Adjustable Multiband Antenna Switching for Band Displacement
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Solution Overview
Problem
Existing multiband antennas in mobile terminals face challenges in adjusting resonance frequencies to cover multiple radio systems' frequency ranges due to reduced bandwidth caused by device miniaturization, making it difficult to simultaneously secure proper transmission and reception in systems like GSM1800 and GSM1900, and requiring complex structures for controlled band displacement.
Innovation Solution
An adjustable multiband antenna using a multi-pole switch and an LC circuit connected to the radiator, allowing independent displacement of two operating bands with minimal space and high efficiency, where the LC circuit also functions as an electro-static discharge protector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the distance between the radiating plane and the ground plane is reduced to decrease device thickness, then the device thickness is reduced, but the antenna bandwidth decreases making it difficult to cover multiple radio systems' frequency ranges
Solution Approach 1:
The patent applies dynamics by making the antenna's electrical length adjustable through a switchable adjusting circuit. The circuit can connect different transmission line configurations (open-ended or short-circuited) to the radiating plane, dynamically changing the antenna's resonant frequency and bandwidth to cover different radio systems (GSM850, GSM900, GSM1800, GSM1900) despite the reduced distance between radiating plane and ground plane.
2Device complexity
If a simple switch is used to adjust antenna resonance frequency, then the device complexity is reduced, but the ability to control displacement of multiple operating bands independently is lost
Solution Approach 1:
The patent segments the adjusting circuit into multiple independent adjustable elements: a first adjusting circuit with a first switch for controlling the lower operating band, and a second adjusting circuit with a second switch for controlling the upper operating band. This segmentation allows independent displacement control of each band while keeping each individual switch and circuit segment relatively simple.
Solution Approach 2:
The adjusting circuit is designed with multi-functionality to handle multiple radio systems across different frequency ranges. The same basic circuit structure (with switches, transmission lines, and reactive elements) can adjust both lower and upper operating bands to cover GSM850, GSM900, GSM1800, and GSM1900 systems, making the circuit universally applicable to various frequency requirements.
3Adaptability or versatility
If multiple separate adjusting circuits are used to control each operating band independently, then the independent band displacement control is achieved, but the device complexity and production costs increase
Solution Approach 1:
The patent merges the adjusting circuits for lower and upper operating bands into a single integrated structure. Both adjusting circuits share common components including the radiating plane, ground plane, and portions of the transmission lines. The first and second switches control different segments of the same transmission line structure, reducing overall component count and production complexity while maintaining independent control capability.
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
Achieves desired frequency band displacements for both operating bands with a simple adjusting circuit, maintaining high antenna efficiency and reducing production costs, while allowing for compact design and effective ESD protection.
Implementation Method 1
The adjusting circuit comprises an LC circuit with an input coupled to the radiating plane
Implementation Method 2
The adjusting circuit comprises a multi-pole switch, by which said radiator point can be connected to one of alternative transmission lines. When the switch is closed, the electric length of the radiator is decreased, in which case the antenna resonance frequency becomes higher
Implementation Method 3
A capacitor can be in series with the switch to set the band displacement as large as desired
Implementation Method 4
the LC circuit also functions as an electro-static discharge protector
Data Source
AI summary
An adjustable multi-band planar antenna especially applicable in mobile terminals and a radio device. The adjusting circuit (430) of the antenna is galvanically connected to a point (X) of the radiator, where the circuit can affect the places of at least two operating bands. The adjusting circuit comprises a multi-pole switch (433), by which said radiator point can be connected to one of alternative transmission lines. For example, one of two transmission lines (434, 435) is open and another shorted. A discrete capacitor (C2) can be located between the separate conductor of the transmission line and an output pole of the switch as an additive-tuning element. The adjusting circuit further comprises a LC circuit (432) between the radiator (320) and the switch. Among other things, the lengths of the transmission lines, the values of the discrete components and the distance between the antenna short-circuit point (G) and the adjusting circuit connecting point (X) are then variables from the point of view of the antenna adjusting. Such values are calculated for these variables that each of the antenna operation bands separately shifts to a desired other place when the switch state is changed. The space required for the adjusting circuit is relatively small, and a relatively high efficiency is achieved for the antenna despite of the use of a switch.