DE546153C - Directional receiver - Google Patents

Description

Today, radio reception technology is extremely capable of high-frequency amplification to achieve high levels of reinforcement. Nevertheless, the results of remote reception today are still unsatisfactory. This is partly due to the fading phenomena, which, however, are already through today automatic volume control can be successfully combated.

However, the main obstacle to long-range reception is the atmospheric disturbance. These on the one hand have a very unfavorable effect on the quality of any long-range reception, on the other hand They limit the range of the receiver by making the waves very distant and weaker Cover the transmitter completely.

In the following, a radio remote receiver is now described which has a very pronounced Has directivity and thereby to eliminate the atmospheric disturbances to a high degree allowed. The schematic circuit diagram shows Fig. 1. As you can see from this already sees, the radio receiver represents a combination of several frame

men receiver, each of which consists of a high frequency amplifier and audio stage. Let us therefore first describe the situation in the case of a simple frame receiver of a known type.

If E denotes the reception strength and the angle φ (azimuth) indicates the direction from which the received wave comes, then the function exists at the frame receiver

E - J sin <p \

(See the curves in Fig. 2, a in polar and b in Cartesian coordinates).

Here one more factor is neglected, the gain of the receiver as well as the field strength of the received Wave depends and which should also be disregarded in the following.

We now consider two separate, completely similar receiving apparatus of a known type, each consisting of a frame (Fig: 1, / J ₁ and /? ₂ ), high-frequency amplifier and audio (Fig. 1, HF ₁ -IA ₁ and HF ₂ - \ - A ₂ ) exist. Both receivers are tuned to the same frequency. The frames of the two receivers are, however, aligned differently so that they form an angle α with one another. The reception strengths E of the two receivers are therefore

E ₁ - j Sin \ φ + j j

E,

sm [φ - - Γ

(Fig. 3> dashed curves).

A common low-frequency amplifier of a known type and a common loudspeaker are now connected to these two receivers (NF - \ - L). This can be done in two ways, either in such a way that the reception strengths E ₁ and E _{2 of} the two receivers add up to one another, or in such a way that they subtract from one another. In this case the

ίο The coupling now takes place in such a way that the reception strengths add up. (The coupling can be done, for example, as shown, by a transformer Tr , which has several primary windings P ₁ , P ₂ ... ) The common reception strength of the two receivers is therefore

=] sin

sin ί 95 - - ^ - j |

(see Fig. 3, solid curve).

A third receiver is now available, which also consists of an HF amplifier and an audio system (see Fig. I, HF ₃ - \ - A ₃ ).

Either a frame R _{3 should be} connected to this receiver or, better still, two separate frames /? ₄ and R ₅ , which are identical and in the same direction as R ₁ and R _{2 described above;} the use of two frames on this receiver has the advantage of being easy to adapt when changing the angle α. Otherwise, these two frames act exactly as one

single frame. In any case it can be achieved, that the reception strength this third receiver of the function follows

sin \ <p - \ 1 + sin I ^

This function is shown in Fig. 4.

It is also possible to use the frame R ₃ or the frame /? ₄ and /? ₅ zuy and instead use the frames " R ₁ and R ₂ , so that only two frames are required in total. In this case, the received oscillations of frames ^ ₁ and R ₂ , as already described, are passed through the audion levels A ₁ and A ₂ are rectified separately, but also fed to the common audio stage A _3. In A ₃ , the reception strength E ₃ results from the above formula.

The final receiver, as shown in Fig. 1, is finally created by the fact that this third audio stage also acts on the common low-frequency amplifier of the first two audio stages, this time in such a way that the reception strength E _{3 is} subtracted from E ₁ , 2. (In the drawing [Fig. 1] this is indicated by the fact that the third primary winding P _{3 of} the transformer Tr is connected in reverse as P ₁ and P _2. ) The dependence of the resulting reception strength of the entire arrangement on the direction angle φ is therefore given by function

sin (9? - -J] | - ^sin

This function is shown in Fig. 5, namely a in polar and b in cartesian Coordinates.

A look at Fig. 5 already shows that the radio receiver described has an extremely strong directivity. No reception at all is recorded from the vast majority of directions, while only those waves are received whose directions of incidence lie within a narrow angle. In terms of its size, this limiting angle is equal to the angle α at which the frames R ₁ and R ₂ intersect, but does not spatially coincide with this, which is particularly clear from Fig. 5a. As you can see, the main receiving direction does not lie in the bisector of the angle α at which the frames cross, but perpendicular to it, i.e. perpendicular to the dash-dotted line of symmetry in Fig. 1.

It can be clearly seen that the receiver described absorbs significantly less interference can be used as an ordinary frame- io <receiver. Incidentally, both the Reception volume as well as the inclusion of disturbances from the size of the anglea away. These relationships are examined quantitatively below. 10;

Since the atmospheric disturbances from all directions of the room scattered on the Receiver hit can be used as a measure of the strength of the recorded atmospheric Disturbances in general the expression in

F = I Edq> apply. This function provides

represents the area shown in Fig. 2 (usual frame receiver) and has been hatched in Fig. 5 (directional receiver according to the present invention).

The main interest is now the dependence of this interference area F on the one hand and the maximum reception strength f _max on the other hand on the angle a at which the

546158

Frame / ^ and R ₂ cross (Fig.i).
Calculation results in the following functions:

the

and

F - const sin -
4th
(Fig. 6, solid curve)

= sin -

(Fig. 6, dashed curve).

For α = 180 ° the situation is exactly the same as for a normal frame receiver. As α becomes smaller, F decreases very quickly, I? _max, on the other hand, is very slow, which can easily be compensated for by increased high-frequency amplification. Here, however, the atmospheric disturbances are also amplified; especially interesting

p
therefore sizes the relative perturbation -. =; ;

fimax

NS.

the result is the function - ^ - = tang-

-fcmax 4

(Fig. 6, dash-dotted curve). This function shows that the relative disturbance

-gi for α = 2o ° only 8.7 o / _o and for α = io °

is only 4.4 o / _{o of} the value it is in the ordinary frame.

In order to avoid mutual coupling between the crossed frames, it can the frames with suitable shields or decoupling devices are necessary to provide.

Claims (1)

Claim: ³ p Directional receiver, characterized in that the high-frequency oscillations of two or more directional antennas at an angle to one another through a Corresponding number of rectifier calls separately rectified and the low frequencies obtained in phase are added, and that the high-frequency oscillations either the same or a corresponding number of other Directional antennas - or the vibrations of a single electrically equivalent Antenna - fed to a single rectifier stage, its low frequency is superimposed in phase opposition on the first-mentioned low frequencies. For this 1 sheet of newspapers