This thesis presents the designs of a multi-band slot antenna, a frequency-reconfigurable (FR) monopole antenna, a frequency-reconfigurable multiple-input-multiple-output (FR MIMO) antenna, a polarization-reconfigurable (PR) monopole antenna, a new metasurface (MS) and a circular-polarization-reconfigurable metasurface (CPR MS) monopole antenna. The multi-band slot antenna consists of a rectangular slot, a T-shaped feeding patch, an inverted T-shaped stub and two E-shaped stubs and has a compact area. The rectangular slot and the inverted T-shaped stub together generate the 1st band. The two E-shaped stubs operating as monopole radiators generate the 2nd band. By using a double-folded stub in the T-shaped feeding patch, two resonant frequencies, i.e., 3rd and 4th bands, can be generated and tuned independently. With this method, the slot antenna can have four operating bands and a size smaller than the previous works. The effect of the feeding cable used in measurement and of the cover used in wireless devices is also investigated. In the FR planar monopole antenna, the radiator consists of two sections, section I and II, which are connected together using a PIN-diode. Section I alone generates a high-frequency band, while section II, when electrically connected together with section I using the PIN-diode, generates a low-frequency band. The radiator of the antenna is meandered for compact size. Continuous tuning of the two operating bands is accomplished by placing a varactor on section I of the radiator, leading to a wide tuning range of 2.39-3.0 GHz. With the use of this technique, a FR monopole antenna and a FR MIMO monopole antenna with wide-continuous tuning are designed. In the FR MIMO monopole antenna, a reconfigurable defected ground structure (DGS) employing two PIN diodes is designed to switch isolation across the whole tuning band. A simple and novel biasing circuit using only three direct current (DC) wires is designed to bias the diodes. The PR monopole antenna consists of two meandered radiators ...