Normalization
Selecting Graph - Graph Options - Normalization from the Far Field Pattern Tab main menu allows you to select the type of normalization to use for your plot. Once a normalization type is selected, all curves use that normalization.
You may choose between three types of normalization: Power Gain (dB), Directive Gain (dB), or Power/EMC. By default, the Far Field Pattern Tab displays the Gain (dB). You select the type of normalization by clicking on the appropriate radio button.
Power Gain (dB)
The power gain is defined as the radiation intensity divided by the uniform radiation intensity that would exist if the total power supplied to the antenna were radiated isotropically. [1]
Include Reflection: Select this checkbox to base the gain calculation on the total available power at the source rather than the total power delivered to the load.
Directive Gain (dB)
Directive gain is defined as the radiation intensity from an antenna in a given direction, divided by the uniform radiation intensity for an isotropic radiator, with the same total radiation power. [2]
The Far Field Viewer calculates the directive gain based on the total power radiated by your circuit. It calculates the total power by using all the theta (θ) and phi (ϕ) points to integrate over the entire surface. Therefore, the more theta and phi points calculated, the more accurate the values are provided for the directive gain. A Figure of Merit (F.O.M.) appears in this dialog box and in the normalization panel when directive gain is selected to provide you with an idea of the accuracy of the data (100% is perfect). If this figure is too low, try recalculating it using more theta and phi points. If this figure is too high, it is an indication that the problem is over calculated. i,e, angles are being analyzed twice. In this case, check for duplicate angles such as theta = 180 and theta = -180.
Power/ EMC
Selecting the Power/ EMC for the normalization displays the power at a given angle.
Absolute Unit: You may display the power in Watts/ Steradian, Volts/Meter at a distance of 3 M and Volts/Meter at a distance of 10 M.
Relative to setting
This section is only available for Power Gain and Directive Gain normalizations.
Relative to: A reference point from which the gain is calculated. The choices are:
- Isotropic: Normalizes the data to a theoretical isotropic antenna in free space.
- Arbitrary: Normalizes the data to an arbitrary value which you enter in the Reference Value text entry box.
Reference Value: The value provides the reference point in dB for the normalization when using the arbitrary setting.
References
[1] Simon Ramo, John R. Whinnery and Theodore Van Duzer, Fields and Waves in
Communication Electronics, John Wiley & Sons, Inc. 1994, pg. 601.