- #1

- 312

- 0

**Statement:**

Consider two dipole antennas, oriented 90degrees apart [imagine the x-y plane, let "a" be the dipole oriented along the x-axis, and the "b" be the dipole oriented along the y-axis]. If "a" dipole radiates [tex]cos(\omega t)[/tex] and "b" dipole radiates [tex]sin(\omega t)[/tex], the field radiated by the two antennas will be circularly polarized:

[tex]\vec{E}(z, t) = E_{0}[cos(\omega t - \beta z)\hat{x} + sin(\omega t - \beta z)\hat{y}][/tex] (#1)

Side note: Very often, helical antennas are used to generate a circularly-polarized (CP) wave. The isolation between a left-handed CP wave and a right-handed CP wave can be significant. Also, a CP wave will change handedness upon reflection.

**My thoughts:**

I understand that [tex]E_0[/tex] is the magnitude of the sinusoid- and in this case it is circular thus both [tex]\hat{x}, \hat{y}[/tex] have the same amplitudes respectively. And since both [tex]sin(\omega t), cos(\omega t)[/tex] are perpendicular to one another, if one has a phase shift, the other will have the same phase shift [tex]\beta[/tex].

**Relevant questions:**

Is my thoughts above reasonable? What I would really like to know is why the electric field is a function of z also. What is the variable z, and how does it influence the electric field?

Also, can someone explain to me what is meant by

Also, a CP wave will change handedness upon reflection?

Thanks,

Jeffrey