摘要:

Heat is generated in a variety of dielectric or electrical insulating materials when subjected to radio and microwave frequencies. This phenomenon has been successfully exploited for over 40 years by industry in a wide range of applications. Radio frequency (RF) is used for about 90% of all dielectric heating applications, but the more recent development of microwave heating is becoming well established. The place of RF and microwaves in the electromagnetic spectrum and the effects of different frequencies on materials is discussed. Brief details of the various techniques of applying the RF or microwave energy to materials are given. Finally, some typical applications such as welding, baking drying and preheating are discussed.

DOI:10.1049/ip-a-1.1981.0088

出版商:IEE    

年代:1981

数据来源: IET

摘要:

The paper summarises the exposure limits that have been promulgated by national organisations of different countries, and the rationales that have been advanced for establishing these limits. The limits differ by orders of magnitude, largely because of different philosophical approaches to standard making. The limits were developed, in the first instance, because of concern about high-power radar equipment, but have gradually been extended to cover very much lower frequencies. New standards are being developed in the USA which are much more restrictive as regards RF exposure. The justification for these is examined.

DOI:10.1049/ip-a-1.1981.0089

出版商:IEE    

年代:1981

数据来源: IET

摘要:

There is great interest in the use of heat, either alone or together with radiotherapy or chemotherapy, to treat cancer patients. In the paper, some of the physical techniques for heating tissues are discussed. These methods involve capacitive, inductive or radiative transfer of electromagnetic power to the tissue. Following a brief description of the interaction between tissues and electromagnetic fields in the spectral range 100 kHz–10 GHz, the advantages and\or disadvantages of each method are outlined. Throughout, emphasis is on clinical application.

DOI:10.1049/ip-a-1.1981.0090

出版商:IEE    

年代:1981

数据来源: IET

摘要:

The factors determining the interaction with biological material of radiowaves and microwaves at the macroscopic, cellular and molecular levels are briefly discussed in terms of the relevant physical parameters for electromagnetic radiation in the frequency range 10 MHz–300GHz. This is followed by a summary of the results of the reported animal andin vitroexperiments, and it is concluded that, with the possible exception of a few cases awaiting further investigation, the biological effects of radiowaves and microwaves at these frequencies have a thermal basis for their explanation. The implication for human exposure of what is known in respect of fundamental mechanisms of interaction and the results of animal experiments are discussed, and it is explained why the present exposure limit of 10mW\cm2requires modification at the lower end of this frequency range.

DOI:10.1049/ip-a-1.1981.0091

出版商:IEE    

年代:1981

数据来源: IET

摘要:

A review is presented of the studies associated with radio-frequency ignition hazards which have been undertaken since the production of the first British Standard (BS 4992) on this subject in 1974. Initially a brief review is given of the major assumptions used in this standard and its draft revision of 1976 and, then, the research and tests carried out between 1977 and 1981 are discussed in detail. Finally the prime findings relevance to the production of a new standard summarised.

DOI:10.1049/ip-a-1.1981.0092

出版商:IEE    

年代:1981

数据来源: IET

摘要:

A radiation hazard perhaps not generally given sufficient attention is that of one high-power radar burning out the receiver of a nearby system as a result of power coupling via their aerials. A review of various receiver peak-power withstands reveals that pulse power of 0dBW is a suitable working figure for such studies, although individual devices exhibit a fairly wide range of withstand levels. Design curves have been derived to allow rapid assessment of the risk of receiver damage.

DOI:10.1049/ip-a-1.1981.0093

出版商:IEE    

年代:1981

数据来源: IET