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.

EHfields(object,frequency) plots the absolute values of the electric and magnetic field vectors along with corresponding signed complex angles at the specified frequency values and at the specified points in space. The multiplication factor with absolute field value is +1 for positive and -1 for negative complex angle.

[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.

EHfields(object, frequency, points) plots the absolute values of the electric and magnetic field vectors along with corresponding signed complex angles at specified frequency values and at specified points in space. The multiplication factor with absolute field value is +1 for positive and -1 for negative complex angle.

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

Plot E and H Fields of Antenna

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

h = spiralArchimedean;
EHfields(h,4e9)

Calculate EH Fields of Antenna

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 = 3×1 complex

   0.4137 + 0.2557i
   0.3040 - 0.4084i
   0.0000 + 0.0000i

h = 3×1 complex

  -0.0008 + 0.0011i
   0.0011 + 0.0007i
  -0.0000 - 0.0000i

Plot Electric and Magnetic Field Vector of Antenna

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);

Add a z-offset of 0.01.

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)

Embedded Vector Fields of Linear Array

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);

Calculate the Electric and Magnetic Fields at Multiple Frequencies at Single Point in Space

Calculate electric and magnetic fields of a dipole antenna.

[E H] = EHfields(dipole, 70e6:2e6:80e6, [0 0 0]')

E = 3×6 complex

   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i
  -0.0242 + 0.0030i  -0.0251 + 0.0028i  -0.0263 + 0.0025i  -0.0277 + 0.0023i  -0.0292 + 0.0021i  -0.0308 + 0.0020i
  -1.5494 - 1.9676i  -1.8677 - 1.6821i  -2.0155 - 1.3838i  -2.0573 - 1.1327i  -2.0447 - 0.9371i  -2.0075 - 0.7881i

H = 3×6 complex
10-3 ×

  -0.6066 + 0.0834i  -0.5235 + 0.1859i  -0.4344 + 0.2367i  -0.3583 + 0.2546i  -0.2985 + 0.2554i  -0.2525 + 0.2482i
   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i   0.0000 - 0.0000i
   0.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i

Input Arguments

object — Antenna or array object

scalar handle

Antenna or array object, specified as a scalar handle.

Example: h = spiralArchimedean

Data Types: function_handle

frequency — Frequency used to calculate electric and magnetic fields

scalar | vector in Hz

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

Example: 70e6

Data Types: double

points — Cartesian coordinates of points in space

3-by-p complex matrix

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.

'ScaleFields' — Value by which to scale electric and magnetic fields

two-element vector

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

'ViewField' — Field to display

'E' | 'H'

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

'ElementNumber' — Antenna element in array

scalar

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

'Termination' — Impedance value for array element termination

50 (default) | scalar

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

e — x, y, z components of electrical field

3-by-p complex matrix in V/m

x, y, z components of electrical field, returned as 3-by-p complex matrix in V/m. The dimension p is the number of points in space at which the electric and magnetic fields are computed.

h — x, y, z components of magnetic field

3-by-p complex matrix in A/m

x, y, z components of magnetic field, returned as a 3-by-p complex matrix in H/m. The dimension p is the number of points in space at which the electric and magnetic fields are computed.