What is an E-field Generator?
An E-field generator is a type of antenna (dipole, biconical, horn, or microstrip) used to convert RF power received from a power amplifier into Electromagnetic waves. It creates the required electric field strength (V/m) as per the EMC radiated immunity/emission testing standards. During the EMC immunity test, E-field generators are used to create the required field strength over a wide range of frequencies in an anechoic chamber or open area test site (OATS).
Fig. 1 E-field generator
Fig. 2: Immunity test setup
How Does an E-Field Generator work?
When a sinusoidal signal at a certain frequency is applied to the dipole antenna, it results in back and forth movement of the electrons (charges) from one end of the antenna to the other end which causes dipole conductors (capacitor plates) to get charged alternatively (positive and negative). This cumulative action of electrons leads to the electric field propagating out from the antenna, and the movement of the electron creates a current (charging current) that results in magnetic field lines encircling the current-carrying dipole conductors. As the source signal is oscillating, there will be a creation of time-varying electric and magnetic fields between the conductors forming electromagnetic waves propagating into the space in a circular fashion.
The electric field pattern between the capacitor plates when the charges are placed on each of the plates is shown in figure 4. The electric field lines start with a positive charge and end with a negative charge. The two conductors of the dipole antenna act like the plates of a capacitor.
Fig. 5: Showing intrinsic capacitance and charging current
Fig. 6 : E-field
Fig. 7: H-field
Fig. 8: Electromagnetic Wave from dipole to space
What to look for in an E-Field Generator:
Represents the power requirement of the E-field generator to establish specified field strength (V/m) in the EMC site. It is usually in the KW range.
Operational frequency range: Represents the operational frequency range of the E-field generator. Usually, E-field generators have a frequency range from a few kHz to GHz.
Typical Field Strength: Represents the field strength provided by the generator at a given input power level. It is represented in V/m at KW.
Input Impedance: Represents the input impedance of the E-field generator in ohms. It is usually 50 ohms.
VSWR: Represents the measure of how efficiently radio-frequency power is transmitted from the power amplifier into the input terminal of the E-field generator (antenna). A low input VSWR is the indication of a good E-field generator.
Connector Type: Represents the connector type available with E-field generator. Usually, it is an N-type.
Maximum Test Object Volume: Represents the maximum test object volume that can be efficiently radiated to by the e-field generator. It is represented in L × W × H.
Elemental Dimension: Represents the elemental dimension of the E-field generator.
EMC Directory has listed E-Field Generators from the leading manufacturers and has made them searchable on the website. Use the filters to narrow down on E-Field Generators based on the frequency, E-Field strength required and various other parameters. View product details, download datasheets and get quotes.