Attenuator

Circuit Setup

Two-port measurement with 10 dB attenuator.

using CircuitSim

# Create circuit
circ = Circuit()

# AC power sources (S-parameter ports)
port1 = ACPowerSource("P1", port_num=1, impedance=50.0)
port2 = ACPowerSource("P2", port_num=2, impedance=50.0)

# 10 dB attenuator
att = Attenuator("ATT1", attenuation=10)

# Ground
gnd = Ground("GND")

# Add components
add_component!(circ, port1)
add_component!(circ, att)
add_component!(circ, port2)
add_component!(circ, gnd)

# Connections
@connect circ port1.nplus att.n1
@connect circ att.n2 port2.nplus
@connect circ port1.nminus gnd
@connect circ port2.nminus gnd

S-Parameter Simulation

Measure S-parameters at 5 GHz (qucsator requires at least 2 points).

# S-parameter analysis: 5 GHz with minimal span (2 points required by simulator)
analysis = SParameterAnalysis(start=5e9, stop=5.001e9, points=2, z0=50.0)

# Run simulation - returns typed SParameterResult directly
sp_result = simulate_qucsator(circ, analysis)

# Get S-parameters at first frequency point
s11 = sp_result.s_matrix[(1,1)][1]
s21 = sp_result.s_matrix[(2,1)][1]
s12 = sp_result.s_matrix[(1,2)][1]
s22 = sp_result.s_matrix[(2,2)][1]

s11_dB = 20 * log10(abs(s11))
s21_dB = 20 * log10(abs(s21))
s12_dB = 20 * log10(abs(s12))
s22_dB = 20 * log10(abs(s22))

println("S11 (input reflection) = $(s11_dB) dB")
println("S21 (forward transmission) = $(s21_dB) dB")
println("S12 (reverse transmission) = $(s12_dB) dB")
println("S22 (output reflection) = $(s22_dB) dB")

S11 (input reflection) = -Inf dB
S21 (forward transmission) = -10.0 dB
S12 (reverse transmission) = -10.0 dB
S22 (output reflection) = -Inf dB