Capacitor model tests

west_ic_antenna/antenna.py

@@ -246,8 +246,12 @@ def capa(
 
 
         """
-        z0_bridge = z0_bridge or self.bridge.z0[:, 1]
-        z0_antenna = z0_antenna or self.antenna.z0[:, 0]
+        # Port Characterics impedances
+        # NB: Taking real parts, as the small imaginary parts comes from 
+        # lossy boundary conditions in HFSS and are supposed not physical.
+        z0_bridge = z0_bridge or self.bridge.z0[:, 1].real
+        z0_antenna = z0_antenna or self.antenna.z0[:, 0].real
+
         # dummy transmission line to create lumped components
         # the 50 Ohm characteristic impedance is artifical. However, the R,L,R1,L1,C1 values
         # have been fitted to full-wave solutions using this 50 ohm value, so it should not be modified
@@ -271,7 +275,8 @@ def capa(
         # ANSYS Designer seems not doing it and leaves to 50 ohm
         # renormalizing the z0 will lead to decrease the matched capacitances by ~10pF @55MHz
         # In reality, values are closer to 50 pF at 55 MHz
-        # capa.z0 = [z0_bridge, z0_antenna]
+        capa.renormalize(z_new=np.array([z0_bridge, z0_antenna]).T)
+
         return capa
 
     def _antenna_circuit(self, Cs: NumberLike) -> 'Circuit':

west_ic_antenna/test/test_antenna.py

@@ -1,7 +1,9 @@
 # -*- coding: utf-8 -*-
+import os
 import pytest
 import skrf as rf
-import os
+import numpy as np
+
 
 from west_ic_antenna.antenna import (
     WestIcrhAntenna,
@@ -14,33 +16,161 @@
 
 # Useful definitions
 TEST_DIR = os.path.dirname(os.path.abspath(__file__))
-DATA_DIR = os.path.join(TEST_DIR, '../data')
+DATA_DIR = os.path.join(TEST_DIR, "../data")
+
 
 @pytest.fixture
 def antenna_default_arg():
     return WestIcrhAntenna()
 
+
 # Constructor Tests
 def test_constructor_default(antenna_default_arg):
     """Test creation of Antenna instance"""
     assert isinstance(antenna_default_arg, WestIcrhAntenna)
-
+
+
 def test_setup_constructor_frequency():
-    freq = rf.Frequency(30, 60, npoints=10, unit='MHz')
+    freq = rf.Frequency(30, 60, npoints=10, unit="MHz")
     _ant = WestIcrhAntenna(frequency=freq)
     assert isinstance(_ant, WestIcrhAntenna)
-
+
+
 def test_setup_constructor_capa():
     Cs = [20, 30, 40, 50]
-    _ant = WestIcrhAntenna(Cs=Cs)        
+    _ant = WestIcrhAntenna(Cs=Cs)
     assert isinstance(_ant, WestIcrhAntenna)
-
+
+
 def test_setup_constructor_frontface_filename():
-    _ant = WestIcrhAntenna(front_face=DEFAULT_FRONT_FACE)        
-    assert isinstance(_ant, WestIcrhAntenna)        
+    _ant = WestIcrhAntenna(front_face=DEFAULT_FRONT_FACE)
+    assert isinstance(_ant, WestIcrhAntenna)
+
 
 def test_setup_constructor_frontface_network():
     ntw = rf.Network(DEFAULT_FRONT_FACE)
-    _ant = WestIcrhAntenna(front_face=ntw)        
-    assert isinstance(_ant, WestIcrhAntenna)     
+    _ant = WestIcrhAntenna(front_face=ntw)
+    assert isinstance(_ant, WestIcrhAntenna)
+
+
+# Test capacitor model
+"""
+Equivalent lumped Network model of a WEST ICRH antenna capacitor.
+
+The electrical circuit of an equivalent lumped model is:
+
+    port1 (bridge side)                        port2 (antenna side)
+
+        o-- R1 -- L1 --- R -- L -- C --- L1 -- R1 --o
+                      |               |
+                      C1             C1
+                      |               |
+                      gnd            gnd
+"""
+
+
+def test_capa_model_50ohm_ports(antenna_default_arg):
+    """
+    Benchmark capacitor model with ANSYS Circuit model.
+
+    Default values and 50 Ohm port impedance in ANSYS.
+    """
+    ant = antenna_default_arg
+    cap = ant.capa(
+        C=50,
+        z0_bridge=50,
+        z0_antenna=50,
+    )
+
+    # Does it returns a Network?
+    assert isinstance(cap, rf.Network)
+
+    # ANSYS Equivalent circuit with 50 Ohm ports
+    ANSYS_model = (
+        "ANSYS_benchmarks/WEST_capacitor_equivalent_circuit_50ohm_ports.s2p"
+    )
+    cap_ANSYS = rf.Network(os.path.join(TEST_DIR, ANSYS_model))
+
+    assert cap == cap_ANSYS
+
+
+def test_capa_model_bridge_antenna_ports(antenna_default_arg):
+    """
+    Benchmark capacitor model with ANSYS Circuit model.
+
+    Specifiyng bridge and antenna ports'Z0 in ANSYS (real values).
+    """
+    ant = antenna_default_arg
+    cap = ant.capa(C=50)
+
+    # ANSYS Equivalent circuit with complex bridge and antenna ports' Z0
+    ANSYS_model = "ANSYS_benchmarks/WEST_capacitor_equivalent_circuit_bridge_antenna_ports.s2p"
+    cap_ANSYS = rf.Network(os.path.join(TEST_DIR, ANSYS_model))
+
+    assert cap == cap_ANSYS
+
+
+def test_capa_model_bridge_antenna_ports_renorm50ohm(antenna_default_arg):
+    """
+    Benchmark capacitor model with ANSYS Circuit model.
+
+    Specifiyng bridge and antenna ports'Z0 in ANSYS (real values),
+    but renormalizing ANSYS results to 50 ohm during export of Touchstone.
+    """
+    ant = antenna_default_arg
+    cap_50 = ant.capa(C=50, z0_bridge=50, z0_antenna=50)
+
+    ANSYS_model_50 = "ANSYS_benchmarks/WEST_capacitor_equivalent_circuit_bridge_antenna_ports_renorm50ohm.s2p"
+    cap_ANSYS_50 = rf.Network(os.path.join(TEST_DIR, ANSYS_model_50))
+
+    assert cap_50 == cap_ANSYS_50
+
+
+def test_capa_model_connection(antenna_default_arg):
+    """
+    Benchmark dummy circuit model of a antenna-capa-bridge vs ANSYS Circuit.
+    
+    In ANSYS, a single capacitor electrical circuit is connected to one bridge
+    output and to an antenne front face input (using HFSS model).
+    Bridge input is connected to input port and all other ports are shorted.
+    
+    Benchmark is performed when the Touchtone file is exported without and with
+    50 Ohm renormalization.
+
+    """
+    # NB: importing S-matrix in ANSYS Circuit as a N-port component 
+    # requires the user to know in advance the port char impedance
+    # ant = antenna_default_arg
+    ant = antenna_default_arg
+    cap = ant.capa(C=50)
+
+    # Creating the dummy circuit using scikit-rf
+    cap.name = 'capa'
+    port = rf.Circuit.Port(frequency=ant.frequency, name='port1', z0=ant.bridge.z0[:,0].real)
+    gnd = rf.Circuit.Ground(frequency=ant.frequency, name="gnd")
+    cnx = [
+        [(ant.bridge, 0), (port, 0)],
+        [(ant.bridge, 1), (cap, 0)],
+        [(cap, 1), (ant.antenna, 0)],
+        # grounding all other ports
+        [(gnd, 0), (ant.bridge, 2), (ant.antenna, 1), (ant.antenna, 2), (ant.antenna, 3)]
+    ]
+    cir = rf.Circuit(cnx)
+    ntw = cir.network
+
+    # ANSYS Model Export without renormalization
+    ANSYS_model = "ANSYS_benchmarks/WEST_capacitor_test_connection.s1p"
+    ANSYS_connection_test = rf.Network(os.path.join(TEST_DIR, ANSYS_model))
+
+    assert ntw == ANSYS_connection_test   
+
+    # ANSYS Model Export Renomalized to 50 Ohm
+    ANSYS_model_50 = "ANSYS_benchmarks/WEST_capacitor_test_connection_renorm50ohm.s1p"
+    ANSYS_connection_test_50 = rf.Network(os.path.join(TEST_DIR, ANSYS_model_50))
+    ntw.renormalize(50)
+
+    assert ntw == ANSYS_connection_test_50   
+
 
+if __name__ == "__main__":
+    pytest.main([__file__])