A method for ice thickness characterization using GNSS C/N0 data

Abstract A Dual Circular Polarized (CP) reception method is proposed to simultaneously record direct and reflected signals in GNSS reflectometry. The purpose of using a dual CP antenna system is to exploit incident wave’s polarization variation after reflection. This paper presents the theoretical background for dual CP reception system and the advantage of using dual CP system over a single polarization. Theoretical multipath propagation is validated by measurements performed at frozen Baltic sea. The Right-Hand Circular Polarization (RHCP) and Left-Hand Circular Polarization (LHCP) received signals are post-processed to retrieve information about the measurement environment. The analysis method gives the evidence of penetration of GNSS signal into the layered media and the possibility to characterize ice-thickness or layered media using only C/N0 data

A 14.6 GHz–19.2 GHz digitally controlled injection locked frequency doubler in 45 nm SOI CMOS

Abstract In this paper we present a wide locking range (14.6 GHz–19.2 GHz and 12.65 GHz–20.6 GHz, -3 db and -6 dB, respectively) injection locked frequency doubler implemented with 45 nm CMOS SOI technology. The doubler is designed and optimized for a 5G sliding-IF transceiver architecture. It exploits a digitally tunable LC tank to enhance the frequency range. Measured results show 36–55 dBc fundamental and 40–54 dBc 3rd harmonic suppression as well as 10 dB peak conversion gain. Phase noise performance of the doubler has also been measured. The power consumption varies from 5 mW to 11 mW. The core size is 270 µm x 450 µm

Analysis of vertical loop antenna and its wide and flat variant performance in wearable use

Abstract This paper presents an analysis of the input impedance and radiation pattern behavior for a rectangular loop antenna when it is reshaped from a narrow square to wide and flat. The antenna operation is examined by 3D electromagnetic simulations. Parametric simulation results are shown to explain the effect of antenna dimensions on the impedance behavior. Based on the numerical results, an equivalent circuit is developed to model the impedance change due to reshaping the loop antenna. The main observations are that the decreased height and the increased width of the antenna increase the bandwidth potential of the inherently narrowband loop and increase its directivity. These characteristics together with a vertical loop orientation enable a high performance antenna for locations very close to conductive or lossy materials. Based on the presented impedance analysis, an optimized antenna prototype for a wearable use is manufactured and its performance is verified by measurements. Measured radiation efficiency for the antenna in contact with a human tissue phantom is -5.0 dB at 2 GHz and the obtainable bandwidth potential is > 10 %

Design of a 40 GHz low noise amplifier using multigate technique for cascode devices

Abstract Increased parasitic components in silicon-based nanometer (nm) scale active devices have various performance trade-offs between optimizing the key parameters, for example, maximum frequency of oscillation (𝑓𝑚𝑎𝑥, gate resistance and capacitance, etc. A common-source cascode device is commonly used in amplifier designs at RF/millimeter-wave (mmWave) frequencies. In addition to intrinsic parasitic components, extrinsic components due to wiring and layout effects, are also critical for performance and accurate modelling of the devices. In this work, a comparison of two different layout techniques for cascode devices is presented to optimize the extrinsic parasitic elements, such as gate resistance. A multi-gate or multi-port layout technique is proposed for optimizing the gate resistance (𝑟𝑔). Extracted values from measurement results show reduction of 10% in 𝑟𝑔 of multi-gate layout technique compared to a conventional gate-above-device layout for cascode devices. However, conventional layout exhibits smaller gate-to-source and gate-to-drain capacitances which leads to better performance in terms of speed, i.e. 𝑓𝑚𝑎𝑥. An LNA is designed at 40 GHz frequency using proposed multi-gate cascode device. LNA achieves a measured peak gain of 10.2 dB and noise figure of 4.2 dB at 40 GHz. All the structures are designed and fabricated using 45 nm CMOS silicon on insulator (SOI) technology

Analyzing 5G RF system performance and relation to link budget for directive MIMO

Abstract Wideband fifth generation (5G) systems utilizing high carrier frequency and multiple-input multiple-output (MIMO) raise major challenges for the system design. Wave propagation and practical hardware tradeoffs at higher frequency ranges provide new boundary conditions for the implementation. This paper addresses system performance boundaries and the analysis method towards multibeam communications at mmW. We combine analysis from antennas and propagation to the RF transceiver specifications and beamforming requirements. Realistic propagation model and antenna implementation is used to generate beam-specific path gains and provide a wide variety of user scenarios. Using this approach, system level interdependencies and RF performance boundaries can be verified with different antenna configurations in various propagation environments. As an example, we present MIMO link budget analysis targeting 10 Gbits/s for multiple devices in the office scenario at 27 GHz

Millimeter-wave frequency reconfigurable low noise amplifiers for 5G

Abstract In this brief, designs of two millimeter wave (mmWave) reconfigurable multi band low noise amplifiers (LNA) are presented targeted for fifth generation (5G) communications. A reconfigurable tunable load based on electrical and magnetic tuning is proposed to cover three mmWave frequency bands for 5G, i.e. 24 GHz, 28 GHz and 39 GHz. Two LNA structures are designed and fabricated using 45nm CMOS SOI technology. The first toplogy (LNA1) is composed of a single input wideband matching circuit to cover frequency operations from 24 GHz to 40 GHz. On the other hand, second topology (LNA2) uses three separate narrowband match inputs, one for each frequency band, with combined output. Design methodology of passive and active devices is presented towards compact integration of LNAs for systems such as, phased arrays. Ground plane and its impact on the performance parameters is also discussed in this work. Measurement results show a wideband noise figure (NF) ranging from 3.8 dB to 4.9 dB and gain of 8.5 dB to 12.5 dB for LNA1 at different bands. Similarly, LNA2 exhibits NF of 4.5 dB to 5.5 dB and gain of 9.5 dB to 15.5 dB across all bands. Total area (including pads) of LNA1 and LNA2 are 0.316 mm2 and 0.695 mm2, respectively

Depolarization due to wedge diffraction in satellite radiowave communication

Abstract In this paper, the depolarization effect due to the electromagnetic wave diffraction from the rooftop wedge of a building at 1.575 GHz frequency is presented. Diffraction measurement was performed using a dual circularly polarized (CP) antenna system. The Right Hand Circularly Polarized (RHCP) Global Positioning System (GPS) satellite transmission was utilized for measurement. The orbital motion of a single satellite enabled diffraction measurement as a function of the receiver depth in the shadow region, while the receiver was static. The experimental result of RHCP signal was compared with a theoretical knife-edge diffraction model, and they were in good agreement. In case of the deep shadow region, we found the levels of left- and right circular polarized signals to be equal, which indicates a strong depolarization of the incident RHCP wave. The observed depolarization for conductive wedge is explained by the geometrical theory of diffraction

Inter-beam interference reduction in hybrid mmW beamforming transceivers

Abstract Practical radio frequency beamforming can suffer from high sidelobe levels which cause inter-beam interference (IBI) in multibeam transceivers. IBI can be reduced by shaping the amplitude and phase excitation over the individual antenna elements. However, such methods do not exploit the available power efficiently in practical arrays, where each antenna is driven with a dedicated power amplifier. In this paper, we show a simplified approach for hybrid beam synthesis in subarray-based beamforming architecture and propose a two-stage beamforming method for cancelling the IBI. The proposed technique cancels the interference between the subarrays while it maximizes the effective isotropic radiated powers in the desired directions. Simulation show typically over 40 dB IBI rejection for randomly spread beams and more than 4 dB improvement for radiated power compared to amplitude tapering

Statistical measurement system analysis of over-the-air measurements of antenna array at 28 GHz

Abstract Next generation communication systems will use millimeter wave communication to enable higher data rates compared to Long Term Evolution (LTE) system. The coming 5G system will use antennas antenna arrays and multiple radio transceivers to compensate an excess radio signal path loss and conductive testing of an antenna array will be a challenge. Over-the-air (OTA) testing provides solution to cabling and connection problems. This paper provides an analysis of accuracy of OTA measurement at 28 GHz frequency band. A statistical measurement system analysis is used and results show that ± 0.89 dB measurement accuracy is achieved in a typical laboratory environment without an anechoic RF chamber

A coherent spurious analysis for sub-THz frequency multiplier chains

Abstract At sub-THz frequencies, the local oscillation for transceivers is often generated by an analog frequency multiplier tree. This paper studies the origins and minimization of spurious tones in a local oscillator multiplier consisting of a chain of frequency doublers. It is found that the nearest spurious components depend on the leakage of the input signal in the first multiplier, which can be minimized by active bias tuning, filtering in the first stage or better balance in the driving differential signal. To verify the nonlinearity modeling, 0.13-μm SiGe BiCMOS technology has been utilized