Bypassable RF Filter Using Adjustable Electrical Length Routing

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Solution Overview

Problem

Conventional switching techniques, such as solid-state switches and electromechanical relays, are not ideal for bypassing RF filters in base station antennas due to high current consumption and reliability issues, and they can introduce spurious signals that interfere with adjacent RF systems.

Innovation Solution

A device with a bypassable RF filter that uses an adjustable-length RF transmission line and electronic components like phase shifters or PIN diodes to change the electrical length, allowing RF signals to bypass the filter in certain modes of operation without using solid-state switches or electromechanical relays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional switching techniques (solid-state switches or electromechanical relays) are used to bypass RF filters, then the filter can be bypassed, but high current consumption and reliability issues occur

Engineering Contradiction:

Improveswitching reliabilityVSAvoidcurrent consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces electromechanical relays and solid-state switches with a transmission line of adjustable electrical length. This substitution eliminates the need for active switching components that consume power or have reliability issues, using instead a passive RF-based mechanism controlled by phase shifters or PIN diodes to achieve filter bypassing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the electrical length parameter of the transmission line to control signal routing. By adjusting the electrical length between 0 and λ/4 (where λ is the wavelength at the operating frequency), the system transitions between filter-passing and filter-bypassing modes without requiring power-consuming switches.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If solid-state switches are used for bypassing, then switching is achieved, but spurious signals are introduced that interfere with adjacent RF systems

Engineering Contradiction:

Improveswitching capabilityVSAvoidspurious signals

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent replaces solid-state switches with a transmission line-based bypass mechanism. This substitution eliminates the spurious signal generation inherent in solid-state switching while maintaining the ability to route signals around the filter when needed, using instead RF-based phase control or PIN diode switching that does not generate harmful emissions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If an RF filter is used for a particular application, then filtering performance is improved, but the filter cannot be bypassed for other applications

Engineering Contradiction:

Improvefiltering performanceVSAvoidapplication flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent makes the RF filter system dynamic by introducing an adjustable electrical length transmission line that can change its characteristics based on operating conditions. This allows the system to adapt between filtered and unfiltered modes, enabling the same antenna to serve multiple applications with different filtering requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent creates a universal RF path that can function in multiple modes: passing signals through the filter for applications requiring frequency selection, or bypassing the filter for applications requiring full bandwidth. The adjustable transmission line enables a single system to serve both filtered and unfiltered applications.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables efficient routing of RF signals through or around the filter based on electrical length adjustments, reducing interference and improving reliability by avoiding direct current consumption and spurious signal introduction, thus enhancing the operational flexibility of base station antennas.

Implementation Method 1

an adjustable-length RF transmission line that is coupled to the bypassable RF filter... configured to change an electrical length of the adjustable-length RF transmission line between a first length and a second length

Methodology Applied

Scientific EffectElectrical length adjustment:

Implementation Method 2

The electronic component may be a phase shifter or a PIN diode

Methodology Applied

Scientific EffectPhase shifting:

Implementation Method 3

The electronic component may be a phase shifter or a PIN diode

Methodology Applied

Scientific EffectPIN diode effect: Diode

Data Source

PatentUS11770164B2Bypassable radio frequency filters

Publication Date: 2023.09.26 COMMSCOPE ITAL SRL

AI summary

Devices having bypassable radio frequency (RF) filters are provided. A device includes a bypassable RF filter and an adjustable-length RF transmission line that is coupled thereto. Moreover, the device includes a component that is coupled to the adjustable-length RF transmission line and is configured to change an electrical length of the adjustable-length RF transmission line between a first length and a second length. Related methods of bypassing the bypassable RF filter are also provided.