Bendable Monopole Antenna Reactance Compensation Circuit
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Solution Overview
Problem
Existing short-rod monopole antennas for mobile use, such as in vehicles, face limitations in bandwidth due to fixed radiator lengths, requiring mechanical tuning which is costly and impractical for frequent channel changes, and existing solutions that modify antenna structures for broadband adaptation are inefficient.
Innovation Solution
A coiled short-rod monopole antenna with a compensation circuit formed by a series resonant circuit and a parallel resonant circuit, including a capacitor and inductor, which compensates for the radiator's reactance across the frequency band, allowing for increased bandwidth without mechanical adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the radiator length is fixed to reduce mechanical complexity, then device complexity is reduced, but bandwidth is limited
Solution Approach 1:
The patent changes the electrical parameters of the antenna system by introducing a compensation circuit with variable capacitance and inductance values. This circuit compensates for the reactive component of the antenna impedance across a wide frequency range, enabling broadband operation without mechanical tuning of the radiator length.
Solution Approach 2:
The patent replaces mechanical tuning mechanisms (such as telescopic radiators or sliding contacts) with an electrical compensation circuit. This substitution eliminates mechanical complexity while achieving the same goal of bandwidth adaptation through electrical parameter adjustment.
2Adaptability or versatility
If mechanical tuning devices are added to increase bandwidth, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent eliminates mechanical tuning devices by implementing an all-electrical compensation circuit. The circuit uses variable capacitors and inductors to adjust the impedance matching electronically, replacing what would traditionally require mechanical movement or adjustment.
Solution Approach 2:
Instead of changing the physical dimensions of the radiator through mechanical means, the patent changes the electrical parameters (capacitance and inductance) of the compensation circuit to achieve impedance matching across different frequencies, thereby increasing bandwidth without mechanical complexity.
3Adaptability or versatility
If the radiator length is extended to increase bandwidth, then adaptability is improved, but the antenna height exceeds vehicle limitations
Solution Approach 1:
The patent uses parameter changes in the compensation circuit to achieve broadband performance without increasing the physical length of the radiator. By adjusting the capacitance and inductance values in the compensation circuit, the antenna maintains impedance matching across a wide frequency range while keeping the radiator length short and suitable for vehicle mounting.
Solution Approach 2:
The compensation circuit acts as an intermediary between the short radiator and the transmission line. It transforms the impedance characteristics of the short radiator to match the required bandwidth requirements, effectively decoupling the relationship between radiator length and bandwidth.
4Adaptability or versatility
If tuning devices are added to handle multiple channels, then adaptability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces complex mechanical tuning devices with a simpler electrical compensation circuit using standard capacitors and inductors. This substitution reduces manufacturing complexity and cost while maintaining the ability to cover multiple CB channels through electrical adjustment.
Solution Approach 2:
The patent achieves multi-channel coverage by allowing parameter changes in the compensation circuit (capacitance and inductance values) rather than requiring physical reconfiguration. This electronic adjustability simplifies manufacturing while maintaining adaptability across 40 or 80 CB channels.
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 solution provides maximum bandwidth with maximum efficiency and cost-effectiveness by canceling out reactances, resulting in improved antenna performance and simplified assembly, with a gain of up to 4 dB in bandwidth compared to antennas without the compensation circuit.
Implementation Method 1
a parallel resonant circuit, in particular consisting of a capacitor CK and an inductor LK, which is connected to a base of the radiator and which compensates for a reactance of the radiator below and above the resonant frequency
Implementation Method 2
the reactance of the radiator below and above the resonant frequency is compensated for by the parallel resonant circuit
Data Source
Figure 1
Figure 2a~3
Figure 4~5
AI summary
The invention relates to a bendable monopole antenna for use in mobile environments, consisting of a radiating element, an antenna base, an antenna housing accommodating electric and/or electronic components, and an antenna output on the antenna housing or antenna base. According to the invention, a compensation circuit is connected to the lower end of the rod. Electrically, the rod is a series circuit consisting of a series resonant circuit and a resistor, the interface circuit being formed as a parallel resonant circuit consisting of a capacitor and an inductor.