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2 years ago in Antenna Materials , Electrical Engineering By Hema
I’m finalizing the design of a Barium Titanate (BaTiO‑) Dielectric Resonator Antenna for 2.5 GHz. What specific, measurable material properties should I verify with my supplier to ensure simulated performance?
  My simulations assume ε?=90 and tan δ=0.001. I'm ready to order the ceramic puck, but I know BaTiO? properties vary with doping, sintering process, and frequency. What tolerances on ε? and tan δ are typical for commercial microwave-grade BaTiO?? Should I also specify the temperature coefficient of ε? (TCε) and request data at 2.5 GHz, not just 1 MHz? Are there other hidden factors like porosity or grain size that significantly affect the effective permittivity and loss at this frequency?Â
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By Atilia Answered 1 year ago
Do not rely on generic values. You must request a material datasheet with microwave-frequency data (specifically 2.5 GHz) for the exact batch. Key specs to lock down: 1) ε?: Specify a tight tolerance, e.g., 90 ± 2. 2) tan δ: Specify a maximum, e.g., ≤ 0.0015 @ 2.5 GHz. 3) Temperature Coefficient (TCε): Request the value in ppm/°C over your operational range; for BaTiO?, it can be high (~1000 ppm/°C), which may be unacceptable for outdoor use. 4) Bulk Density: Should be >95% of theoretical to minimize porosity effects. Also, ask for the quality factor (Q = 1/tan δ) at your frequency. Reputable suppliers (like Trans-Tech or TCI) provide this. Finally, order a small extra piece to characterize yourself using a resonant cavity method to validate the specs before machining the final puck. The cost of a mistaken ε? is a miss in frequency.
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