LC Matching Tool

The L/C Match function calculates component values for L-network matching circuits. Given the measured impedance at the marker position, it computes up to 4 matching solutions.

Enable L/C Match Mode

1. Tap the screen to open the menu
2. Navigate to DISPLAY > MEASURE
3. Tap L/C MATCH
4. Position a marker at the frequency where you want to match

Note

The L/C Match function requires an active marker. Enable at least one marker before using this feature.

Understanding the Display

When L/C Match is active, the screen shows:

L/C match for source Z0 = 50 ohms
Src shunt    Series      Load shunt
  ---        10.5 nH       ---
  47 pF      10.5 nH       ---
  ---        8.2 nH       68 pF
  47 pF      8.2 nH       68 pF

Each row is a valid matching solution:

• Src shunt: Component in parallel with the source (50 ohm side)
• Series: Component in series between source and load
• Load shunt: Component in parallel with the load

Matching Solutions

The L-network calculator provides different solutions depending on the load impedance:

High Impedance Loads (R > Z0)

Two solutions using shunt capacitor/inductor at the load:

Source --- Series L/C --- Load
                          |
                       Shunt L/C

Low Impedance Loads (R < Z0)

Two solutions using shunt capacitor/inductor at the source:

Source --- Series L/C --- Load
   |
Shunt L/C

Near 50 Ohms

If the load is close to 50 ohms (SWR < 1.1), only a series reactance is needed to cancel the reactive component.

Reading Component Values

The display shows:

• Positive values = Inductors (H, nH, uH)
• Negative values = Capacitors (F, pF, nF)

Example readings:

• 10.5 nH = 10.5 nanohenry inductor
• 47 pF = 47 picofarad capacitor
• --- = No component needed

Shell Commands

# Enable L/C match mode
measure lc

# Disable measurement modes
measure none

Practical Example

Matching a 25 + j30 ohm antenna to 50 ohms:

1. Connect antenna to CH0
2. Set sweep to cover the operating frequency
3. Enable a marker at the desired frequency
4. Go to DISPLAY > MEASURE > L/C MATCH
5. Read the matching solutions
6. Choose the solution that uses available component values

Choosing a Solution

When multiple solutions are presented, consider:

Factor	Consideration
Component values	Choose values you have available
Bandwidth	Shunt at load gives wider bandwidth for high-Z loads
DC path	Series inductor allows DC pass-through
Harmonic suppression	Choose topology that attenuates harmonics
Physical size	Higher inductance = larger inductor

Tip

For antenna matching, a series inductor with shunt capacitor at the load often gives the widest bandwidth.

Limitations

• Calculations assume ideal components (no losses, no parasitics)
• Valid only at the exact marker frequency
• Component values may need adjustment for real-world implementation
• Does not account for component Q factor

Building the Match

Once you have the calculated values:

1. Note the required component values
2. Select standard component values close to calculated
3. Build the L-network on a test board
4. Measure the matched impedance with NanoVNA
5. Adjust component values as needed for best match

Caution

At frequencies above 100 MHz, component parasitics become significant. The actual matching network may need different values than calculated.

Disable L/C Match

1. Go to DISPLAY > MEASURE
2. Tap NONE to disable the measurement overlay