J. Shaker

A Wideband Transmitarray Using Dual-Resonant Double Square Rings

A four-layer transmitarray operating at 30 GHz is designed using a dual-resonant double square ring as the unit cell element. The two resonances of the double ring are used to increase the per-layer phase variation while maintaining a wide transmission magnitude bandwidth of the unit cell. The design procedure for both the single-layer unit cell and the cascaded connection of four layers is described and it leads to a 50% increase in the -1 dB gain bandwidth over that of previous transmitarrays. Results of a 7.5% -1 dB gain bandwidth and 47% radiation efficiency are reported.

Development of a dual band circularly-polarized cassegrain microstrip reflectarray

A design procedure and experimental results are presented for a high-gain dual-band, circularly-polarized (CP) reflectarray antenna with a Cassegrain feed, operating at Ku/Ka-band (Tx=30 GHz, Rx=20 GHz). The performance of this Cassegrain reflectarray antenna is compared with other CP reflectarray antennas designed by the authors of this paper. A transmit gain of 38 dBic and a received gain of 36 dBic with axial ratio of less than 2 dB for both bands was measured for this antenna.

Design of dual-band frequency selective surfaces to block Wi-Fi using printable electronics technology

Design, fabrication and measurement of a special class of engineered surfaces known as frequency selective surfaces (FSSs) is presented in this paper. These FSSs are designed to block the transmission of Wi-Fi signals (2.4 GHz and 5.3 GHz bands) while allowing other portions of the RF spectrum to pass unaffected. Inkjet printing is used to fabricate the FSSs, the details of which will be presented at the conference..

Microwave waveguide transitions using planar anisotropic image guides

We propose a new type of planar guide which can offer advantageous polarization characteristics. Consider an arrangement of sub-wavelength inclusions embedded within a host dielectric. These elements can alter the effective dielectric constant of the slab, and when contained within a fixed width for transmission line applications, a planar dielectric-based guide can be realized that allows for field confinement and power routing. Concepts are extended to new guide transitions. In particular, a 90° corner bend and a waveguide cross-over. These novel routing techniques, which exploit line anisotropy and integration and can offer enhanced data capacity with improved signal integrity, are also applicable to new planar antennas and other printed circuits.

Development of a dual band circularly-polarized offset feed microstrip reflectarray

The design procedure and experimental results are presented for a high-gain, dual-band, circularly-polarized (CP) reflectarray antenna with an offset feed, operating at the Ku/Ka-band (Tx=30 GHz, Rx=20 GHz). The performance of this offset reflectarray antenna is compared with other CP reflectarray antennas designed by the authors of this paper. A transmit band gain of 38 dBic and a receive band gain of 36 dBic both with an axial ratio of less than 3 dB were measured for this antenna.

An antenna for switch beam, multi-beam millimetre-wave cellular systems

This paper presents the design and implementation of a compact, two-dimensional antenna with broadband performance capable of increasing system capacity for next generation 5G base stations. This simple low profile, parallel plate Luneburg lens can be exploited to ensure high energy efficiency, higher data rates, spectral efficiency, and extended coverage leading to a reduction in the number of physical base station antennas, and towers. Inserted between the parallel plates are two identical machined dielectric lens profiles each with a smooth dielectric permittivity gradient, varying from 2 at the center to 1 at the edge corresponding to Luneburg lens design specification. The lens is fed by ultra-low loss open-ended waveguides with probe launchers to inject multiple independent beams at the lens surface and between the plates. The broadband lens has a 3-dB beamwidth of 40° × 5.3° in the E and H plane and an average radiation efficiency greater than 70%. Cross-polarization and port isolation is greater than 30 dB, allowing for the effective co-existence of multiple input beams. The switch beam antenna implementation was optimized to operate in the Ku-band but can be scaled to any suitable mm-wave frequency.

Polarization responsive guides by artificial line anisotropy

The concept of artificial dielectrics has sustained much interest within the electromagnetics community. For instance, compact lenses and polarizers have been designed at microwave and millimeter-wave frequencies along with many other volumetric structures for field control. In these structures an incident wave can be confined and/or transformed due to the periodic loading of sub-wavelength inclusions within a host medium. Most recently these techniques have been adopted to more planar implementations for the routing or tailoring of guided waves. For example, when considering metasurfaces and other transformation electromagnetics-based guides for new transitions and antennas. These engineered materials and surfaces can be characterized using effective material parameters, or more exactly, by permittivity and permeability tensors which may have some spatial dependence.

Applications of periodic structures to modern antenna designs

An overview of the research in the field of periodic structures at Communications Research Centre Canada is presented. The paper covers areas such as: reflectarrays, transmitarrays, artificial dielectric volume holograms, and holographic-based antennas. Achievements, current state of research in each of these areas will be presented.