A. Dubok

Miniaturization of Robust UHF RFID Antennas for Use on Perishable Goods and Human Bodies

Design guidelines for electrically small and robust UHF radio frequency identification (RFID) antennas are derived for operation in complex environments, such as perishable goods (e.g., meat and milk) or human bodies. A prototype UHF RFID antenna tag with an embedded integrated circuit (IC) is developed and tested in an RFID system. Water and meat tissue are used as environments. The obtained range of operation appears to be very robust. Measurements show a range of 3 m for the meat case and 2.5 m for a water environment at 868 MHz.

A Tunable Si3N4 Integrated True Time Delay Circuit for Optically-Controlled K-Band Radio Beamformer in Satellite Communication

In this paper we present the design, realization, and experimental characterization of a photonic integrated true time delay circuit on a CMOS-compatible Si3N4 platform. The true time delay circuit consists of an optical side band filter for single side band modulation and an optical ring resonator for broadband time delay. Two methods of optical delay tuning are investigated: 1) optical wavelength and 2) thermo-optic delay tuning. The wavelength controlled tuning enables a large delay tuning range and can be done remotely from a distant location. The close to a linear phase measurements can be used for full beam-scanning of radio signals with frequencies in the 20 GHz band. The thermal control results in a 5 GHz RF delay bandwidth. A proof-of-concept 2 × 1 beamforming is demonstrated in the 20 GHz band. The design presented here can be employed to realize multi-beams for multi-users serviced by multiple satellites.

A Si3N4 PIC for optically controlled 2D radio beamforming in satellite communications

We designed and fabricated a Silicon Nitride (Si3N4) photonic integrated circuit targeting wideband two-dimensional radio beamforming from 20-40 GHz for satellite communications. Continuous true time delay tunability is achieved by using thermo-optic phase shifters in a 2-port optical ring resonator. Scanning angles up to 20° and true time delay bandwidth up to 14 GHz are realized while tuning into the anti-resonance response of the ring resonator. An optical side-band filter using a double-ring loaded Mach-Zehnder interferometer with an FSR of 0.48 nm is designed for a single side band operation. The fabricated photonic integrated circuit is a 4-input / 4-output beamformer for a 2-by-2 focal plane antenna array. It is the first PIC beamformer circuit on Si3N4 designed for operation in the 20-40 GHz band.

Radio beam-steering via tunable Si3N4 optical delays for multi-Gbps K-band satellite communication

We realized a compact Silicon Nitride chip for optically reconfigurable time delays for K-band (17-22 GHz) radio satellite terminals beam-steering. Using 16-QAM 64-OFDM subcarriers we achieved 10 Gbps transmission capacity.

Wide-angle scanning reflector configuration for focal plane arrays

A mathematical analysis of reflector shaping for wide-angle scanning is presented. Parabolic, hyperbolic and spherical reflectors are defined based on geometrical optics method in order to have the smallest deviation of the focused beam (Fig. 1) during wide-angle scanning. It is shown that it is possible to expand the illuminated region of the array by a factor 3 for parabolic reflectors with axial displacement based on an estimated 80 % aperture efficiency at 30 GHz, D/λ=80. Moreover, it is demonstrated that spherical reflector have the smallest deviation from the axis of revolution during wide-angle scanning.

Double-Reflector Configuration for Optimal Exposure of Wideband Focal-Plane Arrays With Optical Beamforming

An optimized double-reflector antenna concept for a wideband focal plane array (FPA) configuration is presented for Ka-band applications with a limited scan range, e.g., ground terminals for satellite communication. The proposed reflector configuration allows maximizing the number of active array elements and minimizing the actual array size during scanning. In addition, the FPA configuration has been optimized for wideband optical true-time-delay beamforming, resulting in wideband operation from 20 to 40 GHz. Based on a minimum required 80% aperture efficiency at 30 GHz, the double-reflector concept allows expanding the illuminated region of the array by a factor of 60 compared to traditional prime-focus configurations. The proposed configuration also decreases the magnification factor M by a factor of 2.5 compared to the double-parabolic configuration for a ±1.5° scan range.

Increasing the EIRP by using FPA-fed reflector antennas

The wireless communication range of E-Band point-to-point antenna systems can be extended by increasing the effective isotropic radiated power (EIRP). By employing a focal plane arrays (FPA), the reflector antenna can generate a high EIRP with electronic beam steering. By axially displacing the FPA towards the reflector, the field pattern across the FPA will be broader. Therefore the number of active elements in the array is increased, resulting in a higher EIRP. An in-house developed FPA model based on the physical optics (PO) surface current method is used in this analysis. It is found that 8 dB can be gained if the FPA with 9 × 9 active array elements is axially displaced by 2.3 λ (Frequency 71 GHz) towards the reflector. For this axial displacement the tapering and spillover efficiency are maximally reduced by 3 %. A higher EIRP can be achieved by increasing the axial displacements, but in this case, the FPA size must be increased in order to meet efficiency criterion of 80 %.