Segmented Low-Band Antenna Elements to Suppress High-Band Scattering
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Solution Overview
Problem
Undesirable interactions occur between radiating elements of different frequency bands in multiband antennas, causing scattering of high band signals, perturbations in radiation patterns, variation in azimuth beam width, and beam squint due to resonance of low band elements in the high band frequency range.
Innovation Solution
The use of low band radiating elements with conductive segments coupled by inductive elements, configured to appear as high impedance at high band frequencies and low impedance at low band frequencies, and parasitic elements with similar configurations to minimize interference and shape beam patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If low band radiating elements are used in multiband antennas, then low band radiation coverage is improved, but high band signals experience scattering and radiation pattern distortion due to resonance of low band elements at high band frequencies
Solution Approach 1:
The low band radiating element is divided into multiple conductive segments that are electrically isolated from each other at high band frequencies. Each segment is shorter than one-half wavelength at the high band frequency, preventing resonance. The segments are connected through inductive elements that provide electrical continuity at low band frequencies while maintaining isolation at high band frequencies, thus eliminating high band signal scattering while preserving low band radiation coverage.
Solution Approach 2:
Inductive elements are introduced as intermediary components between the conductive segments of the low band radiating element. These inductive elements have impedance characteristics that appear as high impedance at high band frequencies (blocking high band currents) and as lower impedance at low band frequencies (allowing low band currents to pass). This intermediary structure enables the low band element to be 'electrically invisible' at high band frequencies while maintaining functionality at low band frequencies.
2Object-affected harmful factors
If low band dipole arms are made electrically invisible at high band frequencies by using conductive segments shorter than one-half wavelength, then high band signal scattering is reduced, but the structural complexity of the low band element increases due to multiple segments and inductive elements
Solution Approach 1:
Multiple conductive segments and inductive elements are merged into an integrated low band radiating element structure. The segments and inductive elements are combined to form a unified component that maintains the overall dipole shape while incorporating the segmentation and inductive coupling features. This merging approach reduces the perceived structural complexity compared to assembling separate components, while still achieving the electrical isolation at high band frequencies.
3Object-affected harmful factors
If inductive elements are used to couple conductive segments, then high band currents are attenuated while low band currents pass through, but the impedance matching and current distribution become more difficult to control
Solution Approach 1:
The impedance characteristics of the inductive elements are specifically designed to change with frequency. At high band frequencies, the inductive elements present high impedance to block high band currents. At low band frequencies, the impedance is lower to allow current flow. This parameter change with frequency automatically controls current distribution without requiring complex external impedance matching networks, simplifying the overall design while achieving the desired current attenuation at high bands.
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
Reduces high band signal scattering and distortion by making low band elements 'electrically invisible' at high band frequencies, while maintaining control over low band beam characteristics.
Implementation Method 1
The inductive elements are selected to appear as high impedance elements at the high band operational frequency and as lower impedance elements at the low band operational frequency
Data Source
AI summary
A multiband antenna, having a reflector, and a first array of first radiating elements having a first operational frequency band, the first radiating elements being a plurality of dipole arms, each dipole arm including a plurality of conductive segments coupled in series by a plurality of inductive elements; and a second array of second radiating elements having a second operational frequency band, wherein the plurality of conductive segments each have a length less than one-half wavelength at the second operational frequency band.