Substrate Integrated Waveguide Frequency-Agile Slot Antenna and Its Multibeam Application

A new technique for designing the substrate integrated waveguide (SIW) frequency-agile slot antenna is presented in this paper.Similar to the metallic waveguide counterpart, the SIW is a uniconductor guided-wave structure and inherently difficult in the electronically tunable applications.To solve this problem, a single slot etched on the top conductor layer of a conventional antenna is instead of two slots to construct an isolated area, which is convenient for the DC bias.The electric length of slots can then be adjusted through two shunt varactors welded near the center of slot.As such, a SIW frequency-agile slot antenna is realized and fabricated to cover the frequency of 2.30 ∼ 2.74 GHz with different bias voltages.Experiments verify our theory analysis and design process.Then, a frequency-agile multibeam antenna is developed to cover several frequency bands while switching between four different radiation patterns pointing at different spatial locations for each frequency.It presents an excellent candidate for software and cognitive radio system applications.