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This paper presents a dual-notch polarization and beam reconfigurable microstrip antenna. It uses parasitics which incorporate switches to steer its beam away from boresight and dual notches which, again, incorporate switches to reconfigure between linear and circular polarization. The antenna is a low profile microstrip patch antenna which only uses a single feed, allowing it to be compact and simple in terms of its structure.beam steerable antennas, circular polarization, dual-notch antennas, microstrip patch antennas, polarization reconfiguration | I NT ROD UCTI ONPattern and polarization reconfigurable antennas have received a lot of attention from researchers. More specifically, beam steerable and antennas that can reconfigure their polarization between linear and circular (LP/CP). They can be used for a wide range of applications such as radars, satellite communications and portable devices with satellite communication applications (ie, incorporating GPS receivers). 1 These type of antennas can be used for high data rate applications due to their high gain. Also, beam steering can be used to avoid interference or noisy environments. Simple, compact and high gain single feed beam and polarization reconfigurable antennas are of great significance because they do not need complex feeding networks as conventional circularly polarized antennas need. 2,3 For example, when it comes to portable devices, compact antennas are very important due to size constrains. Furthermore, low power consumption is also very important in such applications. One of the main challenges that beam and polarization reconfigurable antennas impose, is attaining CP and preserving it while reconfiguring the antenna's main beam direction. 4 Furthermore, attaining a good impedance match while reconfiguring between the polarization modes and preserving a good alignment between the 10 dB return loss bandwidth and the 3 dB AR bandwidth are also challenging. 2,3 This paper presents a solution which uses parasitics to steer the beam away from boresight, and dual-notches to attain CP within a steering range of the antenna. Preserving CP has been especially challenging in this design, where parasitics are used for beam reconfigurability, which affect the resonant frequency of the antenna. It was also challenging to attain a good alignment between the 10 dB return loss and the 3 dB axial ratio (AR) of the antenna while switching ON and OFF different pairs of parasitics.

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This paper presents a novel antenna which represents an alternative to conventional phased array antennas. The novel antenna offers three important advantages in comparison with a conventional phased array antenna. These advantages are as follows: i) it is able to steer the beam to relatively wide angles (±31 0 ), ii) it maintains low side-lobe level of < −10 dB across the steering range and iii) it achieves gain stability over the steering range. It also demonstrates relatively high gain (≈ 15 dB) to meet the demand of high capacity and long range in wireless communication applications. The proposed array antenna involves the use of parasitic elements and phase shifters.

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