This paper presents the design of a logarithmic array of microstrip nano-antennas at terahertz frequencies. For applications in which small antennas are required, microstrip antennas are preferred. However, they have a narrow bandwidth. To overcome this problem in microstrip antennas, a log-periodic nanoantenna design is presented which exhibits a wide bandwidth and ultra-compact design. This antenna is smaller in size compared to log-periodic antennas in microwave bands and comparable and better radiation characteristics. The proposed Log-periodic microstrip nanoantenna array consists of seven patch elements on a dielectric layer and are fed directly by a feed line through the branch lines connected to each of the elements. Scaling factor, τ = 0.95 is considered for this design and inset feed is used. In this structure, the substrate has a relative dielectric constant of εr = 4.4 and a thickness of h = 800 nm. For good performance at high frequencies, gold is used for the design of the antenna. The considered operating frequency is 3.3 THz corresponding to a wavelength of 91 µm. Good impedance matching and a wide bandwidth of 800 GHz is obtained.
