Microstrip Cable Tap Ripple Reduction

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Solution Overview

Problem

Outdoor cable taps in cascaded networks suffer from significant ripple and insertion loss due to the cascading effect, which worsens as frequency increases, limiting data transport capabilities and requiring costly re-spacing or amplifier additions.

Innovation Solution

A microstrip directional coupler is used in a cable tap device, eliminating the need for a power choke and incorporating a tilt compensating circuit with resistive, inductive, and capacitive elements to control frequency response and adapt tap loss, ensuring lower insertion loss and balanced frequency response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If traditional ferrite core directional couplers are used in outdoor cable taps, then the device can handle power transmission, but significant ripple and insertion loss occur due to the cascading effect in cable networks

Engineering Contradiction:

Improveinsertion lossVSAvoiddevice complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent changes the fundamental operating parameters by transitioning from a ferrite core directional coupler to a microstrip directional coupler. This parameter change enables the system to achieve lower insertion loss and reduced ripple in cascaded networks, as the microstrip design inherently provides better frequency response characteristics and lower loss when multiple taps are cascaded together.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional ferrite core mechanical/physical structure with a microstrip transmission line structure. This substitution eliminates the need for bulky ferrite materials and complex power handling mechanisms, achieving both reduced insertion loss and simplified device complexity through integration on a circuit board.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If more outdoor taps are cascaded in series to expand network coverage, then network reach is improved, but ripple in frequency response is amplified making signal quality unacceptable

Engineering Contradiction:

Improvenetwork coverageVSAvoidsignal quality

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

By changing to a microstrip directional coupler design, the patent achieves parameter improvements in insertion loss and frequency response flatness. This allows more taps to be cascaded in series while maintaining acceptable signal quality, thereby expanding network coverage without sacrificing reliability.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If higher frequencies are used to transport more data and programs, then data capacity is improved, but loss in coaxial cables increases significantly reducing signal levels at the end of the line

Engineering Contradiction:

Improvedata transport capacityVSAvoidsignal loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The microstrip directional coupler design changes the loss characteristics of the cable tap system. By reducing insertion loss through the microstrip architecture, the patent enables higher frequencies to be used for data transport while compensating for the increased coaxial cable loss, thereby maintaining adequate signal levels at the end of the line.

Inventive Principle:

Principle #35Parameter changes

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

The solution reduces insertion loss, minimizes ripple, and maintains consistent tap loss across frequencies, enhancing data transport capabilities and reducing network alignment complexities while avoiding the limitations of ferrite core directional couplers.

Implementation Method 1

a directional coupler disposed on a through electrical path between an input and an output, the directional coupler arranged to communicate with a splitter device

Methodology Applied

Scientific EffectElectromagnetic signal propagation: Electromagnetic Induction

Implementation Method 2

a feedback path comprising resistive, inductive and capacitive elements so as to control frequency response

Methodology Applied

Scientific EffectResistive element: Electrical Resistance

Implementation Method 3

a feedback path comprising resistive, inductive and capacitive elements so as to control frequency response

Methodology Applied

Scientific EffectInductive element: Inductor

Implementation Method 4

a feedback path comprising resistive, inductive and capacitive elements so as to control frequency response

Methodology Applied

Scientific EffectCapacitive element: Capacitance

Implementation Method 5

a tilt compensating means or circuit may be disposed between the microstrip directional coupler and the splitter device to precisely adapt the tap loss to counteract losses in coaxial cables

Methodology Applied

Scientific EffectSignal attenuation compensation:

Data Source

PatentUS10103420B2Cable tap

Publication Date: 2018.10.16 TECHNETIX

AI summary

There is provided a cable tap device for a CATV network comprising a microstrip directional coupler on an electrical path between an input and an output and arranged to communicate with a splitter device associated with a plurality of tap ports. A tilt compensating circuit is disposed between the microstrip directional coupler and the splitter device. A feedback path comprising resistive, inductive and capacitive elements connects an isolated port of the microstrip directional coupler to that part of the electrical path between the input and the input port of the microstrip directional coupler.