Inductively Shorted Bicone Dipole Antenna for Bandwidth

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Solution Overview

Problem

Bicone fed antenna systems face challenges in extending their low frequency response, particularly in achieving improved performance across all frequency ranges, with existing designs experiencing bandwidth loss and increased VSWR due to tight coupling between resonant elements.

Innovation Solution

A combined bicone and dipole antenna configuration is introduced, where the bicone section is converted into a bicone fed dipole with increased height and a pitch angle adjustment, and inductive shorts are strategically placed along the circumferential perimeter to maintain low frequency response and minimize coupling, allowing for a smooth taper and reduced antenna diameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the bicone and dipole sections are tightly coupled to reduce antenna diameter, then the antenna size is reduced, but bandwidth loss occurs and VSWR increases

Engineering Contradiction:

Improveantenna diameterVSAvoidbandwidth and VSWR performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

Inductive shorts are introduced as intermediary elements positioned between the bicone and dipole sections. These shorts provide magnetic coupling that allows the sections to be electrically connected while maintaining physical separation, thereby reducing direct capacitive coupling and minimizing bandwidth loss and VSWR increases that would otherwise occur with tight coupling

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The antenna transitions from a two-dimensional planar configuration to a three-dimensional structure by positioning the bicone and dipole sections at different spatial locations and using inductive shorts to connect them. This dimensional change allows the sections to be closer together physically while maintaining electrical isolation, thus reducing antenna diameter without sacrificing performance

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the bicone section is lengthened to lower cut-in frequency, then low frequency response is improved, but the antenna height increases

Engineering Contradiction:

Improvelow frequency responseVSAvoidantenna height

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The antenna is segmented into distinct bicone and dipole sections that can be independently optimized. The bicone section handles the low frequency response requirement while the dipole section manages the overall length, allowing the total antenna height to be controlled while achieving the desired low frequency performance through the combined structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cut-in frequency is lowered by changing the electrical parameters of the bicone section, specifically by adjusting its dimensions and coupling characteristics through the inductive shorts. This allows the low frequency response to be improved without proportionally increasing the physical height of the entire antenna structure

Inventive Principle:

Principle #35Parameter changes

3Reliability

If inductive shorts are added to maintain low frequency response, then bandwidth is enhanced, but device complexity increases

Engineering Contradiction:

ImprovebandwidthVSAvoidantenna structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The inductive shorts serve multiple functions simultaneously: they provide the necessary magnetic coupling to extend bandwidth, they maintain the electrical connection between bicone and dipole sections, and they enable the antenna to achieve resonant frequencies across a broader range. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity

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

The modified antenna design effectively lowers the cut-in frequency, maintains low VSWR, and enhances bandwidth by decoupling the bicone and dipole sections, resulting in improved performance across the frequency spectrum while maintaining a constant characteristic impedance.

Implementation Method 1

inductive shorts are strategically placed along the circumferential perimeter to maintain low frequency response and minimize coupling

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

The shorter element with a resonance frequency above the area has a capacitive impedance of negative phase approaching −90 degrees

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS9077080B1Inductively shorted bicone fed tapered dipole antenna

Publication Date: 2015.07.07 THE GOVERNMENT OF THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY DEPARTMENT OF HEALTH & HUMAN SERVICES

AI summary

An antenna for passing a cable to a second antenna includes shorts positioned along a circumferential perimeter of the antenna, first and second bicone sections of oppositely directed conductive cone sections energized at respective apices and opening along an antenna axis, first and second dipole sections, where the first dipole section is joined together with and extending from the first conical section to the circumferential perimeter of the antenna, and where the second dipole section is joined together with and extending from the second conical section to the circumferential perimeter of the antenna.