**5. Evaluation of basic antenna parameters**

Monopole and dipole antennas are the most basic antennas. Evaluation of the electrical parameters of dipole antenna is used to define basic antenna parameters such as radiation pattern, directivity, and antenna impedance. Dipole antenna is a small wire antenna. It consists of two conductors excited by a voltage fed via a transmission line as presented in **Figure 3**. The center conductor of the transmission line is connected to one of the conductors and the outer conductor is connected to the second conductor. The half-wave dipole consists of two conductors, in which each conductor is approximately quarter wavelength long. We can compute the electromagnetic fields radiated from the dipole by defining a potential function, Eq. (1).

#### **5.1 Dipole antenna**

The electric potential function is *φl*. The magnetic potential function is A. The potential function is given in Eq. (1).

$$\begin{aligned} q\_l &= \frac{1}{4\pi\varepsilon\_0} \int\_c \frac{\rho\_l e^{j(at-\beta R)}}{R} \,\mathrm{dl} \\\\ A\_l &= \frac{\mu\_0}{4\pi} \int\_c \frac{\mathrm{ie}^{j(at-\beta R)}}{R} \,\mathrm{dl} \\\\ \mathbf{Z} &= \frac{\mathbf{A}}{r} \mathbf{Z} \mathbf{I} \\\\ \mathbf{Z} &= \mathbf{P} \end{aligned} \tag{1}$$

**Figure 3.** *Dipole antenna.*
