The Beatty Standard and its Use

What is the Beatty Standard? as drawn from Reference [1]

• A series resonator between two lines of characteristic impedance Z₀.
  

  

• Z₀ length of line is 0.25 inches. Z_B length of line is 1 inch.

How it performs:

• The resonator will have a periodic response because of transmission line effects

• S₁₁ maximums (and S₂₁ minimums) will also be λ/2 apart

• S₁₁ minimum to maximum (and S₂₁ maximum to minimum) will be λ/4 apart

How the Beatty Standard Performs: Lossless

How the Beatty Standard Performs, TDR

What about Changing ε_r?

This plot shows dielectric constant sweep from 3 to 4. Changing ε_r moves the distance between maxima and minima.

Dielectric Constant, continued: Zoom in, the better to see Changing ε_r

Electrical length is changing with the dielectric constant.

Dielectric Constant, continued. Now Look at TDR to see effects of Changing ε_r

What about Metal Conductivity?

Look at DC, or a low as you can.

What does this tell us about metal conductivity? There is a change in plot shape due to loss.

• Look at DC to eliminate skin effect and surface roughness effects
• Network Analyzer is not be best tool to measure this low in frequency
• Will likely need to use Impedance Analyzer or precision Ohm-meter.
• Results of DC resistance of structure show below vs. metal conductivity

What about Loss Tangent?

The plots shows a change in shape due to substrate loss.

• We know metal conductivity from DC value, so change tan to get loss to match. Sweep from 0.001 to 0.01.
• Less change at “low frequency” and more “high-frequency” loss with tand

Now Look at TDR for Loss Tangent

This shows a change in shape due to substrate loss, with little change in TDR.

What about Surface Roughness?

This plot shows a change in shape due to roughness.

• Similar loss as loss tangent at high-frequency.
• More loss at low frequency. Match low frequency first with surface roughness.

Now Look at TDR for Surface Roughness

The plot shows change in shape due to roughness.

• More change in impedance compared to changing loss tangent.
• May be important to separate roughness from substrate loss.

Observations so Far

• Change ε_r to match spacing between maxima and minima.
• Look at very low frequency (ideally DC) to match conductivity
• Look at “low frequency” to match Surface Roughness
• Look at “high frequency” loss to match Loss Tangent after Surface Roughness is matched.
  • Look at TDR plot to help separate loss if not obvious from Frequency Domain data

Not Looking at:

• Changing line and substrate dimensions
  • Restricting variables to tune for loss
  • Need to verify all the thickness, widths, and any etch with cross-section
• Phase Information and Group Delay
  • To verify propagation time if needed for fine tuning

What Have We Haven’t Looked At

• Changing line and substrate dimensions
  • Restricting variables to tune for loss
  • Need to verify all the thickness, widths, and any etch with cross-section
• Phase Information and Group Delay
  • To verify propagation time

Next

De-embedding of the Design Under Test from Test Fixture