A Miniaturized Half TEM Horn Antenna for UWB Wireless Communication

In this paper, a miniaturized half transverse electromagnetic (TEM) horn antenna is designed for ultra-wideband (UWB) wireless communication. Two radiation modes are generally utilized to extend the impedance bandwidth of traditional TEM horn antennas: one is the combined magneto-electric dipole mode at low frequencies, the other is the TEM horn mode. However, the size of the antenna is relatively big, so the miniaturization is realized by replacing half of the antenna structure with a ground plate to form a half TEM horn antenna. A trapezoidal plate is added to compensate for the magnetic dipoles destroyed by the ground plates to extend the low frequency band while the exponential tapered ridge is used to obtain better impedance match. Besides, an upper ridge contributes to stronger mechanical property. The final configuration whose electrical size is only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${0.6} {\lambda}_{{L}} \ast {0.36} {\lambda}_{{L}} \ast {0.34} {\lambda}_{{L}} ({\lambda}_{{L}}$</tex> being the free-space wavelength at the lowest frequency) is compact and stable enough to be manufactured integrally. The designed antenna has a broad bandwidth from 3 to 12 GHz with the voltage standing wave rate <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$({VSWR}) \leq {2.5}$</tex> and the gain ranges from 4.6 to 9.5dBi.