A method to steer the beam of aperture-type antennas is presented in this paper. Beam steering is achieved by transforming phase of the antenna near field using a pair of totally passive metasurfaces, which are located just above and parallel to the antenna. They are rotated independently or synchronously around the antenna axis. A prototype, with a peak gain of 19.4 dBi, demonstrated experimentally that the beam of a resonant cavity antenna can be steered to any direction within a large conical region (with an apex angle of 102°), with less than 3-dB gain variation, by simply turning the two metasurfaces without moving the antenna at all. Measured gain variation within a 92° cone is only 1.9 dBi. Contrary to conventional mechanical steering methods, such as moving reflector antennas with multiaxis rotary joints, the 3-D volume occupied by this antenna system does not change during beam steering. This advantage, together with its low profile, makes it a strong contender for space-limited applications where beam steering with active devices is not desirable due to cost, nonlinear distortion, limited power handling, sensitivity to temperature variations, radio frequency losses, or associated heating. This beam steering method using near-field phase transformation can also be applied to other aperture-type antennas and arrays with medium-to-high gains.

Steering the Beam of Medium-to-High Gain Antennas Using Near-Field Phase Transformation

A novel technique to design a phase-correcting structure (PCS) for an electromagnetic band gap (EBG) resonator antenna (ERA) is presented. The aperture field of a classical ERA has a significantly nonuniform phase distribution, which adversely affects its radiation characteristics. An all-dielectric PCS was designed to transform such a phase distribution to a nearly uniform phase distribution. A prototype designed using proposed technique was fabricated and tested to verify proposed methodology and to validate predicted results. A very good agreement between the predicted and the measured results is noted. Significant increase in antenna performance has been achieved due to this phase correction, including 9-dB improvement in antenna directivity (from 12.3 dBi to 21.6 dBi), lower side lobes, higher gain, and better aperture efficiency. The phase-corrected antenna has a 3-dB directivity bandwidth of 8%.

Dielectric Phase-Correcting Structures for Electromagnetic Band Gap Resonator Antennas

Due to the nonuniform electromagnetic (EM) field amplitude distribution over its aperture, the Fabry–Perot resonator antenna (FPRA) suffers from relatively low aperture efficiency. In this communication, an FPRA with high aperture efficiency is proposed based on a double-layer nonuniform superstrate (DNS). The DNS is designed to have a constant reflection phase but a varying reflection magnitude, thereby obtaining a uniform EM field amplitude distribution over the FPRA’s aperture and, hence improving the directivity and the corresponding aperture efficiency. As an example, a cylindrical FPRA with an aperture diameter of $3.5~\lambda $ (where $\lambda $ is the wavelength in free space) is presented. In comparison with a uniform superstrate, the proposed DNS enhances the FPRA’s directivity from 19.6 to 20.4 dBi and correspondingly improves the aperture efficiency from 76.3% to 91.7%.

Fabry–Pérot Resonator Antenna With High Aperture Efficiency Using a Double-Layer Nonuniform Superstrate

We propose a design for the specific class of trans- verse electromagnetic (TEM) horn that can effectively radiate the electromagnetic signals into soil or concrete. The designed horn antenna has the same aperture height and width, resulting in a square-shaped horn aperture. A design guideline for the horn that considers return loss and radiation performance is described in this paper. The proposed TEM horn is constructed and measured to validate the design. The constructed horn has a maximum dimension (including the balun) of 42.9 × 26.8 × 20 cm. Simulated and measured results suggest that the proposed horn is more effective in radiating electromagnetic energy into concrete, compared with existing TEM horn designs. For free space radiation, measured operating bandwidth of the horn is 0.75-12.0 GHz, with a gain of 3-13 dBi. When radiated into a concrete block, measured operating bandwidth of the horn is 1.0-12.0 GHz.

Design of Transverse Electromagnetic Horn for Concrete Penetrating Ultrawideband Radar

A three-dimensional (3-D) printed Fabry–Perot resonator antenna (FPRA), which designed with a paraboloid-shape superstrate for wide gain bandwidth is proposed. In comparison with the commonly-adopted planar superstrate, the paraboloid-shape superstrate is able to provide multiple resonant heights and thus satisfy the resonant condition of the FPRA in a wide frequency band. A FPRA working at 6 GHz is designed, fabricated, and tested. Considering the fabrication difficulty caused by its complex structure, the prototype antenna was fabricated by using the 3-D printing technology, i.e., all components of the prototype antenna were printed with photopolymer resin and then treated by the surface metallization process. Measurement results agree well with the simulation results, and show the 3-D printed FPRA has a |S11| < −10 dB impedance bandwidth of 12.4%, and a gain of 16.8 dBi at its working frequency of 6 GHz. Moreover, in comparison with the planar superstrate adopted in traditional FPRAs, the paraboloid-shape superstrate of the proposed FPRA significantly improves the 3-dB gain bandwidth from 6% to 22.2%.

https://www.mdpi.com/2076-3417/7/11/1134/pdf

3-D Printed Fabry–Pérot Resonator Antenna with Paraboloid-Shape Superstrate for Wide Gain Bandwidth

A Fabry-Perot resonator excited by a microstrip patch antenna that has a superstrate with a stepped dielectric constant is designed to operate at 5.8 GHz. The antenna is fabricated and is shown to provide enhanced directivity over that achievable using uniform dielectric slabs, with either er = 4.4 or er = 10.2 as superstrates. The measured maximum gain of the patch antenna with a step-index dielectric constant superstrate with a dimension of 2λ0 × 2λ0 was found to be 13.44 dBi, whereas the corresponding values for the uniform dielectric superstrate are 11.25 (er = 4.4) and 12.44 dBi (er = 10.2). As shown in this article, the aperture efficiency of the step-index dielectric is also higher than those of the other two. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:711–715, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26614

Directivity enhancement of fabry‐perot antenna by using a stepped‐dielectric slab superstrate

A wireless security device includes a nonconductive housing, a mother circuit board, a wireless expansion card, and a metal reflector The mother circuit board and the wireless expansion card are disposed in the nonconductive housing The mother circuit board includes a processor The wireless expansion card includes a dielectric substrate, a ground plane, an inverted-F antenna, and an RF (radio frequency) module The metal reflector is positioned between the mother circuit board and the wireless expansion card, and is close to the inverted-F antenna The metal reflector is configured to reduce EMI (Electromagnetic Interference) from the mother circuit board so as to maintain performance of the inverted-F antenna

Wireless security device

A device for enhancing electromagnetic susceptibility comprises a first bridge The first bridge is near to a first trace of a differential pair routing and electrically connects an RF grounding with an analog grounding The RF grounding and the analog grounding are separated The differential pair routing transmits signals between an RF circuit and an analog circuit The first trace of the differential pair routing is closer to an antenna coupled to the RF grounding than a second trace of the differential pair routing The RF circuit is coupled to the RF grounding, and the analog circuit is coupled to the analog grounding

Device and grounding device for enhancing ems and wireless communication device

A 5-element planar dipole array antenna is analyzed and successfully implemented. The proposed antenna is designed for operation at 1.9 GHz band for basic station applications with S 11 < −14 dB. The planar dipole array antenna comprises of a 1×5 dipole array and fed by a microstrip line. This structure is easily constructed by printing on both sides of a dielectric (FR4) substrate. The measured −14 dB return loss (VSWR 1.5:1) impedance bandwidth is around 7.0% (1.79–1.92 GHz). A reflector is put behind the dipole array to obtain directional radiation and high gain, and the measured maximum gain for operating frequencies across the 1.9 GHz band is about 6.9–8.6 dBi. The measured results of radiation efficiency, radiation pattern, antenna gain and return loss show that this dipole array is with a good performance.

Design of high performance sleeve dipole array antenna

In this paper, we show a UWB (Ultra Wide Band) high gain TEM (Transverse Electromagnetic) horn antenna with high directivity efficiency quality in operating bandwidth between 1GHz to 18GHz. Basing on good performance, the antenna can be applied as a feed source of many kinds of measurement systems, and can improve the resolution and contrast of microwave imaging. The measured results show that radiation efficiency is above 70 %, and the peak gain is about 10dBi.

Cheng-Wei Chen

Papers

Directivity enhancement of fabry‐perot antenna by using a stepped‐dielectric slab superstrate

Wireless security device

Device and grounding device for enhancing ems and wireless communication device

Design of high performance sleeve dipole array antenna

UWB balun for TEM horn antenna