Multi-band Antenna with Planar Reflector and LC Band-stop Filter
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Solution Overview
Problem
Multi-band antennas face challenges in minimizing interference and distortion between radiating elements operating at different frequency bands, leading to undesirable radiation patterns and increased antenna size due to grating lobes and coupling issues.
Innovation Solution
The design incorporates a planar reflector with first and second pairs of dipoles arranged in a box dipole configuration, featuring printed circuit board portions with metal segments and inductor-capacitor circuits that define a filter aligned to a higher frequency range, reducing interaction between low- and high-band radiating elements through capacitive coupling and band-stop filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple radiating elements for different frequency bands are implemented in a multi-band antenna, then the antenna can operate across multiple frequency bands, but interference and distortion between radiating elements occurs leading to distorted radiation patterns
Solution Approach 1:
A planar reflector is introduced as an intermediary component between radiating elements of different frequency bands. The reflector is positioned behind the radiating elements and configured to reflect electromagnetic waves, thereby isolating the elements and preventing mutual interference and distortion of radiation patterns while maintaining multi-band operation capability
2Area of stationary object
If radiating elements for different frequency bands are placed close together, then the antenna size is reduced, but coupling issues and interference between elements increase
Solution Approach 1:
The planar reflector serves as a spatial separator and electromagnetic shield between closely spaced radiating elements. By positioning the reflector behind the elements, it creates electromagnetic isolation that reduces coupling and interference, enabling compact antenna design without sacrificing performance
Solution Approach 2:
Instead of increasing horizontal spacing between radiating elements to reduce interference, the planar reflector utilizes the vertical dimension by being positioned behind the elements. This three-dimensional arrangement allows compact horizontal footprint while maintaining electromagnetic isolation through the reflector's positioning in the vertical dimension
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 configuration effectively reduces distortion and interference between frequency bands, maintaining stable radiation patterns across multiple bands while minimizing the physical size of the antenna, allowing for efficient operation in dual- or multi-band cellular base station antennas.
Implementation Method 1
The inductor-capacitor circuits define a filter aligned to a frequency range higher than an operating frequency range of the first and second pairs of dipoles
Implementation Method 2
reducing interaction between low- and high-band radiating elements through capacitive coupling and band-stop filtering
Data Source
AI summary
A dipole antenna includes a planar reflector and a radiating element. The radiating element includes first and second pairs of dipoles on a surface of the planar reflector. The first and second pairs of dipoles respectively include arm segments arranged around a central region in a box dipole arrangement. The arm segments may be printed circuit board portions having respective metal segments and respective inductor-capacitor circuits thereon. The inductor-capacitor circuits define a filter aligned to a frequency range higher than an operating frequency range of the first and second pairs of dipoles.