Multi-mode 3-D Traveling-Wave Antenna for Ultra-Wideband Miniaturization
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Solution Overview
Problem
Conventional omnidirectional antennas face challenges in achieving wider bandwidth, lower profile, and smaller size while adhering to the Chu limit, particularly at lower frequencies, which restricts their applicability in modern wireless applications.
Innovation Solution
The development of multi-mode 3-D traveling-wave antennas that incorporate 2-D surface-mode and 1-D normal-mode structures, along with frequency-selective couplers and dual-band feed networks, allows for broader bandwidth and reduced size, weight, and cost, by effectively utilizing the platform as part of the antenna radiator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional omnidirectional antennas are designed to satisfy the Chu limit for good efficiency and large bandwidth, then at least one dimension must be about λL/4 or larger, but this results in large antenna size particularly at lower frequencies
Solution Approach 1:
The patent transitions from conventional 1-D vertical dipole antennas to 2-D planar inverted-F antennas and further to 3-D folded configurations. This dimensional expansion allows the antenna to achieve omnidirectional radiation patterns while maintaining a compact footprint by utilizing surface area rather than height, effectively circumventing the Chu limit constraints on linear dimensions.
Solution Approach 2:
The patent employs folded antenna structures where the radiating elements are nested within a compact planar footprint. The 3-D folded configuration nests multiple radiating segments within a small area, allowing the effective electrical length to be extended without increasing the overall physical dimensions, thus achieving λL/4 electrical length in a compact form factor.
2Shape
If antenna height is reduced to achieve low profile, then bandwidth and efficiency are compromised according to the Chu limit
Solution Approach 1:
The patent compensates for reduced height by expanding the antenna structure in the planar dimensions. The 2-D planar inverted-F configuration and 3-D folded structures utilize increased surface area to maintain the electrical length and radiation efficiency that would otherwise require greater height, thereby achieving low profile without sacrificing bandwidth.
Solution Approach 2:
The patent employs composite structural configurations combining multiple radiating elements, grounding structures, and dielectric substrates in integrated 2-D and 3-D arrangements. These composite structures create distributed capacitance and inductance that extend the electrical length without increasing physical height, maintaining bandwidth performance in a low-profile configuration.
3Volume of moving object
If antenna size is reduced to meet miniaturization goals, then radiation efficiency and bandwidth performance deteriorate
Solution Approach 1:
The patent nests multiple radiating segments and folding structures within a compact volume. The 3-D folded configuration allows the antenna to achieve extended electrical length by nesting radiating paths within a small footprint, maintaining radiation efficiency and bandwidth while minimizing the overall antenna volume.
Solution Approach 2:
The patent transitions to 3-D folded structures that utilize vertical stacking and planar folding to extend the electrical length within a compact volume. This multi-dimensional arrangement allows the antenna to achieve the required electrical dimensions for broadband performance without increasing the overall volume, effectively decoupling electrical size from physical volume.
4Stability of the object's composition
If conventional dipole antennas are used for omnidirectional coverage, then uniform radiation intensity is achieved but the antenna cannot be miniaturized below Chu limit constraints
Solution Approach 1:
The patent maintains omnidirectional radiation uniformity by designing 2-D planar and 3-D folded structures with rotational symmetry about the vertical axis. These symmetric configurations ensure uniform current distribution and radiation patterns in all azimuth directions, achieving the same omnidirectional performance as conventional dipoles while enabling miniaturization through compact planar and folded geometries.
Data Source
AI summary
A class of ultra-wideband miniaturized traveling-wave (TW) antennas comprising a conducting ground surface at the base, a plurality of TW structures having at least one ultra-wideband low-profile two-dimensional (2-D) surface-mode TW structure, a frequency-selective coupler placed between adjacent TW structures, and a feed network. In one embodiment, a 2-D surface-mode TW structure is positioned above the conducting ground surface, a normal-mode TW structure placed on top with an external frequency-selective coupler placed in between; continuous octaval bandwidth of 14:1 and size reduction by a factor of 3 to 5 are achievable. In other embodiments using at least two 2-D TW structures and a dual-band feed network, a continuous bandwidth over 100:1, and up to 140:1 or more, is reachable. In yet another embodiment, ultra-wideband multi-band performance over an octaval operating bandwidth up to 2000:1 or more is feasible.