A Modified TEM Horn Antenna Customized for Oil Well Monitoring Applications

A TEM horn antenna with modified radiation pattern customized for oil well monitoring application is presented in this paper. The antenna is designed to operate in an oil saturated medium in the frequency range between 1.4 to 11 GHz. A complete design procedure for the proposed TEM horn antenna with a method to modify the radiation pattern is introduced here. The modification is conducted using nonuniform expansion of the antenna flares. Applying this technique eliminates ripples in the antenna´s main-lobe radiation pattern at higher frequencies, a problem which exists for conventional TEM horn antennas. The design coefficients which control the flare openings are optimized using CST Microwave Studio to achieve smooth main-beam radiation patterns while maintaining return loss more than 10 dB. Simulations are performed both in oil and free space. Free space simulations are done to provide a valid reference for antenna radiation pattern measurement as radiation pattern cannot be measured in oil. Simulation results are followed by the measurement results with a very good agreement. The fabricated dimensions of the antenna including balun section are limited to 89.2×49.2×78.2 mm. The designed antenna is utilized as a part of an ultrawideband radar system for oil well monitoring.