DE1566967A1 - Antenna arrangement - Google Patents

Description

DR. CLAUS REINLÄNDER
DlPL-ING. KLAUS BERNHARDT

D-8 MUNICH 8
ZEPPELINSTRASSE 73 '

9/16

AMPBiENOI CORPORATION 2801 South 25th Avenue Broadview, 111. 60153, USA

Antenna arrangement

The invention relates generally to antenna assemblies and, more particularly, to methods and gate directions for increasing the Signal to Noise Ratio in Antenna Systems Appropriate for Use are determined in the low frequency bands.

Overseas radio links are mostly at signal operating frequencies executed within the low frequency bands and the very low frequency bands, the following are collectively referred to as all low frequency bands, since the Underwater transmission of radio signals, especially within this frequency bands is practically feasible. Underwater * radio arrangements are e.g. at frequencies within a Band operated from about 3 kHz to 300 kHz, operation at a frequency of 20 kHz is common.

009818/0827

SAD

1561917

Such Hiederfrequenz-Fimkverblndungsajiordnungen generally use fixed or rotating loop antennas, one of which has been found to be the leißtungskennlinien best available eye distance in the area of water in relation to the ^, give the directivity and the Signalstäxke. Usually, a variable capacitive reactance is connected as an impedance impedance in parallel to the loop antenna in order to enable the antenna to be selectively tuned for operation at more than one frequency. Since the overseas link assemblies operate at relatively low frequencies, a loop antenna and a variable capacitance having a relatively large inductance and a capacitance having a large serviceable size are generally required.

With previously known underwater termination arrangements and in particular with underwater radio reception arrangements in the area The large impedances of the loop antenna and the variable tuning capacitance have a very low frequency substantial noise of the boar parts and related Sciialtungsverluste introduced what leads to the ! «Sensitivity of the lap catching arrangement is reduced» I) IeSi Reduction in sensitivity is. Especially in the Low frequency bands are disadvantageous because Uer has high levels of the atmospheric noise and interference from electrical equipment meet there. That is why it has long been desired

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the signal-to-noise ratio of such underwater catchment arrangements to improve.

In many cases, increasing the effective height increases the antenna arrangement for the amplitude of the input signal the receiver and thus increases the signal-to-noise ratio of the receiver. However, Ee is usually difficult to determine the effective level of To enlarge antenna arrangement due to practical limitations on a submarine.

The introduction of a common gate amplifier between the Antenna arrangement and the receiver input would if by doing this Also the size of the signal to the receiver is increased, also increasing the size of the noise that is in the antenna circuit is present and could also add additional component noise created in the preamplifier itself. Likewise is the use of conventional passive filter networks, although these 'make up some of the noise from the receiver arrangement ruled out, in particular not effective for increasing the signal-to-noise ratio because of the significant reduction in signal amplitude, caused by the filter network); will.

Accordingly, one purpose of the inventor is to provide a method to increase the signal-to-noise ratio in matched loop antenna arrangements for use in the (low frequency bands to create.

An additional purpose of the invention is to provide an improved one

0 0 9818/0827 BAD ORIGINAL. =

To create sole loop antenna assembly for use in the low frequency bands, the antenna assembly being a results in a smaller operating bandwidth and a larger output signal amplitude than similar, known antenna arrangements .

Another purpose of the invention is that of the above mentioned reducing the operating bandwidth and increasing the output signal amplitude of tuned loop antenna systems through the use in such antenna arrangements of circuit devices to obtain »the relatively small dimensions and be light in weight.

Another purpose of the invention is to create a negative Impedance network to be used to increase the sensitivity and selectivity of a tuned mederfrequency loop antenna arrangement to varbessem.

Briefly stated, the invention consists in coupling a circuit device with negative impedance to a tuned loop antenna arrangement in order to effectively eliminate a substantial part of the loss of attitude occurring in the antenna arrangement. The resulting signal, which is generated by the antenna arrangement and the negative impedance device, is fed to the active input stage of the receiver. Ia the B8i; friction bandwidth and the output signal amplitude of the coordinated Aat-bucket arrangement of the '. Depending on the solvency losses occurring in the arrangement, there is a reduction

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«. 5 -

the (size of the circuit losses result in a reduced bandwidth and an increased output signal amplitude. The increased signal amplitude together with a reduced noise level, generated by the decrease in bandwidth is used consequently to increase the house spacing of the antenna arrangement. The invention is also optional in arrangement means for tuning the tuned antenna arrangement to selected operating frequencies within the low frequency bands and for simultaneously adjusting the magnitude of the negative impedance produced by the circuit means with. negative impedance is generated, thereby reducing the operating bandwidth of the Aatannenanordnuxig over a large range of the selected Befez*i@bs£.i: to keep equen3eH almost constant.

Exemplary embodiments of the invention are shown in the drawing shown, namely are

Mg «1 a schematic diagram of a coordinated antenna

aaox \ inmig according to the invention, 2 shows the equivalent circuit diagram of the tuned antenna arrangement

after. Pig. 1,
3? L £ c 3 a graphical representation of the improvement in the quality factor "Q" of a tuned antenna arrangement,

obtained by the invention, 3? ig. 4 is a graph showing the improvement in Figure 9 shows output signal amplitude of a tuned antenna arrangement obtained by the invention;

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·· ο * ■ *

5 shows a circuit diagram of a tuned antenna arrangement according to a further embodiment of the invention.

Grezaäß FIG. 1 contains an antenna arrangement, a loop antenna 10 which is connected by means of lines 14 to a complete radio reception arrangement 12. The antenna 10 can have any known loop * mtenne, but contains 3ΐώ im. If necessary, if a greater number of braht coils are wrapped around a relatively large support, a sufficient number

AnteimenbcVie for the. Signal reception in the low frequency : .u received, For Üntirsae signaling applications, the Advice 10 i> a all.ie ^ ieintm in sinea substantial distance voa dem

12 arranged and oeshalb the lines 14 ei-ir; Extend length of a few 103 feet (50 m). In the case of the innecoB3i.ere.ade2i! '

zn the grinding ^{anantezme 10 Ls 1} ; a changeable capacity; 6, i9öchrüfcet which: Ln d ^ r size 3 selelct.lv ^ eändart to "iiw inö.ur: -iive Ärtea-ie 10 ab.si.sfciaaten _s Tim a beatiaaate Betriebsfracuen7 / ianerb £. lb the ■ ^{iiederfrequeE..5b.} Indian _t which can catch the antenna 3ja.j.> aufü-uiaeiiiaen, although Ii r capacitance 16 is illustrated as ISI ₃ as they oc took ISRE SciL3.eLfe 10 is arranged, can aie be activated in other lnaktsn lä ^ sd ^ r I4 lines. Although en typically within the Bandea of j ^ Hz to 300 kHz

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used for underwater signaling like this is mentioned above, frequencies within a band of 5 kHz to 100 kHz are particularly in the specified arrangement Interest. Because of the large size of the antenna 10 includes in the Practice the capacity 16 usually a plurality of small ones Capacities provided with a coupled switching arrangement to provide sufficient capacity for selective tuning the antenna arrangement. Again because of the large size the antenna 10 and, in addition, because of the large number of capacities required, large losses are in the Arrangement introduced which, by their nature, are mainly are travel-oriented. These losses are tending to the received signal to attenuate and increase the bandwidth of the system, whereby the signal-to-noise ratio of the output signals of the arrangement is the opposite being affected.

In accordance with the invention, a negative impedance circuit 18 is coupled to loop 10 and capacitance 16 to provide the to supply improved resultant signal to point receiver 12.

The circuit 18 with negative impedance is, as shown, connected in parallel to the antenna arrangement 10, 16, where it is connected to it serves to effectively eliminate some of the circuit losses that occur in the antenna arrangement. the Negative impedance circuitry can be applied to the arrangement near the loop 10, near the receiver 12 or, as shown, on one Be coupled along the lines H intermediate point. In a

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In the manner described in more detail below, the onset of the circuit with negative impedance causes a reduction in the operating bandwidth of the antenna arrangement and an increase in the amplitude of the signal which is fed to the input of the radio receiver 12. Since the decrease in the bandwidth of the device reduces the received noise level and compensates for the increase in the effective resistance in the resonance with respect to the thermal noise level of the loop and capacitance, and as the amplitude of the output signal is increased, the signal-to-noise ratio of the resulting signal, which is obtained from the radio receiver 12, enlarged significantly.

With respect to negative impedance circuit 18, it should be noted that the ability to convert positive impedances to effective negative impedances by feeding the output of an amplifier back into its own input has long been known, and many circuits have been designed around this Get result. While any of the many known negative impedance circuits may be used in the present case, a known negative impedance transistor circuit is shown in FIG. It is circuit 18 is a push-pull converter with a negative impedance, which uses a feedback by a coupling between the two interconnected transistors 20 and 22nd The two transistors and their associated circuit elements are symmetrically arranged and commonly connected so that the output terminal of each transistor is connected to the common connection of the other translator

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mm Q m.

is coupled, whereby, a phase reversing feedback is avoided. The resulting magnitude of the negative impedance established by circuit 18 depends on the portion of the voltage applied to the circuit which is coupled between the transistors, and accordingly circuit 18 includes various variable bias voltage setting devices for setting the negative impedance. For a detailed description of the negative impedance circuit 18, reference is made to the article νοηλΟτ. Linvill, in IRE, Proceedings, 41 "June 1953" pages 726-729.

In addition, a variable load impedance 24 is provided in the circuit 18, thus enabling the size of the negative lapsdasaz to be changed simultaneously with the tuning of the antenna circuit. A mechanical coupling 26 is used for this purpose . connect the variable capacitance 16 with the impedance 'Zii .j to enable a simultaneous adjustment of the two rural elements au . From the following Be · ai-iKsiDimg show in detail that such a- » ..: .clgi? j? .1h position a balanced or essentially k .ßb-fittf Yei * b3ßserte bandwidth for the antenna arrangement f'i; Ibt _; / ef overall ii the s.bgeßtinsmte Betriebsfreq.uenz the antenna ./ H.ert, tilirj "Same tverständlieh is the mechanical control" ;;: liältüiti .i "ischea capacity 16 and the impedance 24!? iD .lafecrvjaiso be a complex puncture instead of a direct proportional relationship *

BATH ORIGINAL

The method of operation of the invention is shown in FIG. 2, in the equivalent circuit diagram of the loop antenna arrangement according to Pig. 1 is shown. The loop antenna 10 in Pig. 2 is generally represented by an equivalent inductance L and the variable tuning capacitance 16 is represented by an equivalent capacitance C in a tuning division. The total equivalent series resistance IL, of the tuned antenna arrangement is the resultant of the sum of all resistance losses in the circuit, aB of the winding and line resistance, the radiation resistance of the loop antenna and flCij equivalent series resistance of the antenna core losses. Yfie described above, the Terlustwiderstand R, üblicherweiaa iot for a tuned loop antenna arrangement "which is for the Yerwandimg in d. & N low frequency bands suitable for relatively large and this normally means that the sensitivity decreases arrangements leads.

The Ausgangsimp sa ar Z * ζ _t> by a conventional Schleifenantennenaz .Ordnung is formed when this is abgestiamt to resonance at a Betriebafrequena, can be represented as:

icrii X ^ the inductive resistance of the loop antenna and X « are the capacitive resistance of the capacitance.

The quality factor "Q * of the equivalent staggered antenna arrangement

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according to Fig. 2 let:

= X ₁ = IT ₀ (2),

where Xt and Rm are determined as in (1), while f is the operating resonance frequency of the tuned antenna arrangement and Δί the '' usual bandwidth of 3db of the tuned antenna arrangement which forms the effective operating bandwidth.

If a negative impedance -Z «according to the invention is parallel to the tuned antenna arrangement in a parallel connection with the loop L and the variable capacitance C, as in Pig. shown, switched- vii :: a, the effective resulting output impedance Z ₀ de>.

Z ₂ = (Z ₁ ) (-Zj ₁ ) (3 V ^Z 1 ~ ^Ζ 1Ϊ

Equation (3) shows that the antenna arrangement becomes stable when the absolute size of the negative impedance -Z is greater than the absolute size of the impedance Z ^, and that Z ^ is greater : as Z,> If dara i:! toward sine negative impedance -Zv predetermined G-Rosse is eingesetst parallel to a tuned Antennenarordnung according to the invention, one that wiiksame resultiereaöe impedance of the tuned antenna assembly is substantially

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about sr ·. ' Their normal size is increased.

From equation (1) it also follows that an increase in car AasgangsiEpedaiis; Z ^ of the matched antennas " arrangement au elnsn? antsj / rechendaa waste in the effective

; ^ ': S £ ia ⁺ »eij equivalent RaihenTor air resistance Rm of the coordinated Aiitsn * -" ensuing leads. As the axis of the equation (2) results, eric-at sic.a the quality factor Q of the antenna disorder

tzli (h ujc.ä we lcLane-bandwidth Af _ the An.ord'iung fäl3.t water · ÖE ¹ ierringoriing the Crröße IL, from Since the Au.i ^ arigoeifnal oie dia A asgangaspannung...? of the open circle of the abgoötiittxtuü A'ateu umanordnunr; ä: li * ekt is proportional to the size of Q in the arrangement »increases an increase of Q auoi. the Ai-sg8: -ff ^ 3iguül? .j £ pliti'i '3 _i which is formed by the agreed answer': ür.enanr rixi-u. Ι for hn Fanken-pfänger 12. 3) i3.-3 3rl /)> i '^; fm From {ingöät'tplio.ide aufaiaman with <iem A'ofall dt: 3 Rsjurci ·; f τ, ί.'s 1 · 3 ■: 'l ^ Tch t' .. \ '_ ΥίίΠ · ingcrung der Betriebs ~ bf.i «brr .-: *.', *? G ^ r Α · "/ :? άηυ · i _£ ; ei.tjg: ibi-3oht v / ird, v / • f" · er.; · .B? t ;; r ^: l .-. <»; ui «/ ·; ^3> ^; 4s do · '. ·
Xi ih.

i> jz 'Sz: · a_ i'li λ _- £ ■ ixr ^ h fi? ^ ιί1-ν? .. η {erLaltBuen Verb ΐιΐ ^^ χ- '/; : '· 9 ^! ./:.ί* <lr '.nie ii. ^ rj'ie:; ■): 'cYi'ing 3; ac> i c.cn Fi.ß. 1 r -: "ic.! Ii ₁ ;: ico. J? O: § ^ · .- .; ■> m2i :; ^v ·. Iror Λ'-ι-ί: iii nets 3Jx.er ^ θ ^ Ααίτε.ι! Inn ^ s. ".; r: · 'w \ -. Z - \ -'; a :;

# Jr / = AW * ^{60 Oh} -

£ ₀ - 20 Ms

ς = 40.

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. - 15 - half of the sea results from equations (1) and (2):

R ₁ «1.5 Obm

At - 500 Hz Z ₁ * 2400 - 360 ohms.

If a negative impedance -Zn with a value of -2670 + j73.4 ohms is used in parallel with the tuned antenna and in parallel with the variable capacitance, as Pig. 2 shows, then it follows from equation (?);

Z ₂ »24i10 ⁵ - j60 ohms.

Ba this value of Z _{2 is} now the effective resulting output impedance that is presented to the input of the receiver,. the effective series loss resistance R ^ and the band- > wide Δί of the antenna arrangement significantly reduced to:

β 0.15 ohm
= 50 Hz.

From equation (2) it follows further that equally Q of the circuit is increased by a factor of 10 to 400, which also causes a corresponding increase in the resulting Output voltage of the open circuit of the arrangement is effected. The above-mentioned significant improvements in the operating characteristics of the tuned antenna arrangement will be made without the Insertion of significant additional noise is achieved. In practice, the effective graded bandwidth of the present

Loop antennas can be reduced by a factor of 40, leading to

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leads to an improvement of 20 db below the noise threshold threshold sensitivity of 32 db. This consideration is very Roughly as it does not further reduce the atmospheric noise level caused by the reduced bandwidth is taken into account.

Fig. 3 shows the improvement in the quality factor "Q" of the tuned Antenna arrangement which is obtained by using a negative impedance rule as described earlier. The values were taken for a single loop antenna with a transverse winding and a 69.2 m line leading to the test arrangement. The PeId was supplied via a catenary test wire, which was excited with a signal voltage of 0.08 V and perpendicular was located to the center line of the loop winding. Fig. 4 shows the corresponding improvement in the output voltage thereof Antenna arrangement with the same test parameters.

Although the improved antenna arrangement according to the invention with a negative impedance circuit connected in parallel with the output of the tuned antenna, described wux de, can Similar improvements in the parameters of the antenna arrangement can also be obtained by adding a suitably designed negative Impedance circuit 18 * in series between the capacitance 16 'and the Radio receiver 12 * is used, as shown in Flg. 5 shows. In this training, the recipient can preferably be used as an entry level contain an amplifier, so that its usual active Circuit does not affect the negative impedance. Ia the effective terminal impedance Zrj of the arrangement is:

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where Zj ^{1 is} the equivalent impedance of the antenna 10 * and the tuning capacitance 16 ¹ and Z ^ is the impedance of the negative impedance circuit 13 *, in this case the absolute size of the negative impedance Z ^ must be smaller than the absolute size of the equivalent impedance ZS of Antenna circuit to avoid instability. The parallel circuit arrangement of FIG. 1 is somewhat preferable to the series circuit arrangement of FIG. 5, since in the former arrangement the negative impedance is parallel to the antenna terminals and therefore results in greater operational reliability and more error-prone operation.

Although this is not shown in the drawing, the negative series impedance 18 'could also be arranged between the loop 10 * and the capacitance 16 *, in which case the latter * directly with the usual input circuit of a receiver, such as 12 in Fig. 1 , is connected. As with the other disclosed embodiments, the selected negative impedance used has a value so as to largely, but not completely, eliminate the resistive loss of the LC array of ΙΟ'-Ίβ * in resonance. As a result, the thermal noise generated in the matched device, which determines the value of the smallest detectable signal for the receiving device, is not reduced because the decrease in bandwidth as Q is increased compensates for the increase in QZ _1.

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Claims (2)

/ for 9/16 claims 1. Antenna arrangement which is suitable for use in low-frequency bands, characterized by a tuned antenna device which can receive point signals in the low-frequency bands, the tuned antenna device being a loop antenna device, a capacitance device which is parallel to the loop antenna device for tuning the ijjtenneneinrichtung to a specific operating frequency is coupled within the low frequency bands, and contains an antenna output device which can be coupled to the radio receiver circuit device »whereby the operating bandwidth of the tuned antenna device and the amplitude of the output signal occurring at the output device depend on the looseness occurring within the tuned antenna device al: b8 ; i £ ig are »and by a circuit device with negative jj penance, which with the tuned antenna device for Einx \ 'hr-: r. a negative impedance is coupled to a quantity, CjC- s'.sreicr c * nd, to switch off a substantial part of the circuit list jbmerhalo of the tuned antenna device, whereby no unstable Zurataad is generated therein in order to (Irtei: to reduce the 3etr.1 bandwidth of the antenna arrangement ιιτά ii.e to increase the amplitude of the output 3igii8.1es. 0 0 9 818/0827 BATH 1568967 2. Antenna arrangement according to claim 1, characterized in that that the Sehaltüngseinrichtung with negative impedance in series iibetween the capacity device and the radio reception device is coupled and represents a negative impedance having an absolute value that is less than the absolute Value of the equivalent impedance of the tuned antenna device that occurs at the exit facility " 3 α antenna arrangement according to claim 1, characterized in that the circuit device is coupled with negative impedance in series κ between the capacitance device and the loop antenna device and represents a negative impedance which has an absolute magnitude smaller than the absolute magnitude of the equivalent Impedance of the matched antenna device. 4 · Antenna arrangement according to claim 1 »characterized in that that the circuit device is coupled with negative impedance in parallel to the tuned antenna device and one represents negative impedance that has an absolute value greater than the absolute value of the equivalent impedance of the matched The antenna device is attached to the output terminal device occurs. ^ 5 ο / mtfczmenanordnung according to claim 1, characterized in that the capacity direction and the circuit device with v3gat.lver impedance can be set in order to set the selected operating "of the antenna arrangement, and dad the antenna 009818 / aS27 BATHROOM OFÜGINÄt: in the At arrangement also contains a device, dlf iwieehen i ö.Le capacity device and the Schaltuögeeinriohtung lit is coupled to the fairness impedance, including the lapaiity device and the negative Iapedance device at the same time, uja generate an essentially constant bandwidth for the array over a wide range of the selected operating conditions: equena within the low frequency bands iu, 6, "V out to increase the Auagangs-RaUBchabstandeö tön äbgessimmten loop antenna assemblies bestiant for Yeiwendung in eng NiederirequenKbändern, wherein the Betriebebmdb-PAGE and the AusgangsBignalaiaplitude the antenna arrangement ton the switching loss occurring therein to depend, characterized gfjkeiinzeichaet _f that a substantial, However, not all of the Toil of the circuit losses occurring is turned off, is coupled Indea sine negative impedance means to the antenna array, characterized UNAE the UA the Betriebsbahdbreite the arrangement reduce eh and m increase the amplitude of the Ausgangssignälee, the resultant signal of the? unk8chaltungsiih ^ id £% Ueng Is supplied to dig the arrangement can be coupled irerdeh * Ί, method according to claim 6, dadureh gekenniei & Met, d & fi the 3iih! Additional seam change: on selected operating offices Iimfei-half of the low-frequency bands are satisfied ttifä UM oaJ equal to-2 (in the event the negative impedance is switched on substantial constant bandwidth over a wide range ■ Inr selected operations within the * received. 009S18 / 0827 BATH