US2297405A - Radio transmitter for obtaining course lines - Google Patents

Description

Sept. 29, 1942. J. GOLDMANN 2,297,405

RADIO TRANSMITTER FOR OBTAINING COURSE LINES Fled March 30, 1940 K n .fm/enfon- Flgf. 4 Jamin QU/mm Patented Sept. 29, 1942 RADIO TRANSMITTER FOR OBTAINING COURSE LINES Joachim Goldmann, Berlin, Germany; vested in the Alien Property Custodian Application March 30, 1940, Serial No. 326,920 In Germany January 19, 1939 (Cl. Z50- 11) 4 Claims.

Radio transmitting arrangements for producing course lines are known by which signals, such as the Morse signals a and n or dots and dashes, are radiated alternately and in a predetermined direction each. In these arrangements exciting or main antennae are constantly fed from a high frequency generator while reflecting antennae are keyed in a manner to produce such signals as directional characteristics.

An arrangement of this kind is described in U. S` Patent 2,028,510 and comprises a vertical dipole, constantly fed from a high frequency generator, and other vertical dipoles spaced by a certain distance therefrom and acting as reflectors. Due to the Vertical position of the dipoles this arrangement operates with vertical polarization. Furthermore, transmitting arrangements for producing course lines are known Which do not use the principle of rellection, in which however horizontal polarization instead of vertical polarization is alforded. This has the advantage that the earth eld will not impair the directive characteristics to such extent as in the case of vertical polarization. This is advantageous especially if the transmitting arrangement is employed for landing aircraft in accordance with the wellknown glide path method.

The present invention aims to employ the principle of horizontal polarization in the case of course line producing transmitting arrangements of the kind using the principle of reflection. According to the invention horizontal antennae or dipoles are employed in lieu of the customary vertical antennae or dipoles.

In the accompanying drawing, Fig. 1 is a diagrammatic elevation showing an embodiment of the invention, Fig. 2 is the radiation diagram to Fig. l, Fig. 3 is a diagrammatic elevation illustrating another constructional form of the invention, Fig. 4 is a plan view showing still another form thereof.

The arrangement represented in Fig. l comprises a horizontal dipole I, a high frequency generator S coupled thereto, and a reflecting dipole 2 or 3 on either side of dipole I. The dipoles 2, 3 are keyed or modulated in well-known manner. The center points of the dipoles I, 2, 3 are spaced apart by the distances between the vertical dipoles of the arrangement described in the aforesaid U. S. patent. Also, for tuning the reecting dipoles the principle disclosed in this Ypatent is employed.

The field intensity diagram here obtained results from the diagrams of the known arrangement, having vertical antennae, and from the d1- rectional diagrams of the horizontal antennae. The directional diagram of the horizontal antennae is a so-called double-circle while the directional diagrams of a radio beacon comprising vertical antennae are cardioids or similar diagrams. The resultant diagrams are represented in Fig. 2 and are designated 4 and 5. The course directions are denoted by 6 and l. At right angles with respect to the directions 6, I there is zero radiation.

In order to prevent in the arrangement according to Fig. l the dipole I from being too intensely coupled to the dipoles 2, 3 the two halves of dipole I may be forked, as shown in Fig, 3, so that the dipoles 2, 3 are located within the forked ends thereof.

In order to avoid in the arrangements represented in Figs. 1 and 3 the zero radiation, which is at right angles to the course direction, and to obtain a radiation effective all around, as is the case with arrangements having vertical antennae, devices of the kind illustrated in Fig. 4 may be adopted. Each of antennae I, 2', 3 here comprises two horizontal dipoles a, b arranged to cross one another. The coupling effective between the dipoles Ia and 2a is equal to that between Ia and 3a. Similarly, the couplings between Ib, 2b on the one hand and Ib, 3b on the other hand equal one another. In a preferred arrangement dipoles a, b of antenna I are continuously fed. To this end, current supplied to dipole Ia is in phase quadrature with that to Ib. Such quadrature current may be provided by known means, designated generally as a phase shifter. It is clear that,

" by virtue of the above-mentioned coupling between the a dipoles of antennae I, 2, and 3 and that between the b dipoles of these antennae, the a elements of antennae 2, 3 may act as reflectors 0f energy radiated from dipole Ia, and 2b, 3b may reflect radiation from Ib. Thus, energy reflected at 2a, 3a may be 90 out of phase with respect to that reected by 2b, 3b, as will be clear. The keying here used is preferably such that either 2a and 2b or 3a and 3b are interrupted simultaneously. In this way either antenna system 2 alone or antenna system 3 will be effective at any one instant.

The mode of operation is such that each of the systems I, 2, 3 produces a radiation which is effective all around and is similar to the radiation characteristic of a vertical dipole. Consequently, the same radiation diagrams result is in the case of vertical dipoles while securing the advantages peculiar to horizontal polarization.

What is claimed is:

1. A radio transmitting arrangement for producing a beacon course line comprising a horizontal dipole arrangement disposed generally transverse to said beacon course line, means for continuously supplying energy to said dipole, reflecting antennae disposed horizontally and one on each side of said dipole substantially in alignment with the longitudinal axis thereof, said reflecting antennae being each substantially equally spaced from said dipole, and means for keying said reilectors to render them alternately effective. Y

2. A radio transmitting arrangement according to claim 1, characterized in that each arm of said horizontal dipole arrangement, which is continuously fed, is generally fork-shaped, the axis of said forks being transverse to said beacon course line, and that said ho-rizontal reflecting antennae are arranged to extend at least partially within said forks.

3. A radio transmitting arrangement according to claim l, comprising a second horizontal dipole arranged substantially in intersecting relation with said dipole, iirst named, means for continuously supplying energy to said second dipole in phase quadrature with respect to that supplied to said dipole, rst named, and additional horizontal reflecting antennae arranged substantially in intersecting relation with said horizontal reilecting antennae, rst named, said second horizontal dipole and said additional horizontal reflecting antennae being disposed substantially perpendicular to said first-named dipole and said first-named reflecting antennae.

4. A transmitting arrangement for producing course lines, comprising a continuously fed antenna, two reectors each arranged on an opposite side of said antenna, means alternately keying each of said vreiiectors, said antenna comprising two horizontal dipoles so arranged as to substantially intersect each other, said reflectors each comprising two horizontal dipoles arranged substantially to intersect each other, and means supplying current to one of said two continuously fed dipoles in phase quadrature with that supplied to the other of said two continuously fed dipoles.

JOACHIM GOLDMANN.

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