FEMTEC 2013 May 23, 2013, Las Vegas Optimization of Electrical Properties of Parallel Plate Antenna for EMC Testing Zdeněk KUBÍK, Denys NIKOLAYEV, Pavel KARBAN, Jiří SKÁLA, Miroslav HROMÁDKA University of West Bohemia Faculty of Electrical Engineering

Abstract The major application of a parallel plate antenna (also called: TEM-cell, strip line antenna, etc.) is the radiated immunity and interference testing for EMC applications. Appropriately designed antenna represents a transmission line with TEM wave propagation and uniform electromagnetic field distribution between plates. Device under test (DuT) is positioned within the region of uniform EM field. In this presentation, we will discuss the optimization of electric properties of a small parallel plate antenna, which was designed for RF radiated immunity testing of telecommunication appliances. We conducted numerical based optimization to improve TEM-cell parameters. Results were verified by experiments.

Introduction Electromagnetic compatibility background Majority of all modern devices use electronic circuits All devices interact with surrounding—including other electronic devices and human bodies Four types of interaction: 1. Conducted emission 2. Conducted susceptibility 3. Radiated emission 4. Radiated susceptibility

Introduction EMC immunity testing of electronic devices Usually is performed in an anechoic chamber, E field is generated by a transmitting antenna Parallel plate antenna (strip line, TEM cell, …): Usually is performed in an anechoic chamber, E field is generated inside PPA (TEM wave) Fig.1: Free space propagation of the EM wave

Introduction Microstrip line impedance Impedance depends on height, width of a microstrip and effective permitivity Electric field inside a microstrip

Introduction Scattering parameters or S-parameters depict the electrical behaviour of a passive elements where a denotes an incident wave and b represents reflected wave S11 parameter (reflection coefficient )

RL Measurement Return loss—RL RL measurement

Problem Goal: Optimize the electrical properties of parallel plate antena for EMC testing

Original Stripline Dimensions of the stripline: W = 300 mm H = 400 mm Impedance of the stripline: Z0 = 141 Ω

3D FEM Model Wave equation to be solved: Boundary conditions Impedance boundary condition: Scattering boundary condition: Lumped ports DoFs: ~1.2 MEG

Results Dependence of RL on frequency: original PPA

Results Dependence of RL on frequency: Z0 parameter

Improvement Stripline Improvement: new impedance matching and terminator SMD resistors were used Disadvantage: low power load

3D FEM Model Wave equation to be solved: Boundary conditions 1) Impedance boundary condition: 2) Scattering boundary condition: 3) Lumped ports 4) PMC for the symmetry BC DoFs: ~1.7 MEG

RESULTS Dependence of RL on frequency: optimized PPA

RESULTS Dependence of RL on frequency; parameter: angle of feeding taper Problem: distribution of E on the bend of a plate

RESULTS Distribution of E on bend of plate: 15°, 30°, 45° and 60°

Comparison Comparison of original and optimized PPA

Conclusions 3D FEM models were used for parallel plate antenna (PPA) simulations The original PPA was optimized using FEM RL improvement: approx. -15 dB Analysis of RL dependence on termination impedance Analysis of RL dependence on feeding taper angle FEM models results were verified by measurement Future research needs New impedance coupling and termination Difference between resistors impedance matching and balun (transmission line transformer) Design of large PPA (width and height approx. 0.8 m, length approx. 2.5 m) Simulations of S21 parameter – dependence of S21 on PPA filling (DuT)

Thank you for your attention FEMTEC 2013 May 23, 2013, Las Vegas Thank you for your attention Optimization of Electrical Properties of Parallel Plate Antenna for EMC Testing Zdeněk Kubík zdekubik@kae.zcu.cz www.fel.zcu.cz University of West Bohemia Univerzitni 26 306 14, Plzen Czech Republic