Calculate Relative Gain

The relative gain tool calculates offaxis gain based upon the following parameters:

• ${\mathrm{G}}_{\mathrm{rel}}=$ gaiin relative to peak $(\mathrm{dB})$

• ${\theta }_{3\mathrm{dB}}=$ half power beamwidth (deg)

• $\varphi =$ offaxis angle (deg)

Three gain patterns are available:

• Pure parabolic

• Side lobe with 29-25log $(\varphi )$

• Side lobe with 32-25log $(\varphi )$

The sidelobe equations also use the peak gain calculated using the half power beamwidth tool.

These parameters are related using the following equations:

Parabolic:

$$G_{rel,p}=-12{\left(\frac{\varphi }{{\theta }_{3dB}}\right)}^2$$

Sidelobes:

$$\begin{array}{rl}& G_{SL,29}=29-25{\log }_{10}(\varphi )\\ & G_{SL,32}=32-25{\log }_{10}(\varphi )\end{array}$$

Then:

$$G_{rel,SL}=G_{\max }-G_{SL}$$

When the gain pattern is parabolic, the first equation is used. When the sidelobes are used then the gain pattern follows the parabolic equation until it reaches the sidelobe, then continues until the gain $=-10\mathrm{dBi}$.