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# Power Budget

To access the **Power Budget** dialog box (see Fig. 1), go to Results > **Power Budget/RCS** in the main menu. The following list of parameters versus frequency is displayed when discrete sources are used for excitation:

- The
**Input Power**column shows the total input power provided by the discrete sources in the structure.

- The
**Radiated Power**column shows the total radiated power from the structure.

- The
**Structure Loss**column shows the total consumed power, representing ohmic losses in the structure.

- The
**Efficiency**column displays the radiated power-to-input power ratio. When the structure is lossless, it results in an efficiency of 100%.

- The
**Directivity**columns display the peak directivity, dimensionless and in decibels (dBi) with reference to an isotropic source.

- The
**Gain**columns display the peak gain, dimensionless and in decibels (dBi) with reference to an isotropic source.

- The
**Av. EIRP**(Effective Isotropic Radiated Power) columns display the average EIRP in Watts and dBW. This value is equal to the Radiated Power.

- The
**Peak EIRP**(Effective Isotropic Radiated Power) columns display the peak EIRP in Watts and dBW.

- The
**Av. Power Density**column is the average power density. This value is calculated averaging the power density over all directions in space.

- The
**Peak Power Density**column is the maximum value of the radiated power density.

- The
**Theta (max)**and**Phi (max)**columns are the zenith and azimuth angles, respectively, in the direction of maximum radiation.

- The
**F/R H**and**F/B H**columns are the**front-to-rear**and**front-to-back ratios**, respectively, in a**horizontal slice**of the radiation pattern given by**Theta = Theta (max)**.

- The
**F/R V**and**F/B V**columns are the**front-to-rear**and**front-to-back ratios**, respectively, in a**vertical slice**of the radiation pattern given by**Phi = Phi (max)**.

- The
**Error**column is the error in the power balance of the system. A necessary, but not sufficient, condition for a model to be valid is that the input power must be equal to the sum of the radiated and lost powers, so the Error is defined as follows:

**Error % = 100 x (Input – Lost – Radiated) Power / (Input – Lost) Power**

- The
**Average Gain Test (AGT)**column represents a similar indicator to the**Error**column. To validate a model, AGT should be close to 1, as it is calculated using the formula:

**AGT = (Radiated + Lost) Power / Input Power**

Select an item from the list in the upper right corner of the window and then press the **Plot** button to plot the selected item versus frequency. Click on the **Export** button to export the list to a CSV file.

Notes

- A power budget
errorof about±10%is permissible from the engineering point of view.

- When a
real ground planeis used, the Error column shows the percentage of power lost in the ground due to its finite conductivity.

- When a
substrate slabis used, this column shows the percentage of power transferred to the dielectric material in the substrate.

AGT = 1means that the power balance is exact. An AGT between0.99and1.01is comparable to achieving an error of ±1%.