An isotropic antenna element radiates equal power in all nonbaffled
directions. To construct an isotropic antenna, use `phased.IsotropicAntennaElement`

.
When you use this object, you must specify these aspects of the antenna:

Operating frequency range of the antenna

Whether the response of the antenna is baffled at azimuth angles outside the interval [–90,90]

You can find your isotropic antenna element's voltage
response at specific frequencies and angles using the antenna element's `step`

method.

This example shows how to construct a backbaffled isotropic antenna element with a uniform frequency response over azimuth angles from [–180,180] degrees and elevation angles from [–90,90] degrees. The antenna operates between 300 megahertz (MHz) and 1 gigahertz (GHz). Plot the antenna response at 1 GHz.

ha = phased.IsotropicAntennaElement(... 'FrequencyRange',[3e8 1e9],'BackBaffled',false) plotResponse(ha,1e9,'RespCut','3D','Format','Polar',... 'Unit','pow');

`plotResponse`

is a method
of `phased.IsotropicAntennaElement`

. By default, `plotResponse`

plots
the response of the antenna element in decibels (dB) at zero degrees
elevation.

figure; plotResponse(ha,1e9);

Setting the `BackBaffled`

property to `true`

limits
the response to azimuth angles in the interval [–90,90].

ha.BackBaffled=true; figure; plotResponse(ha,1e9,'RespCut','3D','Format','Polar',... 'Unit','pow');

This example shows how to design a backbaffled isotropic antenna element and obtain the response of that element.

Construct an isotropic antenna element to operate in the IEEE^{®} X
band between 8 and 12 GHz. Backbaffle the response of the antenna.
Obtain your antenna element's response at 4 GHz intervals between
6 and 14 GHz and at azimuth angles between –100 and 100 in
50-degree increments.

ha = phased.IsotropicAntennaElement(... 'FrequencyRange',[8e9 12e9],'BackBaffled',true) respfreqs = 6e9:4e9:14e9; respazangles = -100:50:100; anresp = step(ha,respfreqs,respazangles)

The antenna response in `anresp`

is a matrix
whose row dimension equals the number of azimuth angles in `respazangles`

and
whose column dimension equals the number of frequencies in `respfreqs`

.

The response voltage in the first two and last two columns of `anresp`

is
zero because those columns contain the antenna response at 6 and 14
GHz respectively. These frequencies are not included in the antenna's
operating frequency range.

Similarly, the first and last rows of `anresp`

contain
all zeros because the `BackBaffled`

property is
set to `true`

. The first and last row contain the
antenna's response at azimuth angles outside of [–90,90].

To obtain the antenna response at nonzero elevation angles,
input the angles to `step`

as a 2-by-M matrix where
each column is an angle in the form `[azimuth;elevation]`

.

release(ha) respelangles = -90:45:90; respangles = [respazangles; respelangles]; anresp = step(ha,respfreqs,respangles)

Note that `anresp(1,2)`

and `anresp(5,2)`

represent
the antenna voltage response at the aziumth-elevation pairs (–100,–90)
and (100,90). Because the elevation angles are equal to +/–
90 degrees, these responses are equal to one even though the `BackBaffled`

property
is set to `true`

. Thus, the resulting elevation
cut degenerates into a point.

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