Research On Slot Line And Its Application To Slot Antenna

The slot line is formed by cutting a slit in the center of the ground conductor on the side of the dielectric substrate.Due to its low profile,low cost and easy integration,slot line have been more widely used in recent years.This paper studies the addition of slits and loading capacitances based on the traditional slot line,which reduces the wavelength of the wave-guide of the transmission line.The structure is applied to the slot antenna,which provides a theoretical basis for the miniaturization of the antenna.The main work of this paper is as follows:1)A slit-slot transmission line is investigated.Two rows of periodic slits are etched on both sides of metal plate of the traditional slot line.The wavelength of the wave-guide of the new transmission line decreases and the phase constant increases.The equivalent circuit model is given to explain its slow wave characteristics which conforms to the periodic transmission line.The transmission characteristic and propagation constant of the transmission line are studied by the electromagnetic simulation software—HFSS.The effects of the parameters of the slit-slot line on the transmission characteristics are analyzed and the dispersion diagrams are drawn.2)A transmission line with capacitive loading is investigated.A row of periodic capacitances are loaded in the traditional slot line between the center of the slot.Similarly,the wavelength of the wave-guide of the new transmission line decreases and the phase constant increases.The effects of the value and periodic of loading capacitance on transmission characteristics are analyzed and the dispersion diagrams are drawn.3)A miniaturized slot antenna with slits is designed.The two rows of slits are etched on both sides of the grounding plate of the traditional slot antenna.The resonant frequency of the antenna decreases significantly.It is proved that the slits structure can realize the miniaturization of the antenna.To keep the width of the antenna constant and reduce the length of the antenna,both the new and the traditional antenna resonate at 2.45 GHz.Simulation and experimental results show that: The size of miniaturized slot antenna with slits is 32% lower than the traditional antenna,the bandwidth is 210 MHz,the radiation pattern is similar to the half wave dipole antenna,omnidirectional improvement.In addition,the H structure can reduce the lateral dimension of the antenna,one can further reduce the size of the antenna by applying the H structure to the slot antenna with slits.4)A miniaturized slot antenna with capacitive loading is designed.A row of capacitances are loaded in center of the traditional slot antenna,the effect of value on the performance of antenna with capacitive loading is investigated.The results of simulation and measurement show that the antenna can be miniaturized by loading capacitance.