R. Camblor

Microwave Frequency Tripler Based on a Microstrip Gap with Graphene

In this work, a 3x frequency multiplier implemented with a microstrip gap covered with defoiled graphene is presented. The behaviour of the multiplier has been experimentally characterized for the input signal frequency band between 2.5 GHz and 5 GHz. Several graphene-based tripler devices have been implemented with different values for the line width and gap of the microstrip line in order to evaluate the influence of these parameters on the power of the output signal. The output power of the different devices has been measured in the band from 7.5 GHz to 15 GHz for different values of the input power. An almost flat frequency behaviour for the output power is observed along the whole input frequency band.

Submillimeter-Wave Frequency Scanning System for Imaging Applications

A new submillimeter-wave imaging system based on the frequency scanning concept is presented. Using significantly less information than beam-steering techniques, frequency scanning-based imaging systems are able to provide angular information in range-based radar systems which do not allow mechanical or electronic beam steering. Several strategies have been adopted to overcome the low dynamic range due to the propagation losses and non-specular reflection on the object-under-test. Moreover, the system is not only capable of detecting the placement of the objects, but also their profile. In this sense, an imaging application showing the system capabilities for the detection of objects concealed under clothes is presented. Results using 1-D FSAA allowing profile imaging are shown, proving the validity of the proposed system.

A novel phaseless frequency scanning based on indirect holography

A phase retrieval technique for multifrequency scattered field acquisition is presented in this paper. The proposed setup is based on indirect holography schemes so that it combines the desired signal with a known reference signal. The setup is used together with a two-dimensional frequency scanning (FS) antenna and, therefore, the positions of scatterers can be retrieved without the need of moving either the antenna or the objects.

Frequency Scanning Array Composed of Antipodal Linearly Tapered Slot Antennas

In this work, a frequency scanning array of antipodal linearly tapered slot antennas is presented. The system is capable of performing beam steering from –11 to 10 degrees while sweeping the frequency from 8.25 GHz to 11.5 GHz. The beam scanning is achieved by means of a specially designed feeding network that divides the power and introduces the proper phase shift for each antenna port in the frequency range of interest. Experimental results showing the full array behaviour are also presented.

Frequency scanning slotted waveguide in the sub-millimeter wave band

In this work, a waveguide slotted antenna array working in the sub-millimeter wave band is presented. The antenna performs beam tilting from 68 to 89 degrees in the H-plane while sweeping the frequency from 240 GHz to 310 GHz. Sixteen rectangular slots have been cut in the wide surface of a standard WR-3 brass metal rectangular waveguide to obtain the desired behavior. The antenna has been fabricated combining laser and mechanical prototyping machinery. Experimental results showing the main waveguide slotted antenna array characteristics are also presented.

Design of a submillimeter microstrip array for beam-scanning applications

A microstrip array antenna with beam-steering capabilities is presented for imaging applications working in the frequency range of 240–279 GHz. A 33 degrees beam-scanning range is achieved. The feeding network allows to change the beam-pointing angle from θ= −8° to θ= 25° while the frequency scanning is performed.

Millimetre wave textile integrated waveguide beamforming antenna for radar applications

In this work, a fully Textile Integrated Waveguide (TIW) beamforming antenna for its use in a radar system operating at 77 GHz is presented. The TIW beamforming antenna is based on a Substrate Integrated Waveguide (SIW) slot antenna array and it is designed to be manufactured completely with conductive and non-conductive threads using industrial textile machinery, avoiding subsequent sewing and adhesive processes for its integration in wearable or comformable systems. The antenna performs beam tilting from 11 to 23 degrees in the H-plane while sweeping the frequency from 70 GHz to 77 GHz. Firstly, a design of the equivalent SIW beamforming antenna structure is simulated and optimized and then, the translation into a fully woven TIW beamforming antenna structure is presented. The proposed TIW beamforming antenna design is provided with a TIW to WR10 standard rectangular waveguide transition for its experimental validation.

Antenna Manufacturing at VHF Frequencies Applied to Weather-Satellite Data Reception [Education Column]

The aim of this paper is the description of experience in teaching a university extension course for manufacturing homemade antennas and receiving weather-satellite images with them. We thus introduce students to the field of antennas with a very entertaining application example that they can easily reproduce by themselves. The different topics covered by the course are described, with a special emphasis on the description of the antennas and how they are manufactured, which are the core topics of the course. Antenna reflection parameters and received weather images are shown to illustrate the good results achieved by the students.

Analysis of the Locking Range of Rationally Synchronized Oscillators With High Reference Signal Power

In this paper an in-depth study of the behavior of rationally synchronized oscillators (RSO) is presented. The circuit is optimized in order to achieve a broad synchronization bandwidth with low reference signal power through the selection of the adequate harmonic content. The nonlinear dynamics of the RSO is analyzed, focusing on the different bifurcation points which delimit the locking range when high reference signal power is considered. An RSO prototype with rational synchronization ratio r=3/5, autonomous frequency fo=3 GHz and reference signal frequency fr=5 GHz has been manufactured and experimentally characterized, demonstrating a good agreement with simulation results.

Millimetre wave imaging system for the detection of hidden elements in artwork

In this work, a millimetre/sub-millimetre wave imaging system for the analysis, characterisation and detection of hidden elements in artwork is presented. The practical implementation of the system relies on a novel generation of purpose developed frequency multiplier and mixer topologies, based on graphene non-linear devices. The proposed set-up will be experimentally validated by scanning a model painting, in order to practically illustrate the imaging capabilities of the system.