Dipole antenna arrangement for radio with separate speaker-microphone assembly

Claim 2

In a speaker microphone assembly adapted to be held in the hand and for use with a portable radio unit including receiving and transmitting equipment for receiving and transmitting signals, the combination of, a housing having top, bottom and side walls, an elongated antenna element secured to said top wall, said antenna element forming one half of a dipole antenna for radiating signals coupled from said transmitting equipment and coupling radiated signals to said receiving equipment, a cable for coupling the portable unit to said housing, said cable containing a coaxial transmission line having an inner conductor and an outer conductor, said outer conductor terminating at a first point in said housing, circuit means coupling said inner conductor to said antenna element, a second outer conductor surrounding said coaxial transmission line and extending for a predetermined length from said first point along said transmission line, said second outer conductor being connected to said outer conductor of said transmission line at said first point and both conductors forming the other half of said dipole antenna.

Claim 3

In a speaker microphone assembly adapted to be held in the hand and for use with a portable radio unit including receiving and transmitting equipment for receiving and transmitting signals, the combination of, a housing having top, bottom and side walls, an elongated antenna element secured to said top wall, said antenna element forming one half of a dipole antenna for radiating signals coupled from said transmitting equipment and coupling radiated signals to said receiving equipment, a cable for coupling the portable unit to said housing, said cable containing a coaxial transmission line having an inner conductor and an outer conductor, said outer conductor terminating at a first point in said housing, circuit means coupling said inner conductor to said antenna element, a second outer conductor surrounding said coaxial transmission line and extending for a predetermined length from said first point along said transmission line, said second outer conductor being connected to said outer conductor of said transmission line at said first point and both conductors forming the other half of said dipole antenna.

Claim 4

In a speaker microphone assembly adapted to be held in the hand and for use with a portable radio unit including receiving and transmitting equipment for receiving and transmitting signals, the combination of, a housing having top, bottom and side walls, an elongated antenna element secured to said top wall, said antenna element forming one half of a dipole antenna for radiating signals coupled from said transmitting equipment and coupling radiated signals to said receiving equipment, a cable for coupling the portable unit to said housing, said cable containing a coaxial transmission line having an inner conductor and an outer conductor, said outer conductor terminating at a first point in said housing, circuit means coupling said inner conductor to said antenna element, a second outer conductor surrounding said coaxial transmission line and extending for a predetermined length from said first point along said transmission line, said second outer conductor being connected to said outer conductor of said transmission line at said first point and both conductors forming the other half of said dipole antenna.

Claim 5

The assembly of claim 1 wherein said dipole antenna is resonant at a particular frequency, said antenna element and said other half of said dipole antenna each having an electrical length substantially equal to a quarter wavelength at the resonant frequency of said dipole antenna.

Claim 6

The assembly of claim 2 wherein said antenna element includes a conductive element having first and second ends, and mounting means secured to one of said ends and adapted to engage said circuit means in said assembly.

Claim 7

The assembly of claim 3 wherein said conductive element is formed into a helix for providing a quarter wavelength helical antenna element. 5. The assembly of claim 4 wherein said antenna element includes a tube of nonconductive material surrounding said helical element, said nonconductive material acting to insulate said helical element and maintain the same in a semi-rigid condition.

Claim 8

The assembly of claim 4 wherein said circuit means is a connector, said connector being secured to a wall of said housing and having said center conductor coupled thereto, said connector adapted to mate with said antenna element mounting means for mounting said antenna element to said assembly housing.

Claim 9

The assembly of claim 6 wherein said cable further includes insulating means surrounding said outer conductor of said coaxial transmission line and between said outer conductor and said second conductor, said insulating means providing an insulated separation therebetween.

Claim 10

The assembly of claim 7 wherein said portable unit includes a power source having first and second terminals, one of said terminals forming a reference potential, said reference potential being coupled to said transmission line outer conductor.

Claim 11

The assembly of claim 8 further including speaker means, microphone means and unit actuating means mounted in said assembly housing, conductor means coupling said speaker means, microphone means and actuating means to the portable unit for providing electrical connections therebetween, said speaker means including a speaker frame, said speaker means, said speaker frame and said microphone means being coupled to said first point to provide a reference potential thereat.

Claim 12

The assembly of claim 9 wherein said outer conductor of said transmission line and said second outer conductor are formed from braided wire conductors.

Claim 13

The assembly of claim 9 wherein said second outer conductor is a conductive material secured to said housing walls and coupled to said first point, said housing further including an aperture in said bottom wall, said cable extending through said aperture and said conductive material being isolated from said aperture.

Claim 14

The assembly of claim 11 wherein said conductive material is a conductive paint applied to said housing inner walls and having a predetermined thickness.

Claim 15

The assembly of claim 12 wherein said conductive paint is a silver conductive paint.

Claim 16

The assembly of claim 13 wherein said predetermined thickness is at least 1 mil.

Claim 17

A speaker microphone assembly for use with a portable radio unit including receiving and transmitting equipment for receiving and transmitting signals, said portable radio unit having a power source therein with one terminal thereof being a reference potential, said speaker microphone assembly including in combination, a housing having top, bottom and side walls adapted to be held in a user''s hand, said bottom wall having an aperture therethrough, transducer means mounted in said assembly housing, a helical antenna element detachably secured to said housing, said antenna element forming one portion of a dipole antenna for radiating signals coupled from said transmitting equipment and coupling radiated signals to said receiving equipment, a connector secured to said housing for detachably securing said helical antenna element, a cable for coupling the portable unit to said housing, said cable containing a plurality of conductors coupling said equipment to said transducer means for providing electrical connections therebetween, and a coaxial transmission line having an inner conductor and an outer conductor, said inner and outer conductor of said coaxial transmission line being connected to said connector, said inner conductor coupling said helical antenna element to said equipment, said outer conductor forming a low impedance point at said connector, said housing further including a conductive material applied to said housing inner walls and connected to said low impedance point, said conductive material being isolated from said aperture in said bottom wall and forming a second outer conductor for surrounding said coaxial Transmission line, said transmission line outer conductor and said second outer conductor together forming the other portion of said dipole antenna.

Claim 18

A speaker microphone assembly for use with a portable radio unit including receiving and transmitting equipment for receiving and transmitting signals, said portable radio unit having a power source therein with one terminal thereof being a reference potential, said speaker microphone assembly including in combination, a housing having top, bottom and side walls adapted to be held in a user''s hand, said bottom wall having an aperture therethrough, transducer means mounted in said assembly housing, a helical antenna element detachably secured to said housing, said antenna element forming one portion of a dipole antenna for radiating signals coupled from said transmitting equipment and coupling radiated signals to said receiving equipment, a connector secured to said housing for detachably securing said helical antenna element, a cable for coupling the portable unit to said housing, said cable containing a plurality of conductors coupling said equipment to said transducer means for providing electrical connections therebetween, and a coaxial transmission line having an inner conductor and an outer conductor, said inner and outer conductor of said coaxial transmission line being connected to said connector, said inner conductor coupling said helical antenna element to said equipment, said outer conductor forming a low impedance point at said connector, said housing further including a conductive material applied to said housing inner walls and connected to said low impedance point, said conductive material being isolated from said aperture in said bottom wall and forming a second outer conductor for surrounding said coaxial Transmission line, said transmission line outer conductor and said second outer conductor together forming the other portion of said dipole antenna.