Broadband non-directional tap coupler
View Patent ↗A high power, non-directional tap coupler having low loss and expanded bandwidth using a novel airline coaxial line structure. Each of the main and secondary conductors forms a concentric structure of constant dimension over a substantial length inside a metallic housing. The coupled port conductor is connected perpendicularly at the middle point to the secondary conductor. The conductors form a novel structure in which coupling remains relatively constant over a broadband frequency range and main line VSWR remains low. The result is a non-directional tap coupler with a wideband operational frequency, a reduced physical size, and low loss and with good PIM performance.
1. A non-directional tap coupler comprising:
a housing, said housing forming an outer coaxial conductor;
a dielectric within said housing;
a main transmission line defining a main conductor located concentrically within said dielectric; and
a secondary transmission line defining a secondary conductor located concentrically within said housing and surrounding said main conductor, said secondary conductor having two ends and a length therebetween;
a side transmission line defining a side conductor connected to said secondary conductor;
wherein said side conductor connects perpendicular to the length of said secondary conductor; and
wherein said side conductor connects at a point mid-way along the length of said secondary conductor and spaced equally from each of the two ends of said secondary conductor.
2. The coupler of claim 1 , wherein said dielectric comprises air, gas, vacuum or other dielectric or combination thereof.
3. The coupler of claim 1 , wherein said main conductor is essentially of a circular cross-section and connects directly an input port to an output port.
4. The coupler of claim 1 , wherein said secondary conductor is of essentially cylindrical geometry and surrounds said main conductor over a substantial length inside said housing.
5. The coupler of claim 4 , wherein said main conductor and said secondary conductor form a concentric structure which remains constant in size over a substantial length inside said housing.
6. The coupler of claim 5 , wherein said side conductor is substantially perpendicular to said secondary conductor.
7. The coupler of claim 5 , wherein said side conductor is connected to said secondary conductor at a point mid-way along a length of said housing.
8. The coupler of claim 5 , wherein said side conductor forms a coaxial transmission line of essentially 50 ohm characteristic impedance.
9. The coupler of claim 1 , wherein an impedance of said side conductor can be adjusted to compensate a slope of a coupling curve over a broadband frequency range.
10. The coupler of claim 1 , wherein said housing includes:
a concentric hole along its long axis; and a second hole machined perpendicularly to said concentric hole.
11. The coupler of claim 1 , wherein said secondary conductor is in proximity to said main conductor and said housing and influences a characteristic impedance and split ratio of the non-directional tap coupler.