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Lumped element circuit to load antenna


le = lumpedElement creates a lumped element circuit. The default value is an empty lumpedElement object.

When you load an antenna using a lumped resistor, capacitor, or inductor, the electrical properties of the antenna change. These lumped elements are typically added to the antenna feed. You can use lumped elements to increase the bandwidth of the antenna without increasing the size of the antenna.


le = lumpedElement(Name=Value) returns the lumped element circuit based on the additional options specified by one or more name-value arguments.


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Create a resistor with 50 Ohms of impedance. Any pure resistive load has a nonvariable impedance when the frequency changes.

le = lumpedElement(Impedance=50);

Create a dipole antenna. Calculate the impedance of the antenna without loading the antenna.

d = dipole;
i1 = impedance(d,70e6)
i1 = 72.9851 - 0.4727i

Load the antenna using a frequency-independent resistor. Calculate the impedance of the antenna.

d.Load = le;
i1e1 = impedance(d,70e6)
i1e1 = 1.2299e+02 - 4.7272e-01i

Change the frequency to 85 MHz and calculate the impedance of the antenna.

ile2 = impedance(d,85e6)
ile2 = 2.2370e+02 + 1.1331e+02i

Create a dipole antenna using one load at the antenna feed and one load at a location above the antenna feed.

Create a dipole antenna.

d = dipole;

Create two lumped elements to load the dipole antenna.

One lumped element of impedance, 50 Ohms, loads the antenna at the feed.

l1 = lumpedElement(Impedance=complex(50,-20),Location="feed");

The second lumped element of complex impedance, 50 + j*20 Ohms, loads the antenna at the top. Locate the load half distance from the feed.

l2 = lumpedElement(Impedance=complex(50,-20),Location=[0 0 0.5]);

Add the two loads to the dipole antenna.

 d.Load = [l1, l2];

View the dipole antenna.


Input Arguments

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Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: Frequency=2e9

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'Frequency',2e9

Complex impedance of circuit, specified as a real or complex vector of z-parameters in ohms.

Example: Impedance=complex(75,30) specifies a complex impedance of 75+i30.

Data Types: double

Frequency of operation of the lumped element, specified as a real vector in Hz. This operating frequency range must match with the operating frequency range of the antenna loaded by this lumped element.

Example: Frequency=[10e6,20e6,30e6]

Data Types: double

Location of load, specified by Cartesian coordinates. The default location of the lumped element is at the antenna feed (x=0, y=0, z=0).

Example: Location=[0 0 0.5]

Data Types: double

Output Arguments

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Lumped element, returned as a lumpedElement object. The real part of the complex number indicates the resistance. The imaginary part of the complex number indicates the reactance.

Version History

Introduced in R2016b

See Also