Segmented Antenna Rod for VHF Reception in Low-Height Vehicles
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Solution Overview
Problem
Existing short rod antennas for radio reception in vehicles are inefficient in the VHF frequency range and are too long to be practical for use in low-height vehicles, posing a challenge in design and manufacturability, especially when needing to cover both radio broadcasting and mobile radio frequencies like 900 MHz and 1.8 GHz.
Innovation Solution
The antenna rod features a stretched electrically conductive coupling conductor for capacitive coupling to the antenna coil over the length of a cover, with a low-loss insulator and a parallel resonant circuit, allowing for increased reception voltage and bandwidth, and is designed with a coupling helix for a two-circuit resonance band filter, enabling operation in VHF, FM, and L-band frequencies with a shorter length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the antenna rod length is reduced for use in low-height vehicles, then the antenna becomes more practical for vehicle installation, but the receiving voltage and bandwidth in the VHF frequency range deteriorate
Solution Approach 1:
The antenna rod is segmented into functionally distinct sections: a first section with a first pitch for VHF optimization and a second section with a second pitch for higher frequency optimization. This segmentation allows each section to be optimized for its specific frequency range, enabling the short antenna to maintain good receiving characteristics in the VHF range while also supporting higher frequencies.
Solution Approach 2:
Different sections of the antenna rod are given different local qualities through varied pitch configurations. The first section has a first pitch optimized for VHF receiving voltage, while the second section has a second pitch optimized for higher frequency operation. This local differentiation allows the antenna to achieve multiple functions within a compact overall length.
2Length of moving object
If the antenna rod length is reduced for use in low-height vehicles, then the antenna becomes more practical for vehicle installation, but the bandwidth deteriorates
Solution Approach 1:
The antenna rod is segmented into functionally distinct sections: a first section with a first pitch for VHF optimization and a second section with a second pitch for higher frequency optimization. This segmentation allows each section to be optimized for its specific frequency range, enabling the short antenna to maintain good receiving characteristics in the VHF range while also supporting higher frequencies.
Solution Approach 2:
The antenna rod is designed to perform multiple functions across different frequency ranges through its differentiated pitch structure. The first section handles VHF frequency operations while the second section handles higher frequency operations, making the single antenna structure universal for multiple radio services including FM broadcasting and mobile radio communications.
3Adaptability or versatility
If a differentiated pitch is implemented to support multiple frequencies, then the antenna can operate in both VHF and higher frequency ranges, but the manufacturing complexity and cost increase
Solution Approach 1:
The antenna rod implements parameter changes by varying the pitch along its length. The pitch transitions from a first pitch in the first section to a second pitch in the second section. This parameter variation enables multi-frequency operation while the pitch can be controlled during manufacturing processes such as extrusion or forming, allowing for cost-effective production of the differentiated structure.
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
This design significantly increases reception voltage and bandwidth in the VHF frequency range while allowing operation in higher frequency bands, achieving a cost-effective and compact antenna solution suitable for multiple radio services with reduced manufacturing complexity.
Implementation Method 1
The coupling conductor 4 is routed in a covering 9 from several, but at least two turns of the coil 2 via a low-loss insulator 10 arranged between them, over the length of the covering 9 to the antenna coil 2 in a galvanically isolated manner, so that over this length there is a capacitive coupling to the antenna coil 2
Implementation Method 2
the coupling conductor 4, which consists of a stretched, electrically conductive element and is guided parallel to the rod axis 8 of the antenna rod 1... increases the reception voltage of the antenna rod 1 in the VHF frequency range
Implementation Method 3
via a low-loss insulator 10 arranged between them
Implementation Method 4
with a parallel resonant circuit 35 for measuring the impedance 33 with two low-impedance resonance points
Implementation Method 5
The radiator bandwidth of electrically short rod antennas increases approximately with the third power of the length of the antenna rod related to the free space wavelength of the operating frequency
Data Source
Figure 1a~1d
Figure 1b~1c
Figure 2
AI summary
The antenna rod (1) has a plastic rod (7) on which an antenna-spiral coil (2) is attached. An elongated electrically conductive element is guided as coupling conductor (4) for electromagnetic coupling to the antenna-spiral coil at the lower end of the plastic rod and parallel to the rod axis (8) in clamping surface of the two windings of the antenna-spiral coil. The coupling conductor is isolated from the antenna-spiral coil through a low-loss isolator so that a capacitive coupling is given to the antenna-spiral coil.