Jussi Säily

2-D Beam-Steerable Integrated Lens Antenna System for 5G

The new services available through smart devices require very high cellular network capacity. The capacity requirement is expected to increase exponentially with the forthcoming 5G networks. The only available spectrum for truly wideband communication (>1 GHz) is at millimeter wavelengths. The high free space loss can be overcome by using the directive and beam-steerable antennas. This paper describes a design and the measurement results for a lens antenna system for E-band having 2-D beam-steering capability. Continuous beam-switching range of about ±4° × ±17° is demonstrated with the lens having the maximum measured directivity of 36.7 dB. Link budget calculation for backhaul application using the presented lens antenna system is presented and compared with the measurement results of the implemented demo system.

E

We discuss various possibilities to design phase shifters with reduced frequency dispersion using combined sections of forward-wave and backward-wave transmission lines. It is shown that inclusion of backward-wave sections into a single transmission line always increases the total dispersion. On the other hand, we show that dispersion can be reduced by means of lines with positive anomalous dispersion and provide an example of such line. Furthermore, we report the theory and design of a novel phase shifter, based on parallel combined backward-forward transmission lines. The phase shifts, produced by this device, are characterized with negligible frequency dependence in a wide frequency range. We show that for an ideal performance, phase deviation can be less than 1deg within a 20% bandwidth while excellent impedance matching is retained. We support these theoretical estimates by microwave circuit simulations and direct measurements, showing that the novel phase shifter can be easily implemented with simple electronic components

-Band Access and Backhaul

This paper shows that it is possible to make functional probe-fed patch antennas on low-temperature co-fired ceramic (LTCC) substrates for 60 GHz. The designed antennas were realised on a 0.5-mm-thick LTCC substrate using a commercial Ferro A6-S LTCC material system. According to the measurements, a stacked square two-element patch antenna had 2.7 GHz and a circular single-element patch antenna had up to 6 GHz of the -10-dB-return-loss bandwidth. The manufacturing tolerances caused some de-tuning of the resonance frequency, plusmn1 GHz. The measured maximum radiation gain of the circular antenna was 5.9 dBi at 57 GHz

Artificial lines with exotic dispersion for phase shifters and delay lines

Imaging at submillimetre-wave (SMMW) frequencies is of considerable interest for security applications due to potentially superior performance at longer stand-off ranges in comparison to mm-wave imaging thanks to reduced diffraction. We have demonstrated passive broad-band video rate imaging system operating at a centre frequency of about 600 GHz, capable of 10 frames/second imagery of a 2 m × 1 m field-of-view at a stand-off distance of 5 meters. In addition, a multi-band system centred around 250, 450 and 720 GHz will be discussed. Multi-band imagery is interesting given its potential for rudimentary materials differentiation, a capability that would substantially benefit e.g. security imaging applications. The passive imaging activities are complemented by activities towards developing rapid electronic beam steering capability for imaging submm-wave radars. Results from two projects aiming at constructing such beam steering systems at 120 GHz and at 650 GHz are presented.

Design and Measurements of 60 GHz Probe-fed Patch Antennas on Low-Temperature Co-Fired Ceramic Substrates

Millimetre-wave radio fields are shaped using both amplitude- and phase-type computer-generated holograms (diffractive elements). Methods for hologram element synthesis are described. Holograms that produce plane waves, radio-wave vortices, and Bessel beams at 310 GHz are fabricated and tested.

Towards video rate imaging at submillimetre-waves — Finnish developments of passive multi-band imaging and holographic submm-wave beam steering at VTT

Both active and passive submillimetre-wave stand-off imaging systems are under development for security imaging applications. The drivers for operation at higher frequencies have been the desire for better image resolution, smaller optics package, reduced susceptibility to specular reflections from the human skin and capability for stand-off imagery. In this paper we summarise our efforts on devices, components and systems which could eventually pave the way for fast, real time, high-resolution imaging systems for the submillimetre-wave range.

Radio-wave beam shaping using holograms

A novel dual-polarized microstrip patch antenna is presented. The antenna uses proximity-coupled microstrip feed lines along the patch corners and covers the full WCDMA/UMTS band with only a single radiating patch. The corner-fed patch arrangement results in two orthogonal linear polarizations along the patch diagonals with high isolation. The presented antenna can be applied in dual-slant polarized base station antenna arrays. The measured input matching of both ports at TX&RX bands of 1920-1980 MHz and 2110-2170 MHz is below -13.8 dB and the polarization isolation is more than 30 dB. Measured gain is about 10 dBi, and half-power beamwidths in the horizontal plane about 45deg -55deg . Cross-polarization is better than -22.5 dB.

Developments towards real-time active and passive submillimetre-wave imaging for security applications

Computer-generated holograms can be used for shaping millimeter-wave beams. The radio holograms used are either amplitude or phase holograms. An amplitude hologram has been proven to be a feasible alternative as a focusing element in a compact antenna test range (CATR) in the mm-wavelength regime. Holograms in other mm- and submm-applications are also studied - especially for the creation of nondiffracting Bessel radio beams.

Proximity-coupled and dual-polarized microstrip patch antenna for WCDMA base station arrays

In this paper we present imaging results obtained from frequency modulated continuous wave radar setup operated at 650 GHz and optimized for imaging of objects with lateral dimensions between 1-20 cm. We consider in particular the ability and the benefits of using such system for resolving features corresponding to depth variations smaller than the standard depth resolution of FMCW systems. This is accomplished by observing the lateral variation of the amplitude and the phase of the reflection coefficient within one range bin. The presented imaging results from 3D printed plastic phantom objects resolve features with depth profiles down to 0.1 mm in the system with a range bin of 5 mm.

Experimental studies on radio holograms at mm- and submm-wavelengths

We report an advanced phase compensation principle, which employs combined backward-forward transmission lines having similar frequency dispersion. Various applications of this principle to the design of microwave devices allow for an exceptionally low dispersion in a wide frequency range while keeping the structure very compact and simple compared to conventional solutions.