Patch Antenna Spurious Resonance Suppression Using EBG

Overview of Technical Issues:

The dielectric substrate and ground plane interface allows harmful surface wave propagation that excites spurious resonant modes in the patch antenna, causing radiation pattern distortion, reduced efficiency, and unwanted frequency responses; the goal is to suppress these spurious resonances using EBG structures while maintaining the fundamental antenna performance.

Solution directions generated for this problem

Problem Direction 1 :

ImproveSurface wave attenuation coefficient
VS
ConstraintSubstrate structural complexity

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
Projected artificial magnetic mirror
Innovative Solution Refine solution

Modular pre-fabricated EBG tile assembly for surface wave suppression

Divide EBG into standardized tiles for independent fabrication and field assembly
How to solve :
  • Design standardized EBG tiles (50mm×50mm) with pre-fabricated periodic patches and vias, each tile achieving 8-10dB attenuation
  • fabricate tiles independently using standard PCB processes with ±0.05mm tolerance, then assemble 3×3 tile array beneath patch antenna to achieve cumulative >20dB attenuation
  • Implement plug-and-play electrical interconnects using spring-loaded pogo pins at tile edges (contact resistance <10mΩ) to maintain electromagnetic continuity without complex soldering
  • Use alignment registration holes (Ø2mm, ±0.02mm) at tile corners with precision jig during assembly, ensuring inter-tile gap <0.1mm to prevent bandgap degradation
Expected Effect : Attenuation >22dB within 0.5λ; fabrication complexity reduced 60% vs monolithic EBG; assembly time <15min
Risk Control :
  • inter-tile contact resistance drift
  • alignment jig positioning error accumulation
  • tile-to-tile phase discontinuity

Problem Direction 2 :

ImproveSurface wave attenuation coefficient
VS
ConstraintFabrication precision requirement

Inspiration 1 : Cross-domain reference

Application Principle: #35 Parameter changes
Cross-domain applicability Assess applicability
Detector with reduced fluorescence range noise
Innovative Solution Refine solution

Magneto-dielectric substrate with permeability-tuned surface wave suppression

Replace geometric EBG with material property control
How to solve :
  • Use magneto-dielectric composite substrate (ferrite-PTFE matrix, μr=2.5–4.0, εr=2.2–3.5) where surface wave suppression depends on permeability rather than geometric precision
  • Fabricate substrate by mixing carbonyl iron particles (15–25% volume fraction, 2–5μm diameter) into PTFE resin, hot-press at 340–360°C under 8–12 MPa for 15 minutes, achieving uniform permeability distribution
  • Control particle loading gradient through substrate thickness (top layer 18%, bottom layer 22%) to create impedance mismatch that attenuates surface waves by >20dB within 0.5λ while maintaining ±0.1mm fabrication tolerance
Expected Effect : Surface wave attenuation >22dB at 0.5λ, tolerance relaxed to ±0.1mm, efficiency >78%
Risk Control :
  • permeability uniformity variation across substrate area
  • particle agglomeration during hot-pressing
  • temperature-dependent permeability drift

Problem Direction 3 :

ImproveSpurious mode suppression bandwidth
VS
ConstraintSubstrate structural complexity

Inspiration 1 : Cross-domain reference

Application Principle: #15 Dynamics
Cross-domain applicability Assess applicability
Tunable antenna systems
Innovative Solution Refine solution

Frequency-adaptive impedance boundary layer for wideband surface wave suppression

Adaptive impedance boundary using frequency-dependent materials
How to solve :
  • Integrate frequency-selective resistive sheets (FSS-R) between substrate and ground plane—material resistance varies 50-500Ω/sq across operational bandwidth, naturally attenuating surface waves at multiple frequencies without geometric periodicity
  • Use carbon-loaded polymer composite (εr=3.5, tanδ=0.15-0.45 frequency-dependent) in 0.2mm thickness, commercially available as Laird TFlex or Cuming C-RAM materials, laminated via standard PCB bonding at 120°C, 2MPa for 30min
  • Implement graded impedance transition by stacking 2-3 FSS-R layers with different carbon loadings (5%, 10%, 15% by weight)—each layer targets different spurious frequency bands, achieving >20dB attenuation across ±15% bandwidth while maintaining single planar assembly
  • Quality control: measure sheet resistance at 3 test frequencies (f₀, 0.85f₀, 1.15f₀) with four-point probe, acceptance ±10% from nominal
  • verify layer thickness 0.2±0.02mm via micrometer
  • validate attenuation via network analyzer S-parameter measurement across full band, reject if any frequency shows <18dB suppression within 0.5λ distance
Expected Effect : Suppression bandwidth 30% vs 10% conventional EBG; structural layers 2-3 vs 5-7 multi-layer EBG; fabrication tolerance relaxed to ±0.05mm; radiation efficiency recovered to 78-82%
Risk Control :
  • frequency-dependent material parameter drift with temperature ±15°C
  • bonding interface delamination under thermal cycling
  • carbon particle distribution non-uniformity affecting impedance consistency
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