Millimetric Wave Frequency Devices
- Date:
- March 29, 2005
- Source:
- Elhuyar Fundazioa
- Summary:
- A telecommunications engineer at the Public University of Navarre has designed and developed new millimetric wave frequency receptors using Electromagnetic BandGap (EBG) technology.
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For his PhD thesis, Iñigo Ederra Urzainqui, a telecommunications engineer at the Public University of Navarre, designed and developed new millimetric wave frequency receptors using Electromagnetic BandGap (EBG) technology. These new devices, designed and optimised through his research, signify an advance on the present state of technology given that, previously, this type of configurations had not been used in ant real system.
What is involved here is a kind of technology that can be used in image formation systems, working with millimetric wave frequencies. Instruments which work with this technology are, for example, digital photographic cameras that function at frequency ranges other than the visible. In this way, given the particular properties of the materials at this range of frequencies, these kinds of devices can have applications in fields such as radio astronomy or systems of security as, at these frequencies”. Other fields in which this type of technology can be used is medicine, given that the response from a healthy tissue is distinct from that of an unhealthy one, or vision systems in low visibility conditions where signal weakening due to mist or fog is less with range of frequencies than with the visible one.
The PhD falls within the framework of the research project being undertaken with the collaboration of the Rutherford Appleton Laboratory in England, the University of Eindhoven in Holland and the European Space Agency. The work is entitled, “Electromagnetic BandGap Technology for Millimetre Wave Applications”. Prior to its presentation, the PhD thesis had been awarded by the EPSON-IBÉRICA Foundation with their Rosina Ribalta Prize for 2004 for the best doctoral thesis in the field of Information and Communications Technologies (ICT).
Creation of images at millimetric wave frequencies
An “imaging array” is a cluster of detectors by means of which an image is formed. The functioning of the eye or of a digital camera will be similar to these kinds of devices, the main difference being the operating wave frequency used: the first two both function at visible wave frequencies while our device the range of working wave frequencies is about 500 GHz.
For this PhD, EBG structures for applications in millimetric and submillimetric wavebands (frequencies of between 30 GHz y 3 THz) were investigated. This technology can be used for the design of receptors which can be used as “pixels” in a camera working at millimetric wave frequencies. In particular, the study has targeted the optimisation of the operation of detectors using EBG technology.
Configuration of aerials
The PhD is in two parts. In the first, the basic properties of aerial configurations were studied using EBG structures as substrates. To this end, two EBG structures were considered: the “woodpile” and the Fan structure.
For each one of these structures, the behaviour of a flat aerial installed thereon was characterised, investigating both the radiation characteristics and its entrance impedance. The results showed that it is difficult to find a dipolar configuration for the “woodpile” that simultaneously presents good radiation and adaptation characteristics. To solve this problem, a modification of this EBG structure was proposed, one easy to implement given that it is based on the displacement of the bars in the upper level of the “woodpile”.
Design of the two receptors
The second part of the PhD consisted of the design of two types of receptors that included combinations of flat aerials and EBG materials as radiant elements. These receptors function as direct detector and subharmonic mixer. In the case of the direct detector, the design was optimised in order to achieve the maximum sensitivity of 500 GHz. As regards the subharmonic mixer, it was designed to minimise the noise temperature, in this case working with a wave frequency of 250 GHz. In both cases the results obtained coincided with those predicted. Thus, we can say that the results are very promising and bear out the validity of EBG technology for these kinds of applications.
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