Enhanced Response Calibration

Enhanced Response calibration is a simplified calibration method when you only need S11 or S21 measurements. It is faster than full SOLT calibration but provides reduced accuracy.

What You Will Learn

• When to use Enhanced Response calibration
• S11-only calibration (OPEN or SHORT)
• S21-only calibration (THRU)
• Limitations of simplified calibration

When to Use Enhanced Response

Enhanced Response calibration is appropriate when:

• You only need S11 OR S21 (not both simultaneously)
• You want a quick calibration for field work
• You do not have a complete calibration kit
• Absolute accuracy is less critical than relative measurements

Caution

Enhanced Response provides reduced accuracy compared to full SOLT calibration. For precision measurements, always use Full Calibration.

S11 Enhanced Response (Reflection Only)

For S11 measurements, you can calibrate with just OPEN or SHORT (not both).

Using OPEN Only

1. Set your frequency range

   Go to STIMULUS and configure START and STOP frequencies.

2. Open calibration menu

   Go to CAL > CALIBRATE

3. Perform OPEN calibration

   • Remove the connector from Port 1 or connect an OPEN standard
   • Touch OPEN
   • Wait for sweep to complete

4. Complete calibration

   Touch DONE

Using SHORT Only

1. Set your frequency range

2. Open calibration menu

   Go to CAL > CALIBRATE

3. Perform SHORT calibration

   • Connect SHORT standard to Port 1
   • Touch SHORT
   • Wait for completion

4. Complete calibration

   Touch DONE

Note

With only OPEN or SHORT, the firmware calculates reflection tracking (Er) but cannot determine directivity (Ed) or source match (Es). This limits accuracy for impedances far from the calibration standard.

S21 Enhanced Response (Transmission Only)

For S21 measurements, you can calibrate with just THRU.

1. Set your frequency range

   Go to STIMULUS and configure START and STOP frequencies.

2. Connect cables in THRU configuration

   Connect your Port 1 cable directly to your Port 2 cable (or use a THRU standard).

3. Open calibration menu

   Go to CAL > CALIBRATE

4. Perform THRU calibration

   • Touch THRU
   • Wait for sweep to complete

5. Complete calibration

   Touch DONE

Enabling Enhanced Response Mode

The NanoVNA automatically detects Enhanced Response mode based on which calibration standards were performed.

You can also explicitly enable it:

1. Go to calibration menu

   Touch CAL

2. Select Enhanced Response

   Touch ENHANCED RESPONSE

   This toggles Enhanced Response mode on or off.

3. Check the status indicator

   When Enhanced Response is active, the calibration indicator may show differently than full calibration.

Understanding the Limitations

S11 Enhanced Response Limitations

Missing Standard	Impact
No LOAD	Directivity error not corrected
No SHORT (when using OPEN)	Limited accuracy for low-impedance loads
No OPEN (when using SHORT)	Limited accuracy for high-impedance loads

Practical impact:

• Works well for measuring resonant antennas near 50 ohms
• Less accurate for very low or very high impedances
• Phase accuracy is reduced

S21 Enhanced Response Limitations

Missing Standard	Impact
No ISOLN	Port crosstalk not corrected
No Port 1 calibration	Source match errors not corrected

Practical impact:

• Good for measuring insertion loss of attenuators and filters
• Less accurate for devices with poor return loss
• Isolation measurements may show floor at -40 to -50 dB

Quick Reference: Minimum Calibration Requirements

S11 Only

Minimum: OPEN only or SHORT only

Better: OPEN + SHORT

Best: OPEN + SHORT + LOAD (full S11 calibration)

Use for: Antenna SWR, return loss measurements

S21 Only

Minimum: THRU only

Better: THRU + ISOLN

Best: Full SOLT (OPEN + SHORT + LOAD + THRU)

Use for: Filter insertion loss, cable loss measurements

Both S11 and S21

Minimum: Not recommended

Required: Full SOLT calibration

Use for: Complete device characterization, accurate impedance and transmission measurements

Example: Quick Antenna Check in the Field

When you need a fast antenna check without a full calibration kit:

1. Set frequency range for your band

   Example: 144 MHz to 148 MHz for 2m band

2. Calibrate with OPEN

   Remove the antenna connector and perform OPEN calibration.

3. Connect your antenna

4. Read SWR

   The SWR reading will be approximate but useful for tuning.

5. For better accuracy

   If you have a SHORT standard (even a piece of wire soldered across an SMA connector), perform SHORT calibration as well.

Tip

In the field, even an approximate calibration is better than no calibration. You can identify the resonant frequency and relative SWR minimum without perfect accuracy.

Comparing Calibration Methods

Method	Standards Required	S11 Accuracy	S21 Accuracy	Speed
No calibration	None	Poor	Poor	Instant
OPEN only	1	Fair	N/A	Fast
SHORT only	1	Fair	N/A	Fast
THRU only	1	N/A	Fair	Fast
OPEN + SHORT	2	Good	N/A	Fast
THRU + ISOLN	2	N/A	Good	Fast
Full SOLT	4-5	Excellent	Excellent	Moderate

Switching Between Calibration Modes

1. Check current calibration status

   The status bar shows which calibration is active.

2. Recall a different calibration

   Go to CAL > menu to access saved calibrations.

3. Reset and recalibrate

   Go to CAL > RESET to clear current calibration, then perform new calibration.

Next Steps

• Full Calibration - Complete SOLT procedure
• Saving Calibration - Store calibration for reuse
• Your First S11 Measurement - Apply your calibration