Transmitter with improved sensitivity and shielding
First Claim
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1. A magnetic field transmitter configured to generate a time varying magnetic field in response to a time varying input signal, the magnetic field transmitter comprising:
- a) a transmitter coil winding including a lower surface, a bundle of continuous conductor loops, a number of turns N, a coil winding resistance R, an effective coil radius Re, a coil winding inductance L, a conductor having a cross-sectional area A, a total length l, and a resistivity ρ
, the bundle of continuous conductor loops having a center, an inner perimeter, and an outer perimeter, the inner perimeter and the outer perimeter separated by a distance; and
b) a backing plate including magnetic material having an upper surface, a lower surface, and an outer perimeter, the lower surface of the backing plate attached in close proximity to a lower surface of the transmitter coil winding, the outer perimeter approximately coincident with the outer perimeter of the transmitter coil winding,wherein the coil winding resistance and the coil winding inductance produce a break frequency for the transmitter coil winding of between 20 Hz and 2000 Hz, wherein the break frequency is defined by formula fb=R/(2π
L), the coil winding resistance R is defined by formula R=ρ
l/A, and the coil winding inductance L is defined by formula L=N2(uoπ
Re)/2, and wherein constant uo is the permeability of free space.
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Abstract
A magnetic field transmitter, especially a transmitter used in conjunction with wireless communications earplugs. In one embodiment, a plate of magnetic material is used behind a coil of electrical conductor to improve the efficiency of the transmitter and to provide electrical and magnetic shielding. The specific dimensions and characteristics of the preferred embodiment of the transmitter described herein provide for efficient wireless communications.
63 Citations
18 Claims
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1. A magnetic field transmitter configured to generate a time varying magnetic field in response to a time varying input signal, the magnetic field transmitter comprising:
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a) a transmitter coil winding including a lower surface, a bundle of continuous conductor loops, a number of turns N, a coil winding resistance R, an effective coil radius Re, a coil winding inductance L, a conductor having a cross-sectional area A, a total length l, and a resistivity ρ
, the bundle of continuous conductor loops having a center, an inner perimeter, and an outer perimeter, the inner perimeter and the outer perimeter separated by a distance; andb) a backing plate including magnetic material having an upper surface, a lower surface, and an outer perimeter, the lower surface of the backing plate attached in close proximity to a lower surface of the transmitter coil winding, the outer perimeter approximately coincident with the outer perimeter of the transmitter coil winding, wherein the coil winding resistance and the coil winding inductance produce a break frequency for the transmitter coil winding of between 20 Hz and 2000 Hz, wherein the break frequency is defined by formula fb=R/(2π
L), the coil winding resistance R is defined by formula R=ρ
l/A, and the coil winding inductance L is defined by formula L=N2(uoπ
Re)/2, and wherein constant uo is the permeability of free space. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A magnetic field transmitter configured to generate a time varying magnetic field in response to a time varying input signal, the magnetic field transmitter comprising:
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a) a transmitter coil winding including a lower surface, a bundle of continuous conductor loops, a number of turns N, a coil winding resistance R, an effective coil radius Re, a coil winding inductance L, a conductor having a cross-sectional area A, a total length l, and a resistivity ρ
, wherein the bundle has an inner perimeter and an outer perimeter seperated by a distance; andb) a backing plate comprising magnetic material having an upper surface, a lower surface, and an outer perimeter, the lower surface of the backing plate attached in close proximity to the lower surface of the transmitter coil winding, an outer perimeter approximately coincident with the outer perimeter of the transmitter coil winding, wherein the backing plate covers the lower surface of the transmitter coil winding, and the upper surface of the transmitter coil winding is at least partly uncovered by the backing plate, wherein the coil winding resistance and the coil winding inductance produce a break frequency for the transmitter coil winding of between 20 Hz and 2000 Hz, wherein the break frequency is defined by formula fb=R/(2π
L), the coil winding resistance R is defined by formula R=ρ
l/A, and the coil winding inductance L is defined by formula L=N2(uoπ
Re)/2, and wherein constant uo is the permeability of free space. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification