Microstrip to ridge waveguide transition

• US 5,095,292 A
• Filed: 08/24/1990
• Issued: 03/10/1992
• Est. Priority Date: 08/24/1990
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Masterton, Brent
• Primary Examiner(s): GENSLER, PAUL L
• Application Number:
  US07/572,511
• Time in Patent Office: 564 Days
• Field of Search: 333/21 R, 333/26, 333/33, 333/34
• US Class Current: 333/26
• CPC Class Codes: H01P 5/107 Hollow-waveguide/strip-line transitions

Abstract

This microstrip to ridge waveguide transition includes a microstrip dipole and a double-ridge waveguide transmission line. The microstrip dipole is centered on the open end of the waveguide and the gap between the dipole and the open end of the waveguide is adjusted for optimum VSWR. The energy is coupled directly and efficiently from the microstrip dipole to the ridges in the waveguide, without the requirement of any direct connections or extra enclosure.

Claims

1. A microstrip transmission line to double ridge waveguide transition circuit, wherein the double ridge waveguide is characterized by an open end and by longitudinally extending ridge elements extending from respective long side walls of the waveguide into the waveguide interior, comprising:

a microstrip circuit, comprising a planar dielectric substrate having a circuit side and a ground plane side, the circuit side being selectively patterned with a conductive layer to define a balun network and a conductor line, the ground plane side being selectively patterned with a conductive layer to define a dipole immediately beneath the balun network and a ground plane surface area; and

and wherein the microstrip circuit is substantially centered on the longitudinal sides of the waveguide adjacent said open end such that a gap exists between the dipole and the waveguide open end, the size of the gap selected for optimum VSWR.

2. The transition circuit of claim 1 wherein the waveguide is further characterized by a flange element disposed at said waveguide open end.

3. The transition circuit of claim 1 wherein said balun and said dipole provide a means for coupling microwave energy between said conductor line and said dipole.

4. The transition circuit of claim 1 wherein said dipole is characterized by a slot impedance, said conductor line is characterized by a first characteristic impedance, said balun network is characterized by a second characteristic impedance, and said circuit further comprises impedance transformation means for transforming from the characteristic impedance of the conductor line to the slot impedance of the dipole.

5. The transition circuit of claim 4 wherein said impedance transformation means comprises a step transformer, wherein the second characteristic impedance of the balun network is greater than the first characteristic impedance of the conductor line, and the slot impedance of the dipole is greater than the second characteristic impedance, said step transformer further comprising a transition conductor line connecting said conductor line to said balun network, said transition line characterized by a transition characteristic impedance, said transition impedance being greater than said first impedance but less than said second impedance.

6. The transition circuit of claim 5 wherein said first characteristic impedance is 50 ohms, said transition impedance is 60 ohms, said second impedance is 70 ohms, and said dipole slot impedance is 100 ohms.

7. A microstrip transmission line to double ridge waveguide transition circuit, wherein the double ridge waveguide is characterized by an open end and by longitudinally extending ridge elements extending from respective long side walls of the waveguide into the waveguide interior, comprising:

a microstrip circuit, comprising a planar dielectric substrate having a circuit side and a ground plane side, the circuit side being selectively patterned with a conductive layer to define a balun network and a conductor line, the ground plane side being selectively patterned with a conductive layer to define a dipole immediately beneath the balun network and a ground plane surface area, wherein said balun and said dipole provide a means for coupling microwave energy between said conductor line and said dipole; and

wherein the microstrip circuit is centered on the longitudinal sides of the waveguide adjacent said open end such that a gap exists between the dipole and the waveguide open end, the size of the gap selected for optimum VSWR.

8. The transition circuit of claim 7 wherein the waveguide is further characterized by a flange element disposed at said waveguide open end.

9. The transition circuit of claim 7 wherein said dipole is characterized by a slot impedance, said conductor line is characterized by a first characteristic impedance, said balun network is characterized by a second characteristic impedance, and said circuit further comprises impedance transformation means for transforming from the characteristic impedance of the conductor line to the slot impedance of the dipole.

10. The transition circuit of claim 9 wherein said impedance transformation means comprises a step transformer, wherein the second characteristic impedance of the balun network is greater than the first characteristic impedance of the conductor line, and the slot impedance of the dipole is greater than the second characteristic impedance, said step transformer further comprising a transition conductor line connecting said conductor line to said balun network, said transition line characterized by a transition characteristic impedance, said transition impedance being greater than said first impedance but less than said second impedance.

11. The transition circuit of claim 10 wherein said first characteristic impedance is 50 ohms, said transition impedance is 60 ohms, said second impedance is 50 ohms, and said dipole slot impedance is 100 ohms.