A compact wideband tunable square ring microstrip antenna

In this paper a new square-ring antenna with tunable operation is proposed. The tuning is achieved using two varactor diodes and an RF switch. The first varactor is connected to a small square patch at one of the square corners to perform the higher band tuning. Another square patch placed inside the square ring is connected to the square ring by an RF switch from one side and to a second varactor from the other side to tune at the lower frequency range. A remarkably wide tuning range in the order of 75% has been achieved using varactor tuning capacitance ration of 10:1.