Abstract-This paper presents a novel method to enhance the pattern characteristics of the TEM horn antenna for 2-14 GHz frequency band. The conventional TEM horn antenna introduces some fluctuations in the main lobe radiation pattern over the higher frequencies, i.e., 10-14 GHz. This motivated us to propose a new method to remove the aforementioned impact by carving an arc shape to the open end of exponentially tapered plates. The associated curvature of this arc is optimized to completely remove the fluctuation. The measurement results show that the improved TEM horn antenna structure exhibits low VSWR as well as radiation pattern over 2-14 GHz frequency band.

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This article describes a new technique for pattern squint elimination of quadridged conical and pyramidal horn antennas by introducing bended coaxial probes. Because of the phase difference and mutual coupling between vertical and horizontal polarizations, the radiation patterns of the conventional quad-ridged conical and pyramidal horn antennas squint over a wide bandwidth. The proposed technique substantially reduces the phase difference and coupling between the two probes, so a significant improvement in the radiation patterns over the frequency band of 8-18 GHz can be achieved. The designed modified horn antennas are most suitable as a feed element in reflectors of radar systems and EMC applications. The proposed modified antennas have a voltage standing wave ratio (VSWR) less than 2.2 for the frequency range of 8-18 GHz. Moreover, the proposed antennas exhibit high gain, dual-polarization performance, good isolation, low SLL, low back lobe, low cross polarization, and satisfactory far-field radiation characteristics for the entire frequency band. V C 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 20: 94-102, 2010.