Dual band antenna feed using an embedded waveguide structure

Details Dual band antenna feed using an embedded waveguide structure Dual band antenna feed using an embedded waveguide structure

2002-09-27

2004-03-02

Phan, Tho (Department: 2821)

Communications: radio wave antennas

Antennas

Slot type

C343S772000, C343S786000, C333S135000

Reexamination Certificate

active

06700548

ABSTRACT:

BACKGROUND
1. Technical Field
The present invention relates to dual band antenna feeds for combining two or more different frequency antenna feeds to connect to a single antenna.
2. Related Art
The dual band antenna feeds are usually designed by connecting two waveguide ports carrying signals over two separate frequency bands to a common waveguide structure which connects to an antenna operating over both bands. As illustrated in block diagram form in
FIG. 1
, a conventional antenna feed receives a first high frequency band of signals at input
2
. The second lower frequency band is received at input
4
. A filter
6
, which may be a low pass, band pass, or band stop filter removes higher frequency components from the low frequency input
4
to prevent interference with signals from the high frequency input
2
. Cavity-type filters are used as filter
6
to connect the waveguide ports to the common waveguide and avoid interference between the two frequency bands. Since a filter is a frequency sensitive device, its cost is high due to the tight tolerance and tuning requirements. A common junction
8
combines the signals from ports
2
and
4
to provide an output for an antenna
10
.
SUMMARY
The present invention provides a dual band antenna feed using an embedded waveguide structure made without requiring an added cavity-type filter. The dual band antenna feed of the present invention is made amenable to die-casting.
The dual band antenna feed in accordance with the present invention, referring to
FIG. 2
, includes a Ka and Ku band interface section
22
. The interface section
22
has signals fed from a orthogonal mode transducer (OMT) and power combiner section
20
. The output of the Ka and Ku band interface section
22
is provided to an antenna section
24
.
The Ka and Ku band interface section
22
, referring to
FIGS. 3A-3D
, includes two Ka band vertical polarization waveguide sections
31
and
32
, and a single Ku band waveguide section
34
which carries both vertical and horizontal polarization Ku band signals. The opposing walls
36
-
37
of the Ku band waveguide
34
carrying the vertical polarization Ku band signals are transitioned to step down from an input section
40
to successively smaller dimensioned sections
41
-
44
, and then to step back up in successively larger dimensioned sections
45
-
47
to an output section
48
. The two Ka band sections
31
-
32
are fed into openings in the combined Ka/Ku band section
46
, on opposite sides of the opening for the Ku band transition section
45
. A slightly larger Ka/Ku band section
47
then transitions from section
46
to the output section
48
. The output section
48
provides a combined Ka band vertical and Ku band horizontal and vertical signals. The output section
48
connects to the separate antenna section (
24
). With the Ka-band waveguides
31
-
32
having ports
56
-
57
facing the antenna port for radiation on opposite sides of the Ku-band section
45
port, sufficient isolation will be provided between the Ka and Ku band signals without requiring an additional filter.
The OMT and power combiner section
20
can have components as shown in
FIGS. 4A-4D
. The OMT
90
is a conventional device with separate Ku band vertical and horizontal polarization inputs
12
and
14
which combines the inputs to produce a single output carrying both the vertical and horizontal polarization Ku band signals. The power combiner has a first input (
16
) for receiving the Ka band vertical polarization signal, and functions to split the input into two separate signals provided in two separate Ka band vertical polarization waveguides
81
-
82
.
The Ka and Ku band interface section
22
can be manufactured from a single block of stock metal. The stock metal block is first cut into two halves, and the Ka band waveguides are machined into the halves. The two halves are then each cut in half to form a total of four quarter sections. The Ku band waveguide is then machined into the quarter sections, and the quarter sections are reassembled to form the completed interface section
22
. The quarter sections can be used to form molds which are then used for die casting to enable rapid manufacturing of multiple interface sections
22
.
In one embodiment, the antenna feed can include a dielectric insert as shown in
FIGS. 8A-8C
. The dielectric insert includes Ka band inserts
110
and
111
which insert into Ka band sections
31
and
32
to improve matching between the Ka band sections
31
and
32
and combined Ka/Ku band section
46
. A notch
114
is further included to improve the match between the Ku band section
45
and combined Ka/Ku band section
46
. The insert has a rectangular portion
106
which transitions into a tapered conical section
108
which extends into the antenna portion
24
of the antenna feed.


REFERENCES:
patent: 4491810 (1985-01-01), Saad
patent: 4912436 (1990-03-01), Alford et al.
patent: 5859620 (1999-01-01), Skinner et al.
patent: 6046702 (2000-04-01), Curtis et al.
patent: 2002/0175875 (2002-11-01), Verstraeten

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