Nested Helix Antenna Horizon Nulling
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Solution Overview
Problem
GPS timing antennas are susceptible to unintentional and intentional interference, such as out-of-band and multipath signals, and existing solutions like large antenna arrays and horizon ring nulling antennas are costly and limited in their ability to reject interference across all polarizations.
Innovation Solution
The development of multi-band helix antennas with nested helices, where the outer helix is configured to minimize disruption to the inner helix's radiation pattern using trap circuits, enabling a compact, low-cost antenna with a deep null in the gain pattern for horizon-based interference rejection across all polarizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large antenna arrays are used to reject horizon-based interference, then interference rejection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs nested helical structures where an inner helix and outer helix are concentrically arranged. The inner helix operates at a higher frequency band while the outer helix operates at a lower frequency band. This nesting configuration enables the antenna to achieve horizon nulling capability without requiring large antenna arrays, thereby reducing device complexity while maintaining interference rejection performance.
2Object-affected harmful factors
If horizon ring nulling antennas are used to achieve deep null at horizon, then interference rejection is improved, but cost increases due to active electronics
Solution Approach 1:
The patent extracts and eliminates the requirement for active electronics from the antenna design. Instead of using active circuitry to achieve horizon nulling, the invention employs passive reactive elements (inductors and capacitors) integrated into the helical structure. This extraction of active components significantly reduces manufacturing cost while maintaining the deep null capability at the horizon for interference rejection.
Solution Approach 2:
The patent replaces expensive active electronic components with inexpensive passive reactive elements. The use of simple inductors and capacitors integrated into the helix structure provides a low-cost alternative to active electronics, achieving the same horizon nulling function at a fraction of the cost.
3Adaptability or versatility
If nested helices are used for multi-band operation, then frequency band coverage is improved, but radiation pattern distortion increases
Solution Approach 1:
The patent applies local quality by making the outer helix selectively non-radiating at the inner helix's operating frequency. Reactive elements are strategically placed on the outer helix to create high impedance at the inner helix frequency, preventing the outer helix from radiating or absorbing energy at that frequency. This local modification allows the outer helix to be present for structural support and lower band operation without disturbing the inner helix's radiation pattern.
4Strength
If outer helix is present for structural support, then mechanical strength is improved, but inner helix radiation is shielded
Solution Approach 1:
The patent introduces reactive elements (inductors and capacitors) as intermediaries between the outer helix structure and the electromagnetic field. These reactive elements create a high impedance condition on the outer helix at the inner helix's operating frequency, effectively decoupling the structural support function from the radiation function. This allows the outer helix to provide mechanical strength without shielding or disturbing the inner helix's radiation.
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 multi-band helix antennas provide effective interference rejection across all polarizations, maintaining sufficient beamwidth and horizon nulling capabilities, thus enhancing the reliability of GPS timing systems while reducing costs.
Implementation Method 1
The radiating arms of the outer helix can include trap circuits configured for high impedance within or near the operating frequency of the inner helix
Implementation Method 2
GPS satellites transmit right-hand circularly polarized (RHCP) signals, and thus, GPS antennas must be right-hand circularly polarized
Data Source
AI summary
A multi-band helix antenna including one or more first arms extending helically about an axis at a first distance from the axis; and one or more second arms extending helically about the axis at a second distance from the axis that is greater than the first distance, wherein each of the one or more second arms comprises at least one trap circuit configured to have a first impedance at a resonant frequency of the one or more first arms and a second impedance at a resonant frequency of the one or more second arms, and the first impedance is greater than the second impedance.