Log Periodic Conformal Antenna for Aerodynamic Gain and Bandwidth

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Solution Overview

Problem

Conformal, aerodynamic low-band open communications systems in the 0.7 GHz-2.0 GHz range face limitations in scalability of gain and beamwidth, with existing antennas having low realized gain and narrow instantaneous bandwidth, and ultra-wide band radiating elements being too thick for aerodynamic applications.

Innovation Solution

A log periodic antenna system with conformal radiating elements, incorporating a feed layer with phase shifters and filters, such as low-pass or band-pass filters, to enhance gain and bandwidth while reducing directionality, and arranging radiating elements on opposing sides or periodically around the antenna for increased omnidirectional coverage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If individual ultra-wide band radiating elements are used in 1/2-wave sampled arrays, then bandwidth is improved, but the elements become too thick for aerodynamic application

Engineering Contradiction:

Improveinstantaneous bandwidthVSAvoidelement thickness

Core Design Contradiction:

Duration of action of stationary objectVSLength of stationary object

Solution Approach 1:

The patent changes the operating parameters by using 1/4-wave sampled arrays instead of 1/2-wave arrays, which allows ultra-wideband radiating elements to achieve the required bandwidth while reducing thickness to be aerodynamically acceptable. This parameter change resolves the contradiction between bandwidth and thickness.

Inventive Principle:

Principle #35Parameter changes

2Power

If microstrip radiating elements are used in log periodic arrays, then gain is improved, but higher-order resonances limit the bandwidth of the entire array

Engineering Contradiction:

Improverealized gainVSAvoidinstantaneous bandwidth

Core Design Contradiction:

PowerVSDuration of action of stationary object

Solution Approach 1:

The patent extracts and eliminates the harmful higher-order resonances from the system by using 1/4-wave sampled spacing, which prevents the excitation of these resonances. This allows the log periodic array to maintain both high gain and wide bandwidth without the limiting effect of higher-order modes.

Inventive Principle:

Principle #2Taking out (Extraction)

3Shape

If existing conformal radiating elements are used, then aerodynamic profile is improved, but bandwidth is too narrow relative to 3:1 instantaneous bandwidth requirement

Engineering Contradiction:

Improveaerodynamic profileVSAvoidinstantaneous bandwidth

Core Design Contradiction:

ShapeVSDuration of action of stationary object

Solution Approach 1:

The patent implements a log periodic array configuration where the radiating elements are dynamically scaled in size and spacing according to the logarithmic periodic function. This dynamic arrangement allows conformal elements to maintain aerodynamic profiles while achieving 3:1 instantaneous bandwidth through the progressive scaling of element dimensions across the frequency range.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11688948B2Low-band UWB conformal antenna

Publication Date: 2023.06.27 ROCKWELL COLLINS INC

AI summary

A log periodic antenna system with conformal radiating elements includes a feed layer with phase shifters and filters associated with each radiating element. The filters may be low-pass or band-pass filters. The log periodic conformal radiating elements produce superior gain and bandwidth, and reduce directionality of the antenna at least along a radial axis of the antenna. Sets of conformal radiating elements are disposed on opposing sides of the antenna, or periodically around the surface of the antenna, to further reduce directionality.