I am looking forward to solving the integration in the following equation with the assumption that $ka$ is very large
\begin{align}
H = 2jka\int_{-\pi/2}^{\pi/2}\cos{(\varphi-\phi)}e^{jka[\cos{\varphi}+\cos{(\varphi-\phi)}]}\ d\varphi
\end{align}
I used the steepest descent path method to...