Shaoyong Zheng

Wideband and Low-Profile Omnidirectional Circularly Polarized Patch Antenna

A wideband low-profile omnidirectional circularly polarized (CP) patch antenna is proposed and investigated in this communication. The design utilizes two monopolar modes of a circular patch which connects to a modified ground plane by a set of conductive vias, to achieve wide-band impedance matching. The curved branches introduced at the edge of circular ground plane excite a degenerate mode and create CP fields. To verify the design, a prototype operating at 2.4 GHz-WLAN band has been fabricated and measured. Measured reflection coefficient, axial ratio (AR), radiation pattern, and antenna gain agree well with simulation results. The proposed prototype has a low profile of 0.024 λ0, a 10-dB impedance bandwidth of 19.8% and a 3-dB AR bandwidth of 19.3%. To further characterize the design concept, a parametric study of the proposed antenna is carried out using HFSS, and general design guidelines are provided.

Broadband Monopolar Microstrip Patch Antenna With Shorting Vias and Coupled Ring

A center-fed circular patch antenna with shorting vias and a coupled annular ring is proposed. With a low-profile configuration, the antenna provides a wide bandwidth by merging three resonant modes, including the TM02 mode of the circular patch, the TM01 mode generated by the shorting vias, and the TM02 mode of the coupled annular ring. The antenna operating in these modes would produce an omnidirectional pattern in the horizontal plane similar to that generated by a monopole antenna. A reduced structure is used to simplify the simulation in optimizing the bandwidth of the antenna. Measured results show that the antenna achieves a bandwidth of 27.4% for a profile of 0.029 wavelengths and has a gain of about 6 dBi.

A Low-Profile Stacked Dielectric Resonator Antenna With High-Gain and Wide Bandwidth

A wideband, low profile and high gain dielectric resonator antenna is investigated in this letter. The antenna consists of two dielectric layers with different permittivities and it is centrally fed by a rectangular slot. By placing the dielectric layer of low permittivity (2.2) below that of high permittivity (15), the antenna with low profile of 0.1λ0 can obtain a 10-dB impedance bandwidth of ~ 40% and an average gain of ~ 9 dBi.

A Compact Filtering Dielectric Resonator Antenna With Wide Bandwidth and High Gain

A rectangular filtering dielectric resonator antenna (FDRA) with low profile, wide bandwidth, and high gain is first investigated in this communication. It is fed by a microstrip-coupled slot from bottom, with open stub of the microstrip feedline elaborately designed to provide two radiation nulls at band edges for a filtering function. A separation is introduced in the slot to provide a good suppression level in lower stopband, while two parasitic strips are parallelly added to the microstrip feedline to offer good suppression in the upper stopband, and consequently, a compact FDRA with a quasi-elliptic bandpass response is obtained without involving specific filtering circuits. Based on the design, a modified DRA fed by a pair of separated slots is proposed to further enhance the gain by ~4 dB. A prototype operating at 5 GHz has been fabricated and measured for demonstration. The reflection coefficient, the radiation pattern, and the antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The prototype has a 10-dB impedance bandwidth of 20.3%, an average gain of 9.05 dBi within passband, and an out-of-band suppression level of more than 25 dB within a wide stopband.

Method of Auxiliary Sources for Analyzing Half-Mode Substrate Integrated Waveguide

A new numerical method based on the method of auxiliary sources (MAS) is presented for analyzing the propagation characteristics of the EH1 mode of a half-mode substrate integrated waveguide (HMSIW). A set of filament auxiliary sources are located on a cylinder surface inside the shorting-via of the HMSIW for representing the current in the shorting-via, and matching points are located on the surface of the shorting-via. Due to the periodicity of the HMSIW, only one period needs to be concerned, and the field resulting from the auxiliary sources in one period is expanded into a series of space harmonics. A transverse equivalent network is introduced to represent the transverse wave of each space harmonic inside the HMSIW, and then the Greens function is deduced. Hence, the propagation wavenumber is calculated accurately and efficiently. The calculated results agree very well with those obtained with other methods.

A Low-Profile Wideband Circularly Polarized Crossed-Dipole Antenna

A low-profile wideband circularly polarized (CP) crossed-dipole antenna that has both wide axial-ratio beamwidth (ARBW) and half-power beamwidth (HPBW) is presented in this paper. The crossed dipoles are composed of four trapezoidal patch arms, and they are fed by a pair of vacant-quarter printed rings to generate CP radiation. Four identical parasitic elements that consist of a horizontal triangle patch and a vertical metallic plate are symmetrically intervened between the crossed dipoles and the ground plane. It has been found that the parasitic elements can effectively decrease the antenna profile, increase the operating bandwidth, and simultaneously enhance the ARBW as well as the HPBW. A prototype was fabricated and measured to verify the design. The measured results show that the prototype has a low profile of

Wideband Circularly Polarized Dielectric Resonator Antenna With Bandpass Filtering and Wide Harmonics Suppression Response

0.1lambda _{0}

Broadband Filtering Dielectric Resonator Antenna With Wide Stopband

, a −10 dB impedance bandwidth of 78.3% and a 3 dB AR bandwidth of 63.4%. Moreover, a 3 dB ARBW of more than 120° and an HPBW of more than 110° are achieved simultaneously within a wide passband of 50.7%.

A Method of Designing a Dual-Band Sector Ring Microstrip Antenna and Its Application

A wideband circularly polarized (CP) dielectric resonator antenna (DRA) with filtering response was proposed in this communication. To combine additional filtering and harmonic suppression functions within an antenna while realizing circular polarization, a new wideband filtering quadrature coupler was implemented to feed a hollow DRA. The filtering quadrature coupler was based on a snowflake shaped patch, whose operating modes can be flexibly controlled by the loading slots. Quarter wavelength coupled line sections were introduced to the coupler, realizing simultaneously wide bandwidth, excellent bandpass filtering, and wide harmonics suppression characteristics. For demonstration, a filtering CP antenna operating at 1.8 GHz was designed, fabricated, and measured. Reasonable agreement between simulated and measured results was observed. The prototype exhibited excellent bandpass filtering characteristics together with a wide overlapping bandwidth of 27.8%, within which the axial ratio value was less than 3 dB, and return loss was better than 12.4 dB. Over the same band, an average gain of 6 dBic with a variation less than 1 dB was achieved. A rejection level larger than 19 dB was found within the suppression band up to the third harmonic.

Periodic Triangle-truncated DSPSL-based Antenna with Back-fire to End-fire Beam-scanning Capacity

A low profile stacked dielectric resonator antenna (DRA) and a microstrip metasurface (MS) antenna are investigated and compared in this communication. It has been found that very similar radiation performance including resonant modes, reflection coefficients, boresight gains, and radiation patterns can be obtained between them, indicating that the dielectric superstrate of stacked DRA plays analogous role with MS in enhancing the antenna bandwidth and realized gain. Based on this observation, a broadband, low profile, and high gain filtering cylindrical stacked DRA is inspired by an MS-based filtering antenna. Four resonant modes including the higher order HEM<inline-formula> <tex-math notation=LaTeX>