DD139680A3 - ANTENNA FOR SEVERAL RECEPTION AREAS WITH ELECTRONIC AMPLIFIERS - Google Patents

Abstract

The invention relates to an antenna for several Reception areas with electronic amplifiers, which take the form of a Dipole or monopole and in a lower and an upper Frequency range receives, where the length of the dipole or monopole very short of the wavelength of the lower frequency range is. The aim of the present invention is to increase the sensitivity electronic antennas, for example, in the LMK and VHF range received, compared to electronic antennas after the ,, Two way principle * 'ira lower frequency range to improve. The Task is solved in that the capacitive load on Input of the amplifier for the LMK range by splitting the Signals of the upper and lower frequency range to separate Amplification paths ara output of the first electronic Amplifier element is reduced, wherein a common Amplification of both frequency ranges in the first electronic Amplifier element is avoided. The inventive electronic antenna is for example as an electronic car antenna, as an electronic antenna for travel and home receivers and for other purposes of reception in an upper and lower Frequency range applicable.

Description

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a) Title of the invention *

Antenna for several reception areas with electronic amplifier

b) Field of application of the invention

The invention relates to an antenna for multiple reception areas with electronic amplifier, which has the form of a dipole'oder'monopol and receives in a lower and an upper frequency range ', wherein the length of the dipole or monopole is very short compared to the wavelength of the lower frequency range. The electronic antenna according to the invention is applicable, for example, as an electronic car antenna, as an electronic antenna for home and travel receivers and for other receiving purposes in an upper and lower frequency range,

c) Characteristic of the known technical solutions

For the reception of the amplitude-modulated broadcasting in the long, medium, short wave range (LMK range) and the frequency-modulated broadcasting in the ultra-short wave range (VHF range) are increasingly antennas in the form of a monopole whose length in the LMK range is very short compared to the wavelength is and which cooperates with an electronic amplifier circuit used. Often, separate transmission paths are provided for amplifying the signals in the two frequency ranges.

In the application DE-AS 19 19 749 and DE-AS 23 IO 616 is. connected to the monopole a crossover, at the outputs of the transmission paths for the VHF and the LMK area are connected.

In DE-AS 19 19 749 the transmission path for the LMK range is connected via an inductance and the transmission path for the VHF range via a capacitance to the monopole. According to Fig. 1, the coupling capacitor C 2 for the VHF range is parallel to the input of the transmission path for the LMS range because the input of the transmission path for the VHF range is always a coil Contains L 2 as part of a parallel resonant circuit,

Fig. 2 shows in simplified form the replacement image of the arrangement of Fig. 1, as it is effective upon receipt of the LMK area. The short reception monopole acts as a signal source with the signal voltage U = E, hr _f , whose source impedance consists of the antenna capacitance C 1 and a very small, for this consideration negligible, series resistance. , E = electric field strength at the location of the antenna, h _f r =

6 Γ Τ

effective amount of monopoly,

In series with C 1, upon receipt of the LMK range, the coupling capacitance C 2 for the VHF range and, parallel to it, the input impedance of the electronic amplifier circuit which, for example, when using a field effect transistor essentially consists of a capacitance C 3, C 1 together with C 2 and C 3, a capacitive voltage divider, so that the control voltage U _st for the electronic amplifier circuit is substantially smaller than U _Q , as soon as the sum of C 2 and C 3 is greater than C 1.

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^U St = ^U S

C 1 + C 2 + C 3

Especially with short monopolies, the capacitance C 1 is very small, so that the control voltage Ug _t for the LMK range at a relatively large C 2 and C 3 is significantly reduced. This shows that with a capacitive coupling of the

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transmission path for the VHF range, the sensitivity of the electronic antenna in the LMK range is adversely affected.

In the case of transmitting the VHF range, the equivalent circuit shown in Fig. 3 is effective. In most electronic antennas with separate transmission modes for LMK and FM, a bandpass filter is implemented for uniform transmission of the FM band. The primary circuit is formed from the capacitive source impedance of the antenna R 1 / C 1, from L 1 and the input impedance of the amplifier for the LMK range consisting essentially of a capacitance C 3. The secondary circuit consists of L 2 and C 4 and the input impedance of the subsequent transmission path for the VHF range, through C 2, the filter is capacitively coupled. As just stated, this coupling capacity is detrimental to the reception of the LMK range.

In a further solution specified in the application DE-AS 23 10 616, the load capacitance at the input of the transmission path for the LMK range can be reduced by transforming the signals of the VHF range. Fig. 4 shows the equivalent circuit diagram. it is effective for the transmission of the FM and LMK area. The primary and secondary resonance allows a loose coupling of the coils L 1 and L 2, ie, the distance can be chosen so that there is a lower capacitive load on the amplifier input for the LMK range. The primary circuit is formed from the capacitive source impedance of the antenna R 1 / C 1, L 1 and the substantially consisting of a capacitance C 3 input impedance of the amplifier V 1 for the LMK range. The secondary circuit is formed by L 2, C 4 and the input impedance of the subsequent transmission path V 2 for the VHF range, by electric fields of the atmosphere, by R _e ibungselektritzität or by touching the antenna rod with electrically charged bodies, which caused by flashovers AC voltage destroy the Eingangransransietor the Übertragungsunqsweges for LMK area. For the purpose of

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limitation of these voltages, a protective diode D 1 is often provided. From the secondary side of the transmitter for the FM range, an additional impedance is transformed to the primary side, which causes a deterioration of the sensitivity in the LMK range. This and the unavoidable capacitive loading of the input of the LMK amplifier through the capacitance between the two coils of the FM transmitter are the disadvantages of this solution. .

In the application DE-OS 21 15 657 a circuit arrangement is specified, in which the different frequency ranges are amplified together in a field effect transistor, and the separation takes place on different transmission paths such that at the source of the lower frequency range and at the drain of the upper frequency range are coupled. By separating the signals of the upper and lower frequency range on separate transmission paths at the output of a field effect transistor, the o. G. However, in order to avoid additional capacitive loading at the gate of the field effect transistor and to improve the sensitivity in the lower frequency range, circuit arrangements in which the signals of the different frequency ranges in active elements are jointly amplified have, in contrast to the described circuit arrangements with separate transmission paths u, a. Significantly worse bulk signal properties, since the nonlinearity of the transfer characteristic, the signals of the upper and lower frequency range interfere with each other, so that the disadvantages outweigh total ».

The in Funkschau 1976, Issue 14, page 578 ".,. 580 given circuit principles' represent the current state of the art of electronic car antennas, There are clearly illustrated the particular problems of separation of the signals of different frequency ranges on separate transmission paths. In this publication, known authorities in the field of experts believe that a further improvement in the sensitivity

Speed of electronic car antennas in the LMK range for a given length of the antenna rod is no longer possible.

d) Object of the invention

The aim of the present invention is to improve the sensitivity of electronic antennas, which receive in a lower and an upper frequency range, for example in the LMK and VHF range, compared to electronic antennas' with a crossover between receiving * antenna element and the amplifiers for different frequency ranges, to improve in the lower frequency range and at the same time to obtain the favorable large signal characteristics of these known solutions with separate transfer cars.

e) Explanation of the nature of the invention

The object of the invention is to avoid common amplification of the signals of both frequency ranges in this electronic amplifier element in electronic antennas, in which the signals of the upper and lower frequency range are supplied together to a first electronic amplifier element. The object is with the antenna for multiple receiving areas with electronic amplifier, which has the form of a dipole or monopole and receives in a lower and an upper frequency range and in which the length of the dipole or monopole is very short compared to the wavelength of the lower frequency range and the Separation of the signals of the lower and upper frequency range on separate Obertragungswege at the output of the first electronic amplifier element is such that the signals of the lower frequency range by means of an inductance, which largely blocks the signals of the upper frequency range, coupled at the source, for example, a Feldef f el <11 ransistors be solved in that the signals of the upper frequency range also at the source by means of a capacitance which blocks the signals of the lower frequency range largely, coupled out and between the source and drain of the field effect transistor

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in the upper frequency range substantially lower impedance than all other impedances acting in the drain and source branches are connected. This impedance, on the other hand, must be sufficiently high impedance in parallel with all other lower frequency range impedances active between the source and reference potentials versus the low frequency range input impedance to avoid negative effects on the frequency response of the gain in that frequency range. Required is o, g. Impedance between the drain and source to largely suppressed by the field effect transistor currents of the upper frequency range in the source branch by approximating short circuit of the drain-source path, so that their influence on the transmission behavior of the transmission path for the upper frequency range is negligible. This impedance may be, for example, a capacitance or a series resonant circuit. Furthermore, an inductive impedance which is sufficiently high-impedance in the upper frequency range and sufficiently low-impedance in the lower frequency range must be connected in the drain lead. It ensures that the series connection of the impedance between the drain and source of the field effect transistor with the impedance switched on in the drain line is high-impedance in the upper frequency range and thus does not influence the transmission behavior for the upper frequency range. In the lower frequency range, the impedance of this inductance is negligible, so that the field effect transistor operates in drain circuit. The inductive impedance in the drain lead of the field effect transistor forms a parallel resonant circuit together with the capacitors acting between drain and reference potential. The resonant voltage of this circuit is fed back via the impedance between drain and source to the source electrode, so that the oscillation condition can be met. The oscillation of this stage can be avoided with certainty if the quality o. Resonant circuit is sufficiently reduced. This is possible by connecting a resistor in parallel to the inductance.

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In the case of the transmission of the upper frequency range, it proves to be advantageous in terms of sensitivity and selection to make the circuit connected to the coupling-out capacitance, together with the capacitive source impedance of the antenna, with a separation capacitance and an inductance between the gate of the field effect transistor and the passive antenna element, the input capacitance of the field effect transistor and the Auskoppelkapazität results in a resonant circuit or a bandpass filter and the connection to the transistor of the transmission path for the upper frequency range is such that a favorable signal-to-noise ratio is achieved «De required bandwidth and uniformity The gain in the transmission range, there are various ways to design the following on the Auskoppelkapazität circuit of the transmission path for the upper frequency range. If the transmission behavior of a single circuit is sufficient, the input of the amplifier transistor of the upper frequency range can be connected to the coupling-out capacitance in the simplest case. Its input impedance is thus part of the resonant circuit for the upper frequency range. Further possibilities for designing the Übertragungsver halteris and the signal-to-noise ratio in the upper frequency range obtained when instead of Auskoppelkapazität a capacitance directly or the decoupling capacitance is connected via an inductance to the reference potential and the input of the amplifier for the upper frequency range parallel to this capacitance or to this inductance is turned on. The use of a single circle for selection and transformation has the advantage of lower insertion loss at the resonant frequency than a bandpass filter. With greater required bandwidth in the upper frequency range, for example in the VHF range, it proves advantageous to insert a band filter with critical or slightly supercritical coupling between the passive antenna element and the amplifier for the upper frequency range.

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There are many possibilities for the realization. All known coupling types can be used. Compared with the application DE-AS 23 10 616 a much higher degree of freedom is given to the design of the transmission path for the upper frequency range. Between o. G. Selection means and the input of the amplifier for the upper frequency range can be switched further improving the transmission behavior and the signal-to-noise ratio improving impedances. The diode for protecting the field effect transistor from high voltages can be advantageously switched between the gate of the field effect transistor and the input of the transmission path for the upper frequency range, if it is connected by a coil of low inductance with the reference potential.

With the circuit arrangement proposed here according to the invention, further improvements over known circuit arrangements result, so that the previous prejudice of the experts with the solution according to the invention can be considered eliminated. The essential feature of the overcoming lies in the fact that the signals of the upper and lower frequency range pass through a common transmission path while avoiding additional load capacitances to the gate of a field effect transistor or a similarly acting amplifier element according to the invention in the upper frequency range by sufficiently low-impedance shunt to the drain-source Distance between gate and source acts as a capacitance that is part of a selective, linear transmission network of the upper frequency range in which no gain occurs. Since, in contrast to the application DE-OS 21 15 657 only the lower frequency range is amplified in the first electronic element, non-linear effects are substantially reduced, whereby the circuit ensures significantly more favorable large-signal characteristics.

In the following, the invention will be explained in more detail by exemplary embodiments,

Fig. 5 shows the circuit arrangement of the inventive solution with minimal effort. In the case of transmitting the upper frequency range, the capacitive source impedance of the passive antenna element is C l / R 1, the separation capacitance C 5, the circular inductance L 1, the input capacitance of the field effect transistor C 3, the coupling-out capacitance C 6 and the input impedance of the adjacent one -Obertragungsweges the upper frequency range components of a resonant circuit. In the simplest case, the amplifier transistor for the upper frequency range is connected directly to the coupling-out capacitor C 6. Thus, its input impedance is part o. G, resonant circuit. C 7 forms in the upper frequency range a very low-impedance shunt to the drain-source path of the field effect transistor V 1 and thus prevents as far as possible that flow through the field effect transistor V 1 currents of the upper frequency range between source d and reference potential. With suitable dimensioning of the resistor R 3, the oscillation of this stage is suppressed. Furthermore, the series connection of C 7 and L 6 / R 3 in the upper frequency range is still sufficiently high-impedance, so that no significant influence on the transmission path of the upper frequency range occurs. In the case of the transmission of the lower frequency range, the impedances of the inductors Ll, L 3, L 6 and those of the capacitances C 6 and C 7 are negligible, so that the field effect transistor V 1 operates in drain circuit. At the source resistance R 2 v. 'The signal of the lower frequency range via C 8 is coupled out.

Other possibilities for the design of the transmission behavior and the signal-to-noise ratio in the upper frequency range is obtained when, as in Fig. 6 instead of the Auskoppelkapazität a capacitor C9 is connected to reference potential and is connected parallel to the capacitance of the amplifier for UEs upper frequency range, which must be high impedance in this circuit variant in the lower frequency range, ^ -

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According to FIG. 7, an inductance L 4 is connected to reference potential in series with the coupling-out capacitance C 6. Parallel to L 4, the amplifier for the upper frequency range is connected.

In Fig. 8, the transmission path of the upper frequency range is designed as a bandpass filter with inductive base point coupling. The primary circuit is formed from the components already mentioned in the description of FIG. 5 and the inductance L 4 common to the primary and secondary circuits. The secondary circuit also consists of L 5, C 4 and the input impedance of the amplifier for the upper frequency range.

In this circuit arrangement, the diode D 1 can advantageously be connected between the junction of C 6 and L 4 and the gate of the field effect transistor V 1 with regard to the transmission behavior in the upper frequency range.

Claims (11)

- Ii - Invention claims · 1, antenna for multiple reception areas with electronic
Amplifier in the form of a dipole or monopole
and in one, lower and an upper frequency range, wherein the length of the dipole or monopole is very short of the wavelength of the lower frequency range and which is connected to the input of the electronic amplifier circuit in the form that the signals of both frequency ranges from the terminals of the dipole or monopoly over one
Separation capacitance (C 5) and a longitudinal inductance (L 1) to the control path of a first electronic amplifier element
(V 1) are transmitted with high-impedance capacitive input, wherein the capacitance of the dipole or monopole (Cl), the longitudinal inductance (L 1), the input capacitance (C 3), for example, a field effect transistor, and more between its source and the B _e Train impedance arranged frequency-determining components of a resonant circuit of the upper frequency range are and the separation of the signals dos lower and upper frequency range on separate transmission paths at the output of the first electronic amplifier element
(V 1} such that the signals of the lower frequency range by means of an inductance (L 3), which largely blocks the signals of the upper frequency range, are coupled out at the source, for example, of a field effect transistor (V 1),
characterized in that the signals of the upper frequency range at the source by means of a capacitance (C 6), which blocks the signals of the lower frequency range largely coupled, and between the source and drain of the field effect transistor (V 1) in the upper frequency range substantially lower impedance (C " ⁷ J than everyone else in the
Drain and source branch acting impedances is connected,
which in parallel with the coupling-out capacitance (C 6) of the upper frequency range in the lower frequency range still has a sufficiently high impedance to the input impedance of Obertraguncsweges the lower frequency range, and further that in the Droinzuleitung the field effect transistor located inductive impedance (L 6) designed so is that it is sufficiently high-impedance in the upper frequency range, sufficiently low-impedance in the lower frequency range, and that the quality of the parallel resonant circuit formed by these and the effective at the drain of the field effect transistor (V 1) capacitances on the resonant frequency is so low; that an oscillation of the step is avoided with certainty, 2, antenna according to point 1, characterized in that the coupling-out capacitance (C 6, FIG. 5) is connected directly to the input of the amplifier for the upper frequency range, 3, antenna according to item 1, characterized in that instead of the coupling-out capacitance (C 9, Fig. 6) is connected to reference potential and the output of the amplifier of the upper frequency range is coupled via a separation capacitance at the source of the field effect transistor, wherein the input impedance the amplifier of the upper frequency range in the lower frequency range must be high impedance, 4, antenna according to point 1, characterized in that between the coupling-out capacitance (C 6, Fig. 7) and the reference potential, an inductance (L 4) is connected and connected in parallel to the amplifier of the upper frequency range, 5, antenna according to item 1, characterized in that the to the Auskoppelkapazität (C 6, Fig, 8) subsequent circuit arrangement is designed so that between the terminals of the passive antenna and the terminals of the amplifier for the upper frequency range, a band filter with inductive Foot point coupler.g is realized, 6, antenna according to item 1, characterized in that the circuit arrangement adjoining the coupling-out capacitance (C 6, Fig. 5) is designed such that between the terminals of the passive antenna and the - 13 - fcv »» .. '* < Connections of the amplifier for the upper frequency range a band filter is realized with any type of coupling. 7, aerial, according to point 1 to 6 "e g e k e. η η ζ e i c h η e, t 'd a du rc h, that between the selection means and the input of the amplifier for the upper frequency range more the transmission behavior and the signal ~ noise-distance improving impedances are connected, 8, the antenna according to item 1, characterized in _t that the impedance between the drain and source of the field effect transistor a capacitance (C 7, Fig, 3), 9, antenna according to point 1, characterized in that the impedance between the drain and source of the field effect transistor is a Reihenschvvingkreis, 10. Antenna according to item 1, characterized in that the quality of the inductance in the drain lead of the field-effect transistor is reduced by connecting a resistor in parallel (R 3, FIG. 8), 11, antenna according to point 1, characterized d a d u r c h that a protective diode between the gate of the field effect transistor (V 1, Fig, 8) and the source of the remote terminal of the coupling-out capacitance (C 6) is turned on. Dazu_3_S8iten drawings