Antenna Canopy Structure for Tropospheric Interference Suppression
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Solution Overview
Problem
Existing cellular networks suffer from Tropospheric duct interference due to RF signals being trapped in atmospheric ducts, causing severe interference between aggressor and victim sites, leading to call drops and degraded uplink KPIs, with current suppression methods being ineffective and reactive.
Innovation Solution
An antenna canopy structure with a mesh-type metal sheet and predefined cutouts is mounted on base station antennas to filter RF signals, reducing upper and grating lobes and preventing signal leakage into duct regions, while maintaining main lobe radiation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If high gain directional antennas are used to concentrate RF energy within a specific cell area, then coverage in the desired cell region is improved, but RF energy from side-lobes and back-lobe causes interference to distant sites
Solution Approach 1:
An antenna canopy is introduced as an intermediary structure between the antenna and the environment. The canopy includes a reflective surface that intercepts RF energy from side-lobes and back-lobe before they can propagate into the atmosphere and cause tropospheric duct interference, while allowing the main lobe to continue providing cell coverage
Solution Approach 2:
The canopy converts the harmful RF energy in side-lobes and back-lobe into a beneficial effect by reflecting it back toward the antenna or directing it away from duct regions. This transforms the interference-causing energy into a controlled component that no longer causes tropospheric duct interference
2Object-generated harmful factors
If electrical tilt is applied to the antenna to reduce interference, then interference to distant sites is reduced, but coverage of implemented cells is degraded
Solution Approach 1:
The canopy is designed to provide localized interference suppression specifically in the directions of side-lobes and back-lobe, while leaving the main lobe radiation pattern unchanged. This allows interference reduction without affecting cell coverage, as the canopy only affects specific angular regions rather than the entire radiation pattern
3Object-generated harmful factors
If side-lobes are suppressed by antenna design, then interference is reduced, but suppression is limited to 2-3 dB even with costly antenna designs
Solution Approach 1:
The interference suppression function is segmented from the antenna itself and implemented by a separate canopy structure. This allows the antenna to maintain its original radiation pattern and performance, while the canopy provides additional interference suppression capability that goes beyond what can be achieved through antenna design alone
4Object-generated harmful factors
If a canopy structure is added to reduce interference, then tropospheric duct interference is reduced, but wind load and weight on the tower increase
Solution Approach 1:
The canopy is constructed using thin, lightweight materials such as mesh or thin metal sheets that provide the necessary reflective function while minimizing weight and wind load. These thin film structures allow wind to pass through or flow over them, significantly reducing the effective wind load compared to solid canopy structures
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 antenna canopy effectively reduces Tropospheric interference, minimizing victim sites and maintaining antenna performance without additional wind load or weight, and enhancing user throughput.
Implementation Method 1
The boundary between the two layers of the air reflects signals when their angle of incidence is in the appropriate range
Implementation Method 2
The antenna beam includes the directive main lobe, back lobe and multiple side-lobes
Implementation Method 3
The ducting phenomenon causes the RF signal radiated from the antenna to get trapped in this duct, undergo multiple reflections with minimal attenuation
Data Source
AI summary
The present disclosure provides for a system facilitating reduction of network self-interference. The system is equipped with an innovative antenna canopy structure which can be mounted on the top of a base station antenna to suppress an RF signal level propagating through upper side-lobes of the base station antenna above the horizon. The antenna canopy structure further ensures that there is no effect of wind load when mounted in the antenna top and also to reduce its weight.