[0001] The present invention relates to a system which allows the fast sectional scanning
of a bundle of radar antenna monopulses to be obtained. The invention is used in the
field of radar systems for tracking, particularly in the field of the components in
waveguides for antennas. Said fast scanning is obtained by the use of an electronic
ferrite switch in the waveguide. As no electronic solutions for shifting the bundle
were known, the only possibility consisted of very slow electromechanical devices
which therefore were not satisfactory when used for radar purposes.
[0002] The following description of the figures is only an example not restricting the scope
of the present invention.
[0003] Figure 1 shows a basic diagram of the invention in which P
i is the R.F. input power; the block 1 is the electronic ferrite switch; P
1 and P
2 represent the powers being output at two output terminals of said switch, γ 1 and
γ 2 being the corresponding phases; the block 2 represents the monopulse comparator
for the sum bundles ( Σ ) and for the difference bundles (Δ) and finally, the block
3 represents the radiating antenna system.
[0004] Figure 2 represents the block 1 of Figure 1 and is an equivalent circuit diagram
of the electronic ferrite switch located in the waveguide. Here, P
i is the input power fed to the switch; A
1 and A
2 are two hybrid functions interconnected by two ferrite phase shifters A and B. P
1 and P
2 are the R.F. output powers and γ
1 and γ 2 the corresponding phases.
[0005] Figure 3 represents the constructional conception in the R.F. ferrite switch in the
waveguide, in which the par- ticulars indicated by DRIVER are the control circuits
having transistors.
[0006] The electronic switch which allows the fast scanning of the antenna bundle is based
on the monopulse characteristics of the antenna, combining the sum bundle ε with one
of the difference bundles Δ
[0007] The various signal configurations being available at the input terminals of the channels
Σ and A of said monopulse comparator are furnished by the electronic switch the essential
requirements of which being indicated in the following Table I:
Said table indicates the correspondence between the input values and the output
values which can be derived from the following general formulas of the microwave scheme
of Fig. 2:
Wherein E
1, E2 are the output voltages,
for an incoming voltage
[0008] The real radiating system and the monopulse comparator are typical embodiments of
a Cassegrain system with monopulse function. The electronic switch the equivalent
circuit diagram of which being illustrated in Fig. 2 is realized as shown in Fig.
3. A
1 and A
2 are two hybrid junctions interconnected by two ferrite phase shifters. As the switching
over from one status to the other status must be completed within some 10 ps it has
been opted in favour of a latching in guide type phase shifter (see e.g. Ref. No.
1
x) for the relative reading. The phase shifters are controlled by a transistor driver,
which supplies on command the three current couples necessary for the three output
situations.
[0009] As to the materials, use of lithium ferrite for small peak power values and high
average power values is convenient; stabilized garnets for high peak power values
and moderate average power values; the magnetisation levels are chosen according to
the application frequency.
[0010] The real application of such an antenna is in monopulse systems which require fast
sector scanning of such a frequency that no mechanical solution is possible.
[0011] x) Ref. 1 Cattarin G., Parodi M. "Sfasatori a rimanenza in guida d'onda: teoria,
programma di calcolo, alcune applicazioni." Riv. Tec. Selenia, Vol.7, n.l (17 - 26),
1980.
1. System for the fast sectional scanning of a bundle of radar antenna monopulses,
characterized by the use of an electronic switch.
2. System according to claim 1, characterized in that said switch consists of a phase
shifter with ferrite in the remanence, said phase shifter being inserted between two
hybrid connections so that said switch generates output signals having predetermined
phases and has amplitude control.
