Muhannad A. Al-Tarifi

Bandwidth Enhancement of the Resonant Cavity Antenna by Using Two Dielectric Superstrates

We propose a novel approach to enhance the bandwidth of the high directivity of the resonant cavity antenna (RCA) by applying two dielectric layers as superstrates. The approach is based on creating two cavities corresponding to two operating frequency bands that combine to form a single wide band of operation. The RCA design is discussed in a methodological manner to determine the thicknesses of the superstrates, the separation distance between them, and the separation distance to the ground plane. We show that the proposed technique is capable of enhancing the bandwidth from 9% of the single superstrate RCA to 17.9% of the two superstrate RCA, with only 0.1-dB reduction of the maximum directivity (17.5 dBi). The presented design method can be replicated for any RCA with any directivity level and type of primary feeding. The performance of the analytically designed antenna is validated by simulation using commercial numerical electromagnetics software.

The Puck Antenna: A Compact Design With Wideband, High-Gain Operation

We develop a high-gain antenna with wideband operation and compact size by placing a small dielectric superstrate (puck) in front of the feeding antenna. The antenna performance is a combination of the leaky-wave effect, naturally existing in this type of antennas, and the edge diffraction effect occurring at the puck perimeter. Compared to the typical resonant cavity antenna utilizing a large superstrate, the proposed puck antenna has nearly four times enhanced performance (gain-bandwidth combination) while using a square puck of side slightly smaller than two wavelengths (at the design frequency). Further enhancement is achieved by making the puck circular in shape in order to add the diffracted fields in phase. The study is conducted through full-wave simulations and validated through measurements in the Ku band. The effect of puck misalignment is then discussed as a potential practical issue. Last, the ground plane is optimized for maximum antenna performance and relatively acceptable values of aperture efficiency (up to 51%).

Bandwidth enhancement of the cavity resonance antenna (CRA) using multiple dielectric superstrate layers

The ray-tracing method is applied to study the radiation of a cavity resonance antenna (CRA) with both single and multiple dielectric superstrate layers. The behavior of the broadside directivity is investigated by analyzing the reflection phase of the antenna superstrates. To enhance the bandwidth of the CRA and maintain its large broadside directivity, a multilayered superstrate of an increasing reflection phase with frequency is presented. When compared to the single-layered CRA, a bandwidth enhancement of more than 100% is attained using a multilayered CRA of three superstrate slabs. Theoretical results are validated by simulations using commercial numerical electromagnetics software.

Multiple superstrates technique for a broadband cavity resonance antenna (CRA)

A cavity resonance antenna (CRA) with three dielectric superstrates is examined and its performance is compared to those of the single superstrate CRAs of the lowest two resonances. The broadside directivity, bandwidth, and directivity-bandwidth product of all three antennas are investigated. When compared to the single superstrate CRAs, an appropriately designed three superstrate CRA can enhance to the maximum directivity, the bandwidth, or both, a result that is reflected as more than 75% increase to the directivity-bandwidth product in some cases. Theoretical results are validated by simulation using commercial numerical electromagnetics software.

Design and Fabrication of a Full W-Band Multi-Step Waveguide 90° Twist

A compact four-step 90-degree waveguide twist is designed for operation over the full W- band. The waveguide cross section is modified from the conventional sharp-corners rectangle to comply with the fabrication constraints. The designed twist is fabricated by two processes; CNC machining of the four steps then assembling, and 3D printing through direct metal laser sintering (DMLS). Both of the realized twists measure better performance than that of the commercially-available longer and more expensive twists. Moreover, they are better suited for integrated systems and delicate machining restrictions in W band.

Application of a dielectric puck for a high gain-bandwidth resonant cavity antenna

We propose a new type of resonant cavity antenna (RCA) that employs a small dielectric puck instead of the large dielectric superstrate layer used in the traditional RCA. The diameter of the puck is studied to determine its influence on the gain-bandwidth product (G·BW) of the RCA. Simulations of the waveguide-fed RCA demonstrate that the G·BW of the RCA with puck can be four times larger than that of the traditional RCA. Moreover, the antenna with puck is compact and can be easily fabricated, which makes it attractive for future high-frequency and very directive point-to-point communication links.

Amplitude-only direction finding using squinted stabilized-pattern horn antennas in W-band

A horn antenna with stabilized radiation characteristics over the entire W-band (75-110 GHz) is used for amplitude-only direction finding. Two horns are squinted in H plane to produce a direction finding function that covers a maximum field-of-view (FOV) with minimum uncertainty (errors). Preliminary results show the systems capability to readily cover FOVs of up to 60° with errors less than ±3°.

45–110 GHz quad-ridge horn antenna

A V-W band quad-ridge horn antenna with stabilized gain and minimum differential E-H plane half power beamwidth (HPBW) is discussed. Multi-step flaring and corrugations on a finite ground plane are applied to achieve required stable gain above 16 dBi from 45 to 110 GHz. The computational studies conducted in HFSS are verified with CST and it is demonstrated that the designed antenna achieves gain variation <; 2 dB, VSWR <; 2:1, difference in E-H plane HPBWs of <; 10°, and acceptable patterns over the entire frequency band.

Two-cavity model for creating two high-directivity bands of the resonant cavity antenna with flexible and dynamic control

We present a simple method to design a resonant cavity antenna (RCA) that resonates in two bands by employing two dielectric superstrates of thicknesses and positions determined by a step-by-step, non-iterative process. The method models the RCA as two cavities, each corresponding to one operational band, which allows for a dynamic control of the separation between the bands. The antenna is analytically designed and performance is evaluated using a commercial software.

Dual-band resonant cavity antenna with a single dielectric superstrate

We present a novel technique to design a dual-band resonant cavity antenna that has only one dielectric superstrate. The technique is based on using a superstrate slab of high permittivity and a thickness of an integer number of half wavelengths. In representative examples, we use a ray-tracing theoretical model to study the dual-band behavior and explain it by observing how the reflection coefficient of the superstrate varies with frequency. The results are validated by simulation using commercial numerical electromagnetics software.