Yunliang Long

Substrate Integrated Waveguide (SIW) Leaky-Wave Antenna With Transverse Slots

A novel slotted substrate integrated waveguide (SIW) leaky-wave antenna is proposed. This antenna works in the TE10 mode of the SIW. Leakage is obtained by introducing a periodic set of transverse slots on the top of the SIW, which interrupt the current flow on the top wall. It is seen that three modes (a leaky mode, a proper waveguide mode, and a surface-wave-like mode) can all propagate on this structure. The wavenumbers of the modes are calculated theoretically and are numerically evaluated by HFSS simulation. The leakage loss, dielectric loss, and conductor loss are also analyzed. A uniform slotted SIW leaky-wave antenna is designed that has good beam scanning from near broadside (though not exactly at broadside) to forward endfire. This type of SIW leaky-wave antenna has a wide impedance bandwidth and a narrow beam that scans with frequency. Measured results are consistent with the simulation and the theoretical analysis.

Design and Analysis of a Low-Profile and Broadband Microstrip Monopolar Patch Antenna

A new microstrip monopolar patch antenna is proposed and analyzed. The antenna has a wide bandwidth and a monopole like radiation pattern. Such antenna is constructed on a circular patch antenna that is shorted concentrically with a set of conductive vias. The antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the antenna, but also provides a guideline to design a broadband monopolar patch antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi.

Band-Notched UWB Printed Monopole Antenna With a Novel Segmented Circular Patch

A band-notched ultrawideband monopole antenna with a novel segmented radiating patch is presented. Band-notched characteristic in the 5.7-GHz WLAN band is obtained by segmenting a circular monopole patch into three parts. The measured results are in good agreement with the simulated ones. Moreover, the surface current and electric field distributions are analyzed and an equivalent parallel RLC circuit concept is applied to explain the band-notched function. On the basis of the equivalent parallel RLC circuit analysis, the notch frequency and bandwidth of the notched band can be widely adjusted by optimizing the key parameters.

Investigations of SIW Leaky-Wave Antenna for Endfire-Radiation With Narrow Beam and Sidelobe Suppression

A new substrate integrated waveguide (SIW) leaky-wave antenna is investigated for endfire-radiation with a narrow beam and sidelobe suppression. Maximum directivity conditions for endfire-radiation from line sources with different amplitude distributions are theoretically discussed as a design aid. Interestingly, for endfire beams it is seen that designs that have a lower sidelobe level can also have a higher directivity, contrary to what is normally encountered for broadside beams. An SIW leaky-wave antenna with tapered transverse slots on only the top and bottom planes is presented. Compared with a previous leaky-wave antenna having uniform transverse slots on the top plane, the presented leaky-wave antenna has a main beam that can radiate exactly at endfire and also has a lower sidelobe level. The design of the low sidelobe antenna is based on the leaky mode, which loses physical significance as the beam is scanned to the endfire direction. Nevertheless, the antenna retains a good beam shape and a low sidelobe level when it radiates at endfire. A prototype is made, and measured results are consistent with theoretical and simulated results.

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.

Dual-Beam Steering Microstrip Leaky Wave Antenna With Fixed Operating Frequency

A fixed-frequency dual-beam steering microstrip leaky-wave antenna is presented in this paper. A novel equation with finite-difference time-domain method is proposed to calculate the complex propagation constant of microstrip leaky-wave antenna. The microstrip leaky-wave antenna is excited by multiterminals. By control the novel feeding configuration, the microstrip leaky-wave antenna has the advantage of main lobes dual-beam and steering at fixed-frequency. The main lobe steers from 41 to 63 for right beam and from 117 to 139 for left beam symmetrically when operating frequency fixes at 7 GHz. This new microstrip leaky-wave antenna can easily be used as collision avoidance or automobile radar system.

Substrate Integrated Waveguide Leaky-Wave Antenna With H-Shaped Slots

A new leaky-wave antenna based on substrate integrated waveguide (SIW) with H-shaped slots is proposed and investigated. The SIW with H-shaped slots is analyzed as a rectangular waveguide with H-shaped slots. Using an aperture magnetic field integral equation (MFIE), it is found that the SIW with H-shaped slots supports a leaky waveguide mode, a surface-wave mode and a proper waveguide mode depending on frequency. The radiation property is also evaluated using the MFIE. The leaky-wave antenna based on the SIW with H-shaped slots has a narrow beam that scans from broadside to endfire with frequency. The antenna produces an elliptical polarization, including circular polarization. Measured results are consistent with the simulation from HFSS and the theoretical analysis from the MFIE.

The Periodic Half-Width Microstrip Leaky-Wave Antenna With a Backward to Forward Scanning Capability

The periodic half-width microstrip leaky wave antenna (MLWA) with a backward to forward scanning capability is presented in this paper. The proposed antenna consists of a series of half-width MLWA. The radiating periods place on the different sides of the transmission line. The radiating period works in cutoff region of the first higher order mode, the periodic construction radiates the slow wave out along the edge. The experimental results show the main lobe scans electronically and continuously from 149° to 28° in H-plane ( y-z plane) toward end fire (+ z direction) when the operating frequency increases from 4.2-.9 GHz.

Modal Analysis of Dielectric-Filled Rectangular Waveguide With Transverse Slots

The dispersion relations and modes for a dielectric-filled rectangular waveguide with transverse slots are investigated. The differences between the air-filled and the dielectric-filled rectangular waveguides with transverse slots are analyzed. The dielectric-filled rectangular waveguide with transverse slots supports a leaky waveguide mode, a surface-wave mode and a proper waveguide mode. The complex propagation wavenumber is calculated by enforcing an aperture magnetic field integral equation using either a space-domain approach or a spectral-domain approach. The physical significance of the solutions is explained. The theoretical results agree very well with the results from HFSS simulation.

Propagation Wavenumbers for Half- and Full-Width Microstrip Lines in the

Equations are presented for calculating the propagation wavenumbers for half- and full-width microstrip lines operating in the EH1 mode. The transverse resonance method is used for determining the propagation wavenumbers. For the half-width microstrip line, only the self-admittance of the open edge needs to be considered. The self-admittance can be calculated from either the rigorous equations or the simplified formulas, both of which have been derived previously using the Wiener-Hopf method. However, for the full-width microstrip line, the mutual admittance between the two open edges of the microstrip line also needs to be considered. For the first time, the mutual admittance is calculated accurately with the spectral-domain immittance method, and approximately with a space-domain method. By accounting for the mutual admittance, the accuracy of the wavenumber of the full-width microstrip line is greatly improved.