In this letter, a planar frequency beam scanning antenna (FBSA) with circularly polarized (CP) radiation property is proposed. The beam scans along the narrow side and in lateral plane of the antenna. The antenna consists of two layers: eight periodic symmetrical patches are presented on the top layer as radiation elements to generate CP beam; while microstrip spoof surface plasmon polariton (SPP) transmission line is used as the feeding line, which improves the beam scanning range obviously. The antenna has been fabricated and measured to verify the theory analysis. Measured results indicate that the main beam scans from -5° to +37° in lateral plane within the operating frequency band from 12 to 16.5 GHz, of which excellent CP characteristic is also realized. The peak gain of the antenna is about 9.5dBi over the whole band.

One novel single-feed single-layer wideband circularly polarized (CP) magneto-electric dipole antenna (MEDA) with enhanced gain property is presented in this communication. By loading co-planar spiral with the radiating patch, the unidirectional radiation gain of the antenna is effectively improved while the impedance bandwidth and axial ratio (AR) bandwidth unaffected. Surface current distributions with/without the spiral are compared to reveal the antenna’s mechanism. The measurement shows that the left hand circular polarization (LHCP) antenna features impedance bandwidth from 11.4 to 18.5GHz (or 52%), an AR bandwidth from 13.2 to 18GHz (or 32%), the maximum gain of 11.1 dBic at 16.9 GHz with 3-dB gain bandwidth from 12.5 to 18.6 GHz (or 36.1%). Owning to the low profile, broadband and high gain, the proposed antenna is a capable candidate for satellite communication.

A microstrip antenna with reconfigurable radiation pattern characteristics in the wireless interoperability for microwave access (WiMAX) band is presented. By controlling the states of these four pin diodes, different radiating elements can be activated, which leads to four different radiation patterns for WiMAX application in the 3.44–3.6 GHz range. By sequentially activating the pin diodes, the antenna main beam rotates by 90° in azimuth planes, with 30° deflection in the elevation plane. Moreover, the proposed antenna has a compact structure and good realised gain levels with a minimum value of 8 dBi. The measured results of the fabricated antenna prototype verify the simulation analysis.

In this paper, a low grating lobe array antenna with electrically large property (ELP) is proposed based on TM50 mode square patch antenna elements. By introducing transverse slots on the square radiating patch, four side lobes of the TM50 mode element antenna can be reduced effectively. However, undesired grating lobes are created in the array pattern. That’s because the antenna element distance is more than one wavelength on high modes. In order to solve this issue, a new method is proposed by making the grating lobes of the array factor pattern coincide with the null/(zero) ranges of element pattern. It can effectively suppress grating lobes caused by large element spacing. The method introduced here was supported by analytical 1×2 and 1×4 uniform liner arrays. Meanwhile, in order to further reduce transmission line loss and side lobes, substrate integration coaxial line (SICL) structure and unequal amplitude feeding method are introduced. Finally, a 1×8 liner array is fabricated and measured for verification. When the element spacing is 1.4λ0, the grating lobes level at 22.3GHz is only -22dB.

A planar circularly polarized (CP) frequency beam scanning Fabry-Perot resonator antenna (FPRA) with enhanced gain property is presented in this paper. The antenna consists of two layers. The CP substrate integrated waveguide (SIW) beam scanning leaky-wave antenna (LWA) is used as the feeding antenna. It provides good impedance matching and stable radiation pattern over the working band. Then partially reflecting surface (PRS) layer is introduced to improve gain property by using a single substrate with metal patches array printed on both top and bottom surfaces. After comparisons among four patch types, circular patch type is chosen. It is an ideal choice for CP antenna because of its completely symmetrical structure along ?-plane and gentler phase slope. Parameter analysis is made for better understanding the working principle. Finally, the antenna is fabricated and measured for verification. It shows that the main beam scans from -38° to 28° within the operating frequency band from 9.1 to 14.6 GHz (or 47.8%). 3dB axial ratio (AR) bandwidth is from 10.2 to 13.5 GHz (or 28.7%). Maximum gain is 14.6 dBic and 3dB gain bandwidth is from 11 to 14 GHz (or 26.1%). Gain enhancement of about 3.3~6 dB is achieved compared with the unloaded type. Due to the advantages of high gain, CP beam-scanning capability and easy fabrication, this method is a good option to design antennas in wireless communication and radar systems.