# Documentation

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# EHfields

Electric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays

## Syntax

[e,h] = EHfields(object,frequency)
EHfields(object,frequency)
[e,h] = EHfields(object,frequency,points)
EHfields(object, frequency, points)
EHfields(___,Name,Value)

## Description

[e,h] = EHfields(object,frequency) calculates the x, y, and z components of electric field and magnetic field of an antenna or array object at a specified frequency.

example

EHfields(object,frequency) plots the electric and magnetic field vectors at specified frequency values and at specified points in space.

example

[e,h] = EHfields(object,frequency,points) calculates the x, y, and z components of electric field and magnetic field of an antenna or array object. These fields are calculated at specified points in space and at a specified frequency.

example

EHfields(object, frequency, points) plots the electric and magnetic field vectors at specified frequency values and at specified points in space.

EHfields(___,Name,Value) plots the electric and magnetic field vectors with additional options specified by one or more Name Value pair arguments using any of the preceding syntaxes.

Use the 'ElementNumber' and 'Termination' property to calculate the embedded electric and magnetic fields of the antenna element in an array connected to a voltage source. The voltage source model consists of an ideal voltage source of 1 volt in series with a source impedance. The embedded pattern includes the effect of mutual coupling due to the other antenna elements in the array.

## Examples

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Plot electric and magnetic fields of a default Archimedean spiral antenna.

h = spiralArchimedean;
EHfields(h,4e9)

Calculate electric and magnetic fields at a point 1m along the z-axis from an Archimedean spiral antenna.

h = spiralArchimedean;
[e,h] = EHfields(h,4e9,[0;0;1])
e =
-0.4283 - 0.2675i
-0.3047 + 0.4377i
0.0000 - 0.0000i

h =
0.0008 - 0.0012i
-0.0011 - 0.0007i
-0.0000 - 0.0000i

Create an Archimedean spiral antenna. Plot electric and magnetic field vector at the z = 1cm plane from the antenna.

h = spiralArchimedean;

Define points on a rectangular grid in the X-Y plane.

[X,Y] = meshgrid(-.05:.01:.05,-.05:.01:.05);

p = [X(:)';Y(:)';.01*ones(1,prod(size(X)))];

Plot electric and magnetic field vector at the z = 1cm plane. from the antenna

EHfields (h,4e9,p)

Plot the embedded vector fields of a linear array when the first element is excited and all the other antenna elements are terminated using 50-ohm resistance.

l = linearArray;
EHfields(l, 70e6, 'ElementNumber', 1, 'Termination', 50);

## Input Arguments

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Antenna or array object, specified as a scalar handle.

Example: h = spiralArchimedean

Data Types: function_handle

Frequency used to calculate electric and magnetic fields, specified as a scalar in Hz.

Example: 70e6

Data Types: double

Cartesian coordinates of points in space, specified as a 3-by-p complex matrix. p is the number of points at which to calculate the E-H field.

Example: [0;0;1]

Data Types: double

### Name-Value Pair Arguments

Example: 'ScaleFields',[2 0.5] specifies scalar values of the electric and magnetic fields

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value the corresponding value. Name must appear inside single quotes (''). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

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Value by which to scale the electric and magnetic fields, specified as the comma-separated pair consisting of 'ScaleFields' and a two-element vector. The first element scales the E field and the second element scales the H-field. A value of 2 doubles the relative length of either field. A value of 0.5 to halves the length of either field. A value of 0 plots either field without automatic scaling.

Example: 'ScaleFields',[2 0.5]

Data Types: double

Field to display, specified as the comma-separated pair consisting of 'ViewField' and a text input. 'E' displays the electric field and 'H' displays the magnetic field.

Example: 'ViewField', 'E'

Data Types: char

Antenna element in array, specified as the comma-separated pair consisting of 'ElementNumber' and scalar This antenna element is connected to the voltage source.

### Note

Use this property to calculate the embedded pattern of an array.

Example: 'ElementNumber',1

Data Types: double

Impedance value for array element termination, specified as the comma-separated pair consisting of 'Termination' and scalar. The impedance value terminates other antenna elements of an array while calculating the embedded pattern of the antenna connected to the voltage source.

### Note

Use this property to calculate the embedded pattern of an array.

Example: 'Termination',40

Data Types: double

## Output Arguments

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x, y, z components of electrical field, returned as 3-by-p complex matrix in V/m. The dimension p is the Cartesian coordinates of points in space.

x, y, z components of magnetic field, returned as a 3-by-p complex matrix in H/m. The dimension p is the Cartesian coordinates of points in space.