Sidelobe Level In E-plane Research Articles

Dielectric‐loaded substrate integrated waveguide H‐plane horn antenna with embedded air cavity

A new type of dielectric-loaded substrate integrated waveguide H-plane horn antenna with an embedded air cavity is proposed aiming to improve E-plane performance on a thin substrate. Comparing with recent works, this design attracts superior radiation performance only requiring drilling process to embed a rectangular air cavity in the extended dielectric loading. The measurement results show that at 24.15 GHz, the proposed antenna provides a gain of 13 dBi and 27.7 dB front-to-back ratio with narrow 34.3° and 27.3° half-power beamwidths in E- and H-plane. From 22 to 27 GHz, the side lobe level in E-plane is reduced below −10 dB. The entire proposed antenna size is 59 × 16 × 3.175 mm.

Design of a substrate‐integrated waveguide based slot‐pair array antenna for bandwidth enhancement

This study proposes a novel radiating element to enhance the bandwidth of a substrate-integrated waveguide-based resonant slot array antenna. Unlike the conventional scheme, the proposed element has two parallel slots of unequal length. The long slot dominates the radiation, while the short one deals with the matching. An amplitude-tapering power divider was integrated into a 5 × 4 element array to restrain the E-plane sidelobe level (SLL). The measured − 10 -dB bandwidth is 23.14–25.4 GHz (9.42% @24 GHz). The E-plane and H-plane SLLs are − 22.04 and − 30.34 dB, respectively. The cross-polarised levels in the operating band are < − 30 dB and a peak gain of 17.77 dBi was measured at 24.2 GHz. A good agreement is observed between the simulated and measured results and then validates the feasibility of the bandwidth-enhanced slot pair proposed herein.

Sidelobe level reduction using Teflon for a microwave and millimetre‐wave antipodal Vivaldi antenna

A new technique for lowering the sidelobe level (SLL) of the microwave and millimetre-wave antipodal Vivaldi antenna (AVA) has been presented in this study. The technique is based on introducing tapered-shape Teflon surrounding AVA to couple energy propagated from the antenna and produce stronger radiation in the end-fire direction and as a result, it offers wideband low SLL. Some features of the presented antenna with the utilised new technique are summarised as follows: high gain in wide bandwidth corrected tilt of beam on E-plane in wide bandwidth and low cross-polarisation level. The presented antenna is fabricated and the magnitude of the reflection coefficient of the fabricated antenna is tested, which is from 3.2–40 GHz with S11 < −10 dB. It exhibits an average of SLL < −10 dB in E-plane and SLL < −18 dB in H-plane at a wideband of 3.2–40 GHz. Moreover, the lowest E-plane's SLL of −20 dB is achieved over the frequency band of 7–7.5 GHz. The proposed antenna has a small size of 43 (width) × 108 (length) mm2. The proposed antenna with the mentioned features becomes an attractive candidate for imaging applications.

Reduced-Sidelobe Multibeam Array Antenna Based on SIW Rotman Lens

A multibeam array antenna (MAA) fed by a Rotman lens with a reduced sidelobe level (SLL) is designed using a substrate integrate waveguide (SIW) technology. The designed MAA is composed of a Rotman lens and a 12 × 8 slot array, which functions as the beamforming network and the radiation part, respectively. To reduce the SLL in E-plane, dual-port excitations (DPEs) are applied, instead of single-port excitations (SPEs), at each feeding port of the Rotman lens. By using DPEs, a more tapered amplitude distribution can be obtained on the array elements as compared to using SPEs; therefore, the SLL is reduced from about -11 to -18 dB. The SLL in H-plane is controlled by introducing a Chebyshev distribution to the designed eight-element slot array. Based on the designed MAA, a fabricated prototype is measured to test the discrepancy between simulation and experiment.

Suppression of E-Plane Sidelobes Using a Double Slit Layer in a Corporate-Feed Waveguide Slot Array Antenna Consisting of $2\times2$ -Element Radiating Units

The E-plane sidelobe level at tilts around 30°−40° in a Taylor distribution due to tapered excitation of units of $2 \times 2$ radiating slots is suppressed by introducing a double slit layer in a corporate-feed waveguide slot array antenna. The double slit layer act in averaging the excitation of the adjacent radiating slots for the sidelobe suppression and suppression of reflection. A $16 \times 16$ -element array in the 70 GHz band is fabricated. At the design frequency, the sidelobe level at tilts around 30°−40° is suppressed to −30.0 dB from −25.4 dB. Compared to the conventional antenna, the sidelobe levels of the proposed antenna are suppressed over 71.0–76.0 GHz frequencies.

A Low-Profile Wideband Aperture-Fed Microstrip Antenna With Improved Radiation Patterns

A low-profile wideband aperture-fed microstrip patch antenna (MPA) under radiation of TM12 and TM30 modes is proposed with improved radiation patterns. Initially, the radiation characteristic of a rectangular MPA operating in TM30 mode is theoretically investigated. The results demonstrate that its E-plane sidelobe could be gradually reduced by decreasing the resonant frequency of TM30 mode ( ${f} _{30}$ ). As such, a pair of parallel slots is etched out on the radiating patch so as to significantly decrease the ${f} _{30}$ . After that, the MPA under an operation of TM12 mode is further studied. It illustrates that its radiation pattern has the maximum off broadside direction and can be transformed into the broadside radiation by enlarging the length of the parallel slots. In addition, the width of the radiating patch is progressively enlarged in order to reallocate the dual modes in proximity to each other. With these arrangements, a wide bandwidth with improved radiation characteristics is obtained for the antenna under dual resonance. Finally, a prototype aperture-coupled MPA is fabricated and measured. The simulated and measured results agree well with each other, thus demonstrating that its impedance bandwidth is dramatically extended to about 14.8% with a low-profile property of about 0.048 free-space wavelength in thickness. Besides, the antenna has achieved a stable gain varied from 7.0 to 9.9 dBi over the operating band. In particular, the E-plane sidelobe level of the proposed antenna has been successfully suppressed.

Design of an Edge Slotted Waveguide Antenna Array Based on T-Shaped Cross-Section Waveguide

An edge slotted waveguide antenna array based on T-shaped cross-section radiating waveguide is proposed. The T-shaped waveguide is analyzed and designed to operate in dominant mode around the center frequency, which has a lower profile compared with the rectangular one. The radiating slots are etched and rotated alternatively on the broadened top plate without cutting into the adjacent walls. The metal fences are inserted between slots to reduce the mutual coupling and surface wave. Therefore, the sidelobe level in E-plane is well suppressed. A 2 × 8 antenna array working at Ka-band is designed and fabricated. The measured results agree well with simulations which demonstrate this novel waveguide structure.