the hf cable illustrated in the fig1 and 2 has a tightly packed dielectric which can be in form of a solid or a foam . the cable has an inner conductor 1 , a dielectric 2 and a tubular outer conductor 3 applied concentrically over the inner conductor 1 . a jacket 4 made , for example , of polyethylene can be placed over the outer conductor 3 . the jacket 4 can also be made of a flame - retardant halogen - free material . the inner conductor 1 and the outer conductor 3 are preferably made of copper . the inner conductor 1 can be in the form of a smooth or a corrugated tube or can be in solid form . the outer conductor 3 can be a smooth tube , but can also be corrugated . according to fig1 and 2 , the dielectric 2 fills the entire space between the inner conductor 1 and the outer conductor 3 and acts as a spacer between the two conductors 1 and 3 . the outer conductor 3 consequently makes contact with the dielectric 2 which is a two - component material composed of a thermoplastic insulating material and a mineral material . the mineral material is added to the thermoplastic insulating material in the form of a large number of particles . the particles are added to thermoplastic insulating material in a pre - manufacturing step and distributed as homogeneously as possible . the two - component material thus formed can be extruded onto the inner conductor 1 when the hf cable is manufactured . the hf cable can also be constructed with a hollow dielectric as illustrated in the fig3 to 6 . as illustrated in fig3 the spacers for the two conductors 1 and 3 are here in the form of disks 5 which are spaced - apart axially and contact both conductors 1 and 3 . the disks 5 can be extruded onto the inner conductor 1 in a similar fashion as described with reference to fig1 . the disks 5 can also be prefabricated and pushed onto the inner conductor 1 . the spacer of the hf cable of fig4 is a helix 6 . the helix 6 is prefabricated from the two - component material and is wound onto the inner conductor 1 . the mineral material can also be concentrically applied to an hf cable , leaving the design of the cable unchanged . for example , with an hf cable with a hollow dielectric according to fig5 additional disks 8 made of a mineral material can be placed between two spacer disks 7 made of a thermoplastic material . the disks 8 can be spaced farther apart than the disks 7 , because the disks 8 are used only to keep the hf cable operational when the disks 7 can no longer perform their function . this can happen , for example , in the event of a fire or if high temperatures occur for other reasons . consequently , the disks 8 do not have to contact the outer conductor 3 , at least not in a supporting function , when the hf cable is transported or installed and during normal operation . for this reason , the disks 8 can have a significantly smaller diameter than the disks 7 . preferably , the disks 8 contain very little material . disks made of a mineral material can also be employed with an hf cable where the spacer is a helix 9 , as is illustrated , for example , in fig6 . the helix 9 has a continuous cordage 10 contacting the inner conductor 1 which is corrugated in the transverse direction . spaced apart supports 11 protrude outwardly from the cordage 10 , with the free ends of the supports 11 contacting the outer conductor 3 which is also corrugated in the transverse direction . the disks 14 made of mineral material as shown in fig6 can be arranged in the regions between the supports 11 . these disks 14 have cut - outs for receiving the cordage 10 of the helix 9 . this embodiment likewise does not require that the mineral disks 14 provide support . according to fig7 the hf cable can also be provided with a tightly packed dielectric made of a thermoplastic material , either in solid form or in the form of foam . disks 12 made of mineral material and separated from each other axially by a relatively large distance are arranged between the inner conductor 1 and the outer conductor 3 . the disks 12 are constructed in the same manner as the disks 8 of fig5 . the construction of the spacers from thermoplastic insulating material on the one hand and from mineral material on the other hand also applies when individual supports are installed . the thermoplastic insulating material used in all embodiments can be made , for example , of polyethylene or polypropylene . the mineral material can be ceramic or glass . the outer conductor 3 is commonly applied over the dielectric after the dielectric is formed . the entire hf cable can be manufactured in a single operation . if desired , the jacket 4 can be applied in the same operation . the hf cable of the construction described above is fully functional under normal operating conditions . the thermoplastic material melts at high temperatures , particularly in the event of a fire . however , the mineral particles contained in the thermoplastic material do not melt . they retain their function as spacers and prevent contact between the inner conductor 1 and the outer conductor 3 . the hf cable therefore continues to function — albeit in a limited capacity . the embodiments described above admirably achieve the objects of the invention . however , it will be appreciated that departures can be made by those skilled in the art without departing from the spirit and scope of the invention which is limited only by the following claims .