Ka Ming Mak

A Circularly Polarized Antenna With Wide Axial Ratio Beamwidth

A novel circularly polarized (CP) antenna with wide angular coverage is presented. The proposed antenna is formed by two bowtie patch antennas and two electric dipoles. It can achieve an impedance bandwidth (SWR < 1.6) of 41% and a 3-dB axial ratio bandwidth of 33%. For this design, very stable and symmetrical radiation patterns are obtained. In the axial ratio passband, the 3-dB beamwidth is 85degplusmn2deg with a gain of 6.3 dBi plusmn0.3 dBi. The cross polarization is lower than -15 dB over a wide range of angles. For the entire half-power beamwidth, the axial ratio can be kept below 3 dB.

Circularly Polarized Patch Antenna for Future 5G Mobile Phones

A circularly polarized patch antenna for future fifth-generation mobile phones is presented in this paper. Miniaturization and beamwidth enhancement of a patch antenna are the two main areas to be discussed. By folding the edge of the radiating patch with loading slots, the size of the patch antenna is 44.8% smaller than a conventional half wavelength patch, which allows it to be accommodated inside handsets easily. Wide beamwidth is obtained by surrounding the patch with a dielectric substrate and supporting the antenna by a metallic block. A measured half power beamwidth of 124° is achieved. The impedance bandwidth of the antenna is over 10%, and the 3-dB axial ratio bandwidth is 3.05%. The proposed antenna covers a wide elevation angle and complete azimuth range. A parametric study of the effect of the metallic block and the surrounding dielectric substrate on the gain at a low elevation angle and the axial ratio of the proposed antenna are presented.

Low Cost Dual Polarized Base Station Element for Long Term Evolution

A broadband low profile dual polarized patch antenna for fourth generation long term evolution (4G LTE) is presented in this communication. By employing two wideband feeding mechanisms for the two input ports, a dual polarized patch antenna element with the characteristics of high input port isolation and wide impedance bandwidth is successfully designed. A wide meandering probe (M-probe) and a pair of twin-L-probes are proposed to feed a patch for dual polarization. The proposed design with a wideband balun has impedance bandwidths of over 47% at the two input ports as well as over 37 dB isolation within the entire operating band. Over 8 dBi gain can be achieved at the two ports.

Polarization Reconfigurable Circular Patch Antenna With a C-Shaped

Polarization reconfigurable circular patch antenna with a C-shaped slot is proposed in this communication. It is demonstrated that by introducing a reconfigurable C-shaped slot in a circular patch antenna, the polarization of the radiation of the antenna, operating either in a linearly or circularly polarized mode, can be switched effectively. It is switched between vertical and horizontal polarizations for a linearly polarized mode and switched between left hand circularly polarization and right hand circularly polarization for a circularly polarized mode. The polarization reconfigurable characteristic is realized by controlling the states of the two switching diodes mounted over a concentric circular slot incorporated on the patch, so as to vary the orientation of the C-slot. Prototypes of both linear polarization and circular polarization designs were developed and the performances were validated against measurements. Both antennas exhibit over 20% impedance bandwidth (standing wave ratio (SWR) < 2) and perform broadside radiation over the operating band. The 3-dB axial ratio bandwidth for the circularly polarized case is 4%.

Shorted Bowtie Patch Antenna With Less Susceptibility to Surface Condition

An antenna with less susceptible to surface condition is proposed in this communication. By adding a pair of parasitic shorted patches at the side of a shorted bowtie patch antenna, very low back radiation can be achieved within entire operating bandwidth. Frontto-back ratio, impedance bandwidth and peak gain are over 30 dB, 12.23% and 6.5 dB, respectively, and confirmed by measurement. The proposed antenna has thickness and projection area of only 0.08 λ0 and 0.77 λ0 × 0.77 λ0. A prototype for 5.8-GHz ISM band application (5.725-5.875 GHz) is also designed. Experimental results confirmed that the reflection coefficient, gain, and radiation pattern have been less affected by mounting on different types of surfaces like human wrist, phantom hand, phantom head, or large metal sheet. Its potential applications include 5.8G Wi-Fi, on-body communication, biometric applications, wearable healthcare, and biomedical devices.

Cross slot antenna with very low back radiation for various wireless communications at 5.8GHz ISM band

A new type of cross slot antenna with very low back radiation is proposed in this paper. The proposed antenna has a very low back radiation, which is below -27dB at its center frequency. The antenna is relatively small size, including very low profile and small projection area. Its structure is also very simple and it is very easy to design. The antenna is operated at 5.8GHz, which is the ISM band (5.725-5.875 GHz, which is around 2.6%). Its potential applications include 5.8 GHz Wi-Fi, On-body communication or medical applications.