Microstrip Multi-Band Composite Antenna Design
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Solution Overview
Problem
Designing a single antenna structure capable of operating across multiple frequency bands, particularly low and high frequencies, is challenging due to the inverse proportionality of antenna dimensions with frequency, leading to cost and real estate issues in wireless communication systems.
Innovation Solution
A composite microstrip dipole antenna structure with a shorted antenna in the near field, separated by dielectric substrates of varying thickness and permittivity, allowing for multiple frequency bands to be received with increased gain, particularly at low frequencies, by utilizing a matching circuit and an electrically floating split ring resonator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single antenna is used for multiple communication protocols, then cost and real estate are reduced, but antenna performance deteriorates across different frequency bands
Solution Approach 1:
The antenna is divided into multiple arms (first arm, second arm, third arm, fourth arm) with different lengths, where each arm is responsible for different frequency bands. This segmentation allows each arm to be optimized for specific frequency ranges while collectively covering multiple bands, resolving the contradiction between multi-band adaptability and performance reliability.
Solution Approach 2:
Different arms of the antenna are assigned different lengths and positions to optimize performance for specific frequency bands. The first and second arms are longer for lower frequencies, while the third and fourth arms are shorter for higher frequencies. This local optimization ensures that each part of the antenna structure contributes to performance in its designated frequency range.
2Volume of moving object
If antenna dimensions are reduced for higher frequencies, then antenna size decreases, but low-frequency reception capability is lost
Solution Approach 1:
The antenna transitions from a conventional planar structure to a three-dimensional configuration with arms extending in multiple spatial dimensions. The arms are positioned at different heights and angles, allowing the antenna to achieve multiple wavelengths equivalent electrical length within a compact physical footprint. This dimensional transformation enables both size reduction and broad frequency coverage.
Solution Approach 2:
The antenna structure employs a nested configuration where shorter arms are positioned within the spatial envelope created by longer arms. The third and fourth arms (shorter for high frequencies) are nested within the broader structure formed by the first and second arms (longer for low frequencies), allowing multiple frequency capabilities within a compact overall size.
3Adaptability or versatility
If multiple antennas are used for different frequency bands, then frequency coverage improves, but device complexity and real estate increase
Solution Approach 1:
Multiple antenna functions are merged into a single integrated structure. The first through fourth arms form one continuous antenna assembly that provides coverage for multiple frequency bands simultaneously. This merging eliminates the need for separate antennas for different protocols, reducing both structural complexity and real estate requirements while maintaining broad frequency coverage.
Solution Approach 2:
The antenna structure is designed as a universal multi-functional system where the same physical structure serves multiple communication protocols across different frequency bands. The varied arm lengths and configurations enable the single antenna to function effectively for both lower frequency bands (requiring longer elements) and higher frequency bands (requiring shorter elements), eliminating the need for protocol-specific antennas.
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 composite antenna achieves efficient operation across various frequency bands with improved gain and reduced size, enabling the reception of signals in multiple communication protocols, including low-frequency bands like TV and high-frequency bands like DVB and UMTS, while minimizing physical dimensions.
Implementation Method 1
separated by dielectric substrates of varying thickness and permittivity
Implementation Method 2
controlling electromagnetic field distribution to enable multi-band operation
Implementation Method 3
A composite microstrip dipole antenna structure with a shorted antenna in the near field
Implementation Method 4
shorted antenna in the near field
Implementation Method 5
utilizing a matching circuit and an electrically floating split ring resonator
Data Source
AI summary
The multi-band antenna structure includes a first antenna having a band width about a middle frequency and a second antenna spaced and electrically isolated from the antenna. Ends of the second antenna are shorted to each other and the antenna floats electrically. The first and second antennas are planar and superimposed in parallel planes. At least two layers of dielectric material of a thickness is between the two antennas. A third layer of dielectric material of a third thickness is between the two antennas.