US3382464A

US3382464A - Undirectional coaxial line device comprising a semiconductor body and a lossy body

Info

Publication number: US3382464A
Application number: US427308A
Authority: US
Inventors: Gremillet Jacques
Original assignee: CSF Compagnie Generale de Telegraphie sans Fil SA
Current assignee: Thales SA
Priority date: 1964-01-23
Filing date: 1965-01-22
Publication date: 1968-05-07
Anticipated expiration: 1985-05-07
Also published as: GB1101642A; FR1392566A; DE1261913B; NL6500762A

Description

'7, 168 J. GREMILLET 3,332,464 UNIDIRECTIONAL COAXIAL LINE DEVICE COMPRISING A SEMICONDUCTOR BODY AND A LOSSY BODY Filed Jan. 22, 1965 m M w w United States Patent Oflice 3,382,464 Patented May 7, 1968 3,382,464 UNDIRECTIONAL COAXIAL LINE DEVICE COM- PRISING A SEMICONDUCTOR BODY AND A LOSSY BODY Jacques Gremillet, Paris, France, assignor to CSF-Compagnie Generale de Telegraphic Sans Fil, a corporation of France Filed Jan. 22, 1965, Ser. No. 427,308 Claims priority, appligztitirzl rance, Jan. 23, 1964,

3 Claims. (61. 333-24 ABSTRACT OF THE DISCLOSURE The present invention relates to coaxial lines and more particularly to the propagation of circularly polarized Waves through such lines. 1

This invention provides a unidirectional line of the above type wherein a semi-conductor body is placed at the surface of separation of said layers, an energy dissipating body being mounted on the same surface diametrically opposite with respect to the semi-conductor.

For a better understanding of the invention reference will be made to the drawing accompanying the following description and in which:

FIG. 1 shows in cross section a coaxial line according to the invention, and

FIGS. 2 and 3 show in cross section coaxial unidirectional lines according to thelinvention. 1

The coaxial line shown in FIG. 1 comprises a central conductor 1 of a metal having a good conductivity and an outer conductor 2. Conductor 1 is surrounded by a concentric dielectric layer 3, which is in turn surrounded by another dielectric layer 4, with a different dielectric constant. Layer 3 is, for example, a ceramic such as magnesium titanate, and layer 4, is for example, air and fills the space between layer 3 "and the outer sleeve 2. The electromagnetic energy is applied to such a coaxial line through any suitable matching device, such as, for example, those used in the conventional stub techniques.

It is known from the US. Patent No. 3,078,425' that, by suitably selecting the respective dielectric constants and the thickness of

layers

3 and 4, a substantially circular polarization of the propagated wave is obtained near the cylindrical

surface separating ltyers

3 and 4 in a plane perpendicular to that of the FIG. 1.

An equivalent result can also be secured by covering the inside of the sleeve 2 with ceramic, the air layer being then located round the inner core 1, or by substituting for air another suitable dielectric.

Turning now to FIGS. 2 and 3, it is known that, in the presence of a constant transverse magnetic field in the line, a semi-conductor behaves, for an electromagnetic wave whose electrical polarization is substantially circular, as a dielectric, the dielectric constant of which depends on the direction of polarization of the wave. This effect is known as the Helicon effect."

In FIGS. 2 and 3 a semi-conducting plate 5, having a length of the order of M2, A being the operating wave length, in the semiconductor body for example of indium antimonide and an energy dissipating body, such as for example a graphite bar 6, have been added. These two elements of the isolator are diametrically opposite one another on the surface of the ceramic layer 3.

This surface attachment corresponds to the case where the circular polarization of the metric wave which propagates along the line, is obtained in the air layer 4 and near the surface of ceramic 3.

Should the circular polarization be obtained near the

surface separating layers

3 and 4 but within the ceramic, the semi-conductor body and the graphite bar would have to be sunk in the ceramic layer 3.

FIG. 2 corresponds to one direction of circular polarization and FIG. 3 to the opposite direction of this polarization, the magnetic; induction ,3 being assumed to be in the same direction in both cases.

The dotted line 7V in FIGS. 2 and 3 is intended to designate in a schematic form the electromagnetic energy concentration in one region or another oft he coaxial line, according to the direction of the polarization, and hence to the direction of wave propagation.

In the case of FIG. 2 the whole of the energy is concentrated at that side of conductor 1 where body 5 is positioned, the reverse being true with respect to FIG. 3. This may be briefly explained as follows:

In FIG. 2, in accordance with the Helicon effect as related to the shown direction of the DC. magnetic induction, the equivalent dielectric constant of semi-conductor 5 has a high positivevalue, so that the energy is concentrated in a region 7 surrounding the semi-conductor 5 and not including the graphite bar 6.

Under these conditions, the electrical wave energy propagates through the coaxial line with no appreciable loss.

On the contrary, in FIG. 3, since the direction of polarization is the reverse of the preceding one, the equivalent dielectric constant of semi-conductor 5 has a high negative value due to the Helicon effect, so that the energy is no longer concentrated in the vicinity of the semi-conductor body 5, but in the vicinity of the graphite.

Since the latter is the seat of large losses, a wave polarized in said defined direction is not transmitted, or is badly transmitted, beyond the line portion according to the invention.

Of course the invention is not limited to the embodiment shown which was given solely by way of example.

What is claimed is:

1. A coaxial line for ultra high frequency waves comprising an inner conductor; an outer conductor surrounding said inner conductor, and spaced therefrom; a first dielectric layer surrounding said inner conductor and a second dielectric layer filling up the space between said first layer and said second conductor, said layers having different dielectric constants, means for creating within said line a constant magnetic field having a predetermined direction; a semi-conductor body fixed to said first layer; and an energy dissipative body fixed to said first layer diametrically With respect to said first body.

2. A coaxial line for ultra high frequency waves comprising an inner conductor surrounding said inner conductor, and spaced therefrom; a first dielectric layer surrounding said inner conductor and a second dielectric layer filling up the space between said first layer and said second conductor, said layers having different dielectric constants; means for creating within said line a constant magnetic field having a predetermined direction; a semi-conductor-body fixed to said first layer; and a graphite body fixed to said first layer diametrically with respect to said first body. r r i a 3. A coaxial line for ultra high frequencywaves comprising an inner conductor; an outer conductorsurrounding said inner conductor, and spaced therefrom, a first magnesium titanate layer surrounding said inner conductor and a second dielectric layer filling up the space between said first magncsiurntitanate layer and said conductor, said layers having different dielectric constants; means for creating with in said line a constant magnetic field having a predetermined direction; an indium antirnonide body fixed to said first layer, and a graphite body fixed to said first layer diametrically with respect to said first body.

Refererfc es Cited UNITED STATES PATENTS 4/1957 Raisbeck. 7/1960 Crowe 3338 OTHER REFERENCES Barlow, Microwave Hall Effect and the Accompanying Rotation of the Plane of Polarization, Proc. of the IEE, February 1961,'pp. 349353.

Moreno, Microwave Transmission Design Date, Dover Publications, N.Y., 1948, pp. 82-83, relied on.

HERMAN KARL SAALBACH, Primary Examiner. PAUL GENSLER, Examiner.