EP0336339B1 - Phase-shifting combiner for electromagnetic waves - Google Patents

Description

The invention relates to a phase shift combiner for electromagnetic waves.

In the phase-shifting combiners of the prior art, illustrated by the patent document US Pat. No. 4,602,227 and arranged in accordance with the preamble of claim 1, the phase-shifters are produced from line sections or from a hybrid coupler of which two accesses are provided with short-circuited lines.

Applications remain very limited because of the losses or mismatches they generate.

• les modulateurs à 2 ou 4 états de phase,
• les combineurs à déphasage,
• les guides à permittivité ou perméabilité variable.

Among the applications that are commonly used, we can cite:

• modulators with 2 or 4 phase states,
• phase shifters,
• guides with variable permittivity or permeability.

Among the devices of the prior art, the manual entitled "Microwave filters, Impedance matching, Networks and Coupling structures" by MATTHAEI (Mc Graw-Hill 1964) pages 872 to 887 describes a ring resonator which is a passive power multiplier device .

The object of the invention is to overcome the drawbacks highlighted above.

To this end, the invention provides a phase shift combiner for electromagnetic waves according to claim 1.

Advantageously, the principle of the phase-shifting combiner according to the invention is simple and its implementation easy.

It has the property of being associable in series or in parallel on condition of respecting the phase conditions of the function to be obtained.

In addition, it is tunable (frequency agility) by modifying the permeability or the permeability of its medium (propagation medium).

Depending on the selected propagation mode, it has low losses and provides little or no R.O.S. (Standing wave ratio) on the lines when its loop lengths and impedances are optimized and the coupling is adjusted.

• un déphaseur adapté,
• un combineur réversible (simple ou multiple),
• un commutateur adapté.

These various advantages make it, in particular:

• a suitable phase shifter,
• a reversible combiner (single or multiple),
• a suitable switch.

• la figure 1 illustre schématiquement un déphaseur utilisé dans le combineur à déphasage de l'invention ;
• les figures 2 à 8 illustrent différentes formes de réalisation du combineur à déphasage de l'invention ;
• les figures 9 et 10 représentent deux courbes illustrant le fonctionnement respectif des combineurs des figures 6 et 8.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of nonlimiting example, with reference to the appended figures in which:

• Figure 1 schematically illustrates a phase shifter used in the phase shifter of the invention;
• Figures 2 to 8 illustrate different embodiments of the phase shift combiner of the invention;
• FIGS. 9 and 10 represent two curves illustrating the respective operation of the combiners of FIGS. 6 and 8.

• une première ligne de transmission d'entrée 10 d'impédance caractéristique Zo à une fréquence f,
• une seconde ligne de transmission de sortie 11 d'impédance caractéristique Zo à la fréquence f,
• un coupleur hybride 12,
• une troisième ligne de transmission de boucle 13, d'impédance caractéristique Zo à la fréquence f.

The phase shifting combiner of the invention, represented in FIG. 2, has at least one phase shifter according to FIG. 1, the latter comprising:

• a first input transmission line 10 of characteristic impedance Zo at a frequency f,
• a second output transmission line 11 of characteristic impedance Zo at the frequency f,
• a hybrid coupler 12,
• a third loop transmission line 13, of characteristic impedance Zo at the frequency f.

• E1 = 1 (avec une phase = 0)
• E2 = (1-c²)^1/2 (avec une phase = 0)
• EB1 = c (avec une phase =π/2)
• EB2 = c e^{-(α +jβ) l} (avec une phase βl = 2π l/λ et π/2

avec

c :

coefficient de couplage en tension

l :

longueur de la boucle d'impédance Zo

α :

coefficient d'affaiblissement

β :

coefficient de propagation

λ :

longueur d'onde avec λ = Cl/f : (Cl célérité de la lumière, f fréquence d'utilisation )

   Si on considère les simplifications suivantes :

α =

0 lignes sans pertes (ou très faibles pertes)

$\text{βl = n.2. π ⇒ l=nλ}$

   En régime établi, nous obtenons :

${\text{E2 = (1-c²)}}^{\text{1/2}}\text{+ c . EB2}$

avec

et qui, reportée dans E2, fournit l'équation :

   Lorsque le coefficient de couplage est à -3dB

$$\text{c = 10⁻}\frac{\text{3 }}{\text{20}}\text{≃ 0,71}$$

nous obtenons pour expression de E2

${\text{E2 = -1 ⇒ E2 = E1.e}}^{\text{jπ}}$

   L'onde E1, après passage dans le déphaseur à boucle de l'invention, subit un déphasage de π(180°) lorsque la longueur (l) de la ligne résonante (boucle) est un multiple de λ (n=1, 2,..., etc).We can write the electric fields at the origin:

• E1 = 1 (with a phase = 0)
• E2 = (1-c²) ^1/2 (with a phase = 0)
• EB1 = c (with a phase = π / 2)
• EB2 = ce ^{- (α + jβ) l} (with a phase βl = 2π l / λ and π / 2

with

vs :

voltage coupling coefficient

l:

length of the Zo impedance loop

α:

weakening coefficient

β:

propagation coefficient

λ:

wavelength with λ = Cl / f: (Cl speed of light, f frequency of use)

If we consider the following simplifications:

α =

0 lines without losses (or very low losses)

$\text{βl = n.2. π ⇒ l = nλ}$

In established regime, we obtain:

${\text{E2 = (1-c²)}}^{\text{1/2}}\text{+ c. EB2}$

with

and which, reported in E2, provides the equation:

When the coupling coefficient is -3dB

$$\text{c = 10⁻}\frac{\text{3}}{\text{20}}\text{≃ 0.71}$$

we get for expression of E2

${\text{E2 = -1 ⇒ E2 = E1.e}}^{\text{jπ}}$

The E1 wave, after passing through the loop phase-shifter of the invention, undergoes a phase shift of π (180 °) when the length (l) of the resonant line (loop) is a multiple of λ (n = 1, 2 , ..., etc).

• Il est utilisable dans toutes les structures de propagation qui permettent la réalisation de coupleurs hybrides ou (T) associés à des lignes de transmission.
• Il est utilisable pour tout type d'ondes électromagnétiques Ex : H.F. (High Frequency) ; U.H.F. (Ultra High frequency) ; VHF (Very High Frequency) ; Optique cohérente.
• Il est utilisable avec tous supports de propagation pour ondes électromagnétiques (lignes de transmission)

   Ex : coaxial ; micro-ruban ("microstrip"); triplaque ; guide d'onde ; fibre optique...The field of application of the device of the invention is as follows:

• It can be used in all propagation structures which allow the creation of hybrid couplers or (T) associated with transmission lines.
• It can be used for all types of electromagnetic waves Ex: HF (High Frequency); UHF (Ultra High frequency); VHF (Very High Frequency); Coherent optics.
• It can be used with all propagation media for electromagnetic waves (transmission lines)

Ex: coaxial; micro-tape ("microstrip");triplate;waveguide; optical fiber...

• n faible" avec c égal ou non à -3dB on obtient alors un déphaseur non sélectif quelconque
• n élevé avec c égal ou non à -3dB on obtient alors un déphaseur sélectif.

In alternative embodiments, we consider:

• n weak "with c equal or not to -3dB then we obtain any non-selective phase shifter
• n raised with c equal or not to -3dB we then obtain a selective phase shifter.

$\text{avec ε = εo. εr εo = λ/(36.π.10⁹)}$

$\text{et µ = µo. µr µo = 4. π.10⁻⁷}$

   Si l'on considère à présent le cas des hyperfréquences, suivant l'expression des phases, deux coupleurs hybrides en cascade permettent, en sortie, une recombinaison de l'onde sur l'accès opposé (annulation des ondes sur la deuxième sortie).For the tunability of the phase shifter according to the invention, one can play on the relative permeability εr or the permeability µr of the medium supporting the propagation: indeed an electromagnetic wave propagates with a speed of

${\text{v = (ε. µ)}}^{\text{1/2}}$

$\text{with ε = εo. εr εo = λ / (36.π.10⁹)}$

$\text{and µ = µo. µr µo = 4. π.10⁻⁷}$

If we now consider the case of microwaves, according to the expression of the phases, two hybrid couplers in cascade allow, at output, a recombination of the wave on the opposite access (cancellation of the waves on the second output).

An equivalent principle highlights the recombinations with "magic T".

• faibles pertes en transmission,
• bon R.O.S. aux accès,
• bon découplage entre accès.

The use of loop phase shifters according to the invention offers the possibility of acting on the phase of one or of the two inputs while retaining the desired properties of the system; that is to say :

• low transmission losses,
• good access ROS,
• good decoupling between access.

Thus, with a low value of n, a microwave switch can be produced by considering, as shown in FIG. 2, two phase shifters according to the invention 20 and 21 whose inputs are connected to the outputs of a first hybrid coupler 22 and whose outputs are connected to the inputs of a second hybrid coupler 23.

The insertion between the two hybrid couplers 22, 23 of a phase shifter (20, 21) on each link provides the phase variation to two states whose bandwidth is widened by the offset of the two phase shifters 20 and 21.

The action on the permeability εr or the permeability µr of the medium provides the state of the outputs.

To make a loop combiner with a high value of n, as shown in FIGS. 3 and 4, a cell 14 is used in which one of the two inputs or one of the two outputs is connected to a suitable termination R .

Selectivity is the function sought here (application to connections).

Its definition allows summation (2 inputs-1 output) or differentiation (1 input-2 outputs).

Here the variation on the permeability µr or the permeability εr of the medium creates the frequency translation of the phase shifted access therefore its tunability (agility).

The cascading of n cells 14, as represented in FIG. 3 for example, makes it possible to produce a multiplexer with n + 1 inputs represented in FIG. 5, which by application of the principle of the reciprocity of any passive element is a demultiplexer with n + 1 outputs.

Any other arrangement by interpenetration of the loops is also conceivable.

In an exemplary embodiment, represented in FIG. 6, there is obtained a double loop combiner, with two inputs and one output such that this combiner comprises a hybrid input coupler 30 and a hybrid output coupler 31, two phase shifters according to the invention (32, 33 and 34, 35) being arranged in cascade respectively between the first output of the input coupler 30 and the first input of the output coupler 31 and between the second output of the input coupler 30 and the second output coupler input 31.

• deux demi-coquilles métalliques obtenues par fraisage, munies à l'extérieur d'un radiateur, dont l'une d'elles 40 est représentée sur la figure,
• une prémière boucle 37 en INVAR,
• une seconde boucle 38 en INVAR.

The assembly 36 of the two phase shifters 32 and 34 can be produced in the same housing shown in FIG. 7 which comprises:

• two metal half-shells obtained by milling, provided on the outside with a radiator, one of which 40 is shown in the figure,
• a first loop 37 in INVAR,
• a second loop 38 in INVAR.

The two half-shells are assembled, in the plane of the figure, by screen-printed deposition of solder paste.

The half-shell 40 shown has bosses 41 which correspond on the other shell to tuning screws. On each of the loops 37, 38 is disposed a quartz blade of agreement 42, 48.

The two loops are made of INVAR to guarantee temperature stability.

• longueur du boîtier 11 ≃ 500 millimètres
• largeur du boîtier 12 ≃ 250 millimètres
• longueur de la première boucle 37 ≃ 400 millimètres
• longueur de la seconde boucle 38 ≃ 390 millimètres

on obtient les performances suivantes pour le combineur à double boucle à deux entrées et à une sortie de la figure 8 :

• une bande de fréquence de 5,85 à 6,425 MHz.
• R.O.S. aux accès < 1,2
• Pertes entre la première entrée E1 et la sortie S < 0,2dB dans ± 18MHz
• Pertes entre la seconde entrée E2 et la sortie S < 0,2dB
• Découplage entre les deux entrées E1 et E2 > 20dB

   La courbe représentée sur la figure 9 illustre la recombinaison de la deuxième entrée E2 vers la sortie S.With the following dimensions for a housing:

• case length 11 ≃ 500 millimeters
• case width 12 ≃ 250 millimeters
• length of the first loop 37 ≃ 400 millimeters
• second loop length 38 ≃ 390 millimeters

the following performances are obtained for the dual loop combiner with two inputs and one output of FIG. 8:

• a frequency band of 5.85 to 6.425 MHz.
• ROS access <1.2
• Losses between the first input E1 and the output S <0.2dB in ± 18MHz
• Losses between second input E2 and output S <0.2dB
• Decoupling between the two inputs E1 and E2> 20dB

The curve shown in Figure 9 illustrates the recombination of the second input E2 to the output S.

It would also be equally possible to produce the assembly of the two parts 36 and 39 and even the assembly of the double-loop combiner of FIG. 6 in a housing with two half-shells such as that shown in FIG. 7.

Another possible embodiment is illustrated in FIG. 8, where, unlike FIG. 6, only one phase shifter (32, 34) according to the invention is used on each channel.

The signal represented in FIG. 10 is then obtained, which illustrates the recombination of the first input E1 towards the output S.

It is understood that the present invention has only been described and shown as a preferred example and that its constituent elements can be replaced by equivalent elements without, however, departing from the scope of the invention.

Claims (6)

1. A phase shifting combiner for electromagnetic waves, the combiner comprising at least one cell (14) constituted by an inlet hybrid coupler (22), with outlets phase-shifted at 90° from each other, an outlet hybrid coupler (23), with outlets phase-shifted by 90° from each other, and two phase-shifters (20, 21), each included between one of the two outlets of the inlet hybrid coupler (22) and one of the two inlets of the outlet hybrid coupler (23), characterized in that each cell (14) is constituted by a hybrid coupler (12) with outlets phase-shifted at 90° from each other, where a first inlet is coupled with the outlet of an inlet hybrid coupler (22), and a first outlet is coupled with the inlet of the outlet hybrid coupler (23), its second outlet being coupled with its second inlet via a looped transmission line (13) so that the signal applied to the said first inlet of the cell (14) arrives at its first outlet at a frequency determined by the transission characteristics of the looped transmission line, with it being possible to control the phase-shifting through action on the said transmission characteristics, which can reach 180°.
2. A combiner according to claim 1, characterized in that one of its inlets or one of its outlets is connected to a matched load (R).
3. A combiner according to claim 2, characterized in that it comprises a plurality of cells (14) disposed in cascade.
4. A combiner according to claim 1, characterized in that it comprises an inlet hybrid coupler (30) and an outlet hybrid coupler (31) with one of the outlets thereof being connected to a matched load, at least one phase-shifter (32, 34) being disposed respectively between the first outlet of the inlet coupler (30) and the first inlet of the outlet coupler (31) and between the second outlet of the inlet coupler (30) and the second inlet of the outlet coupler (31).
5. A combiner according to claim 4, characterized in that it comprises a housing constituted by two metal half-shells to which two loops are coupled.
6. A combiner according to claim 5, characterized in that the two half-shells are assembled together by silkscreen deposition of a solder paste, with the two loops (37, 38) being made of INVAR.

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