path comprising a second feed. The first antenna and second antenna partially overlap. The example electronic device also includes compensation circuitry coupled to the first signal path and the second signal path and configured to generate a compensation signal that provides analog cancellation of an interference signal received at the second antenna from the first antenna.