Research On Reconfigurable Antenna With Multi-beam And Multi-frequency

As a novel antenna, reconfigurable microstrip antenna has many advantages, such as lighter weight, lower profile and can be integrated more easily, so it has become one important antenna pattern and drawn much attention. Multi-beam and multi-frequency reconfigurable antenna not only is of the frequency reconfigurable antenna's merits but also pattern reconfigurable antenna's merits, which has become a direction in the field of reconfigurable antenna research.In this thesis, three microstrip antennas with frequency and pattern reconfigurable characteristics are designed. Firstly, a pattern and frequency reconfigurable microstrip antenna with the symmetrical structure is proposed. By controlling the states of the corresponding switches, the designed antenna can operate at three frequency-bands of 2.11-2.26 GHz, 2.28-2.52 GHz and 3.73-4.02 GHz. The radiation pattern can be switched with the pattern of reverse symmetry at the operating bands. Then, a novel planar circular reconfigurable microstrip antenna with six switchable lobe patterns is designed. The antenna has a available impedance bandwidth of 2.33-2.49 GHz. By changing the connection between the radiators and feed, six reconfigurable lobe patterns with the half power beamwidth about 60 o are achieved. The patterns can be scanned in azimuth plane.Finally, a novel planar parasitic array antenna with reconfigurability in both frequency band and radiation pattern is proposed. It consists of six symmetrically reconfigurable radiating elements and six symmetrically reconfigurable parasitic elements. RF P-I-N diodes are used to switch the radiation structure and change the current distribution, which leads to twelve different radiation patterns and two frequency bands within 2.28-2.58 GHz and 2.62-2.73 GHz respectively. The novel antenna can provide reconfigurable azimuth pattern with the beamwidth of about 67 o and 54 o. The proposed array antenna has potential applications in diversity wireless communication system..The proposed reconfigurable array microstrip antenna is fabricated and measured. The measured and simulated results agree well with each other, which verify the correctness and feasibility of antenna design.