: The development of high definition audio/video signals and the growing number of communicating devices in homes and small offices have recently increased the demand for high data rate wireless communication in short ranges. The mm-wave frequency band offers a wide bandwidth allowing data rates of up to 5 Gbits/sec. Among various mm-wave frequency bands, the 60 GHz band has special properties, making it more appropriate for wireless communications in short ranges such as WPAN. The most important reason is its overlap with the oxygen absorption resonance range. Due to the strong absorption, as well as the large free space attenuation, the 60 GHz band provides interference-free closely spaced coverage areas. In 60 GHz short range applications, high gain and broadband antennas are necessary. Dielectric rod antennas, acting as end-fired surface-wave antennas or leaky wave antennas, have been known for quite some time. They radiate by converting guided waves of the dielectric rod into free space propagating waves. Despite numerous applications of rod antennas, the existing theoretical design guidelines are oversimplified. Instead, a number of rigorous numerical methods, such as FDTD, FEM and integral equation based methods have been utilized to study the radiation characteristics of dielectric rod antennas. Although these methods are accurate, they are often too complex and computationally intensive and offer little insight into the underlying working mechanism. In this thesis, a semi-analytical method based on local mode theory is presented for analyzing tapered circular and rectangular dielectric rod antennas. In this approach a simple volume integral equation with point matching solution is used to analyze the tapered dielectric rod antenna. However, the method uses the so-called local mode theory to determine the appropriate basis functions for the polarization current distribution in the dielectric region and, after applying the method of moments, utilizes the equivalence principle to calculate the far-field radiation pattern from this current distribution. The method results in a formula for the radiation pattern that needs only simple integrations over the cross section of the antenna. The use of both equivalent volume current distributions with a local mode approximation for the fields in the tapered dielectric region provided a fairly accurate and computationally efficient method for computation of the radiation pattern for tapered circular dielectric rod antennas. This method can be used efficiently for the design and optimization of such antennas. But for tapered rectangular dielectric rod antennas, because of using Marcatili’s method to approximate basis functions for the polarization current distribution, the results are not as accurate. Fundamental radiating mechanism of dielectric rod antennas is discussed and guidelines to achieve maximum gain are given. Furthermore, dielectric loss is calculated and it is shown that, by increasing the permittivity of the dielectric medium, dielectric loss is increased. So as the antenna size increases, the dielectric permittivity should be decreased in order to maintain radiation efficiency. It is shown that by using periodically tapered dielectric rod antennas higher gain and radiation efficiency can be achieved. Keywords: Tapered dielectric rod antennas, millimeter waves, surface wave antennas, local mode theory, volume integral equation, body of revolution.