RF Coupling Apparatus for Signal Leakage Isolation

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Solution Overview

Problem

In wireless communication systems where a transmitting unit and a receiving unit share an antenna, existing technologies fail to effectively isolate the leakage of the transmitting signal, leading to deteriorated receiving signal performance, especially in RFID systems where the intensity of the transmitting signal overwhelms the receiving signal.

Innovation Solution

A coupling apparatus using a four-port circuit with a variable attenuator is employed to isolate and control the leakage of the transmitting signal, comprising a through path and isolation paths between ports, with a subtracter to remove the leakage signal from the receiving signal, and a control unit to adjust the attenuation value based on measured signal strength indicators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a circulator is used to isolate transmitting signal leakage, then isolation performance is improved, but device size and cost increase significantly at frequencies below 1 GHz

Engineering Contradiction:

Improveisolation performanceVSAvoiddevice size and cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the harmful transmitting signal leakage from the receiving signal path by using a directional coupler to separate the signals. The directional coupler identifies and extracts the forward traveling transmitting signal, removing it from the mixed signal that would otherwise be received, thereby achieving isolation without requiring a large circulator.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a directional coupler as an intermediary device between the antenna and the receiving unit. This intermediary selectively couples only the forward traveling transmitting signal while allowing the receiving signal to pass through to the receiving unit, thereby mediating the isolation between transmitting and receiving paths.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a directional coupler is used to isolate transmitting signal leakage, then isolation performance is improved, but complete isolation cannot be achieved due to signal leakage

Engineering Contradiction:

Improveisolation performanceVSAvoidresidual leakage signal

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful residual leakage signal into a beneficial cancellation signal by generating a reverse traveling wave that is equal in magnitude but opposite in phase. This cancellation signal is injected into the receiving path to destructively interfere with and cancel the residual leakage, thereby eliminating the harmful effect.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies preliminary anti-action by generating a cancellation signal in advance that is designed to counteract the expected residual leakage signal. The cancellation signal is prepared with the correct amplitude and phase relationship before being injected into the receiving path, ensuring that the harmful leakage is neutralized before it can degrade the receiving signal.

Inventive Principle:

Principle #9Preliminary anti-action

3Power

If transmitting signal intensity is increased to improve transmission range, then transmission performance is improved, but receiving signal quality deteriorates due to increased leakage

Engineering Contradiction:

Improvetransmitting signal intensityVSAvoidreceiving signal quality

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent extracts the harmful transmitting signal leakage from the receiving signal path using a directional coupler. By separating the forward traveling transmitting signal from the mixed signal, the system can maintain high transmitting power without the leakage degrading the receiving signal quality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful effect of high-power transmitting leakage into a beneficial cancellation mechanism. The system generates a reverse traveling wave that cancels the leakage, allowing high transmitting power to be used while maintaining receiving signal quality through active cancellation of the harmful leakage component.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS9160047B2Coupling apparatus for dividing receiving and transmitting signals and control method thereof

Publication Date: 2015.10.13 INTELLECTUAL DISCOVERY CO LTD

AI summary

The present invention is directed to a coupling apparatus for dividing a radio frequency (RF) transmitting signal and an RF receiving signal in a transceiver with a transmitting unit and a receiving unit sharing an antenna, comprising: a four-port circuit having ports 1-4; a through path formed between the port 1 and the port 2; a first signal input to the port 1 being coupled to the port 4; a second signal input to the port 2 being coupled to the port 3; an isolation path formed between the port 1 and the port 3 and between the port 2 and the port 4; an attenuator attenuating a signal output from the port 4; and wherein the RF transmitting signal is input to the port 1, the RF receiving signal is input to the port 2, and outputs of the port 3 are provided to the receiving unit.