The millimetre wave (MMW) frequency region is of more and more interest for wide band telecommunication and imaging systems, material spectroscopy, medical treatments, collision avoidance radars and other appli­ cations (Fig.l .1). In spite of the problems in technology, higher price of basic components (in comparison with those at microwaves) MMW meet expanding interest of consumers, and are considered as the most challenging communi­ cation service of the current decade [1]. MMW imaging is not troubled with opaque obscurants such as smoke, fog, and atmospheric drops, therefore it has significant advantages over optical and infrared [2]. Certain spectrum peculi­ arities of electromagnetic wave propagation can be used for confidentiality of wireless telecommunication systems and provide multipoint interactive video service, indoor communications and wireless access to local area networks [3].

1. Telecommunications: Wide-Band, Portable, Confidential