Mobile communications antenna

A mobile communications antenna assembly for use over a selected band of frequencies in the VHF and UHF ranges, comprising:

• a radiating element having first, second and third, collinear radiating sections, said first and second sections each having an effective electrical length substantially equal to five-eighths of the center wavelength of the selected frequency band and said third section having an effective electrical length substantially equal to one-quarter of the center wavelength of the selected frequency band;
• first phase inductance means electrically connecting said first and second sections for maintaining a predetermined phase relationship between electrical signals radiating from said first and second sections;
• second phase inductance means electrically connecting said second and third sections for maintaining a predetermined phase relationship between electrical signals radiating from said second and third sections;
• a base member electrically connected adjacent to a base end of said third section for mounting said radiating element to a surface so that said third section base end is elevated above said surface;
• impedance matching means comprising a tuned circuit selectively tunable to the nominal resonant frequency of said radiating element and electrically connected thereto, said impedance matching means displaying an impedance which varies between a first impedance value at said connection to said radiating element, said first value being substantially equal to the impedance at said base end, and a second impedance value that is at least several orders of magnitude less than said first impedance value;
• and
• connecting means for coupling transmission line means to said impedance matching means at a point where the impedance of said impedance matching means is substantially equal to the impedance of the transmission line means.

A mobile communications antenna assembly adapted for mounting on a vehicle and adapted for use over a selected band of frequencies in the VHF and UHF ranges, comprising:

• a radiating element having first, second and third, collinear radiating sections, said first and second sections each having an electrical length substantially equal to five-eighths of the center wavelength of the selected frequency band, and said third section having an electrical length substantially equal to one-quarter of the center wavelength of the selected frequency band, said third section further adapted to have a radiating surface area substantially greater than the radiating surface areas of said first and second sections by having a diameter substantially greater than the diameter of each of said first and second sections, so as to increase the radiating surface area of said third section in comparison to the radiating surface areas of said first and second sections;
• first phase inductance means connecting said first and second sections for maintaining a predetermined phase relationship between electrical signals radiating from said first and second sections including an open air helical coil inductor formed from said radiating element;
• second phase inductance means connecting said second and third sections for maintaining a predetermined phase relationship between electrical signals radiating from said second and third sections, said third section having a base end;
• said third section further having a radiating surface area that is substantially greater than the radiating surface areas of each of said first and second radiating sections;
• a base member, having a first conductive coupling member electrically connected to and disposed adjacent said third section base end, for mounting said radiating element to a first side of a non-conductive body portion of the vehicle so that said third section base end is elevated above the surface of said body portion and including a first adjusting means connected between said third section base end and said first coupling member to permit user adjustment to align said radiating element to be generally vertical with regard to the earth's surface;
• a second conductive coupling member mounted on a second, opposite side of said non-conductive body portion in substantial juxtaposition with said first conductive coupling member defining, with said non-conductive body portion, a coupling capacitor having a fixed plate surface area at the third section base end and located adjacent a current node thereof;
• impedance matching means comprising a user adjustable capacitance member and a series tuned circuit selectively tunable to the nominal resonant frequency of said radiating element and electrically connected to said second electrically conductive coupling member in the immediate proximity thereof to resonate in conjunction with said radiating element, said impedance matching means displaying an impedance which varies between a first impedance value at said connection to said second conductive coupling member which is substantially equal to the impedance at said third section base end and a second impedance value that is at least several orders of magnitude less than said first impedance value;
• transmission line means for connection between the antenna assembly and a radio communications unit, said transmission line means having an impedance that is orders of magnitude less than the impedance of the antenna assembly at said third section base end;
• and
• coupling means adapted to connect said transmission line means to said impedance matching means at a point where the impedance of said impedance matching means is substantially equal to the impedance of said transmission line means.

A mobile communications antenna assembly adapted for mounting on a vehicle and adapted for use over a selected band of frequencies in the VHF and UHF ranges, comprising:

• a radiating element having first, second and third, collinear radiating sections, said first and second sections each having an electrical length substantially equal to five-eighths of the center wavelength of the selected frequency band and said third section having an electrical length substantially equal to one-quarter of the center wavelength of the selected frequency band;
• first phase inductance means connecting said first and second sections for maintaining a predetermined phase relationship between electrical signals radiating from said first and second sections;
• second phase inductance means connecting said second and third sections for maintaining a predetermined phase relationship between electrical signals radiating from said second and third sections, said third section having a base end;
• said third section further having a radiating surface area that is substantially greater than the radiating surface areas of each of said first and second radiating sections;
• a base member, having a first conductive coupling member electrically connected to and disposed adjacent said third section base end, for mounting said radiating element to a first side of a non-conductive body portion of the vehicle so that said third section base end is elevated above the surface of said body portion;
• a second conductive coupling member mounted on a second, opposite side of said non-conductive body portion in substantial juxtaposition with said first conductive coupling member defining, with said non-conductive body portion, a coupling capacitor having a fixed plate surface area at the third section base end and located adjacent a current node thereof;
• impedance matching means comprising a tuned circuit selectively tunable to the nominal resonant frequency of said radiating element and electrically connected to said second electrically conductive coupling member in the immediate proximity thereof to resonate in conjunction with said radiating element, said impedance matching means displaying an impedance which varies between a first impedance value at said connection to said second conductive coupling member which is substantially equal to the impedance at said third section base end and a second impedance value that is at least several orders of magnitude less than said first impedance value;
• and
• coupling means adapted to connect transmission line means to said impedance matching means at a point where the impedance of said impedance matching means is substantially equal to the impedance of the transmission line means.

A mobile communications antenna assembly for use over a selected band of frequencies in the VHF and UHF ranges, comprising:

• a radiating element having first, second and third, collinear radiating sections, said first and second sections each having an effective electrical length substantially equal to at least one-half of the center wavelength of the selected frequency band and said third section having an effective electrical length substantially equal to one-quarter of the center wavelength of the selected frequency band, said third section further adapted to have a radiating surface area substantially greater than the radiating surface areas of said first and second sections by having a diameter substantially greater than the diameter of each of said first and second sections, so as to increase the radiating surface area of said third section in comparison to the radiating surface areas of said first and second sections;
• first phase inductance means electrically connecting said first and second sections for maintaining a predetermined phase relationship between electrical signals radiating from said first and second sections including an open air helical coil inductor formed from said radiating element;
• second phase inductance means electrically connecting said second and third sections for maintaining a predetermined phase relationship between electrical signals radiating from said second and third sections including a helical coil inductor formed from said radiating element;
• a base member electrically connected adjacent to a base end of said third section for mounting said radiating element to a non-conducting surface of a vehicle, so that said third second base end is elevated above said surface;
• a first plate member connected to said third section base end including user adjustment means for positioning said radiating element in a generally vertical configuration with regard to the earth's surface;
• impedance matching means comprising a user adjustable capacitance member and a series series tuned circuit which is selectively tunable to the nominal resonant frequency of said radiating element and electrically connected thereto, said impedance matching means displaying an impedance which varies between a first impedance value at said connection to said radiating element, said first value being substantially equal to the impedance at said base end, and a second impedance value that is at least several orders of magnitude less than said first impedance value;
• transmission line means for communicating between the antenna assembly and a radio communications unit, said transmission line means having an impedance that is orders of magnitude less than the impedance of the antenna assembly at said base end of said third section;
• and
• connecting means for coupling said transmission line means to said impedance matching means at a point where the impedance of said impedance matching means is substantially equal to the impedance of the transmission line means.

A mobile communications antenna assembly for use over a selected band of frequencies in the VHF and UHF ranges, comprising:

• a radiating element having first, second and third, collinear radiating sections, said first and second sections each having an effective length substantially equal to one-half of the center wavelength of the selected frequency band and said third section having an effective electrical length substantially equal to one-quarter of the center wavelength of the selected frequency band;
• first phase inductance means electrically connecting said first and second sections for maintaining a predetermined phase relationship between electrical signals radiating from said first and second sections;
• second phase inductance means electrically connecting said second and third sections for maintaining a predetermined phase relationship between electrical signals radiating from said second and third sections;
• a base member electrically connected adjacent to a base end of said third section for mounting said radiating element to a surface so that said third section base end is elevated above said surface;
• impedance matching means comprising a tuned circuit selectively tunable to the nominal resonant frequency of said radiating element and electrically connected thereto, said impedance matching means displaying an impedance which varies between a first impedance value at said connected to said radiating element, said first value being substantially equal to the impedance at said base end, and a second impedance value that is at least several orders of magnitude less than said first impedance value;
• and
• connecting means for coupling transmission line means to said impedance matching means at a point where the impedance of said impedance matching means is substantially equal to the impedance of the transmission line means.

A mobile communications antenna assembly for use over a selected band of frequencies within the VHF and UHF ranges, comprising:

• a radiating element having first, second and third collinear radiating sections, each of said sections having an effective electrical length substantially equal to at least one-quarter of the center wavelength of the selected frequency band;
• first phase inductance means electrically connected to said first and second radiating sections, and second phase inductance means electrically connected to said second and third radiating sections respectively, for maintaining a predetermined phase relationship between electrical signals radiating from each of said paired radiating sections;
• said second radiating section having a first portion and a second portion including a hollow, generally frusto-conically shaped radiating member attached proximate said second phase inductance means, and having an opening at its base end with sufficient diameter to receive and overlap, at least partially, a portion of said third radiating section, and electrically connected to said third radiating section only through said second phase inductance means;
• and,
• said third radiating section further adapted to have a radiating surface area substantially greater than the radiating surface areas of said first and second sections by having a diameter substantially greater than that of said first section and said second section first portion so as to increase the radiating surface area of said third section in comparison to the radiating surface areas of said first and second sections.

A mobile communications antenna assembly for use over a selected band of frequencies in the VHF and UHF ranges, comprising:

• a first hollow, tubular radiating member having an effective electrical length substantially equal to at least one-quarter of the center wavelength of the selected frequency band;
• a first phase inductance means for maintaining a predetermined phase relationship of electrical signals in said first radiating member electrically connected to and received, at least partially, in the interior of said first hollow, tubular radiating member;
• a second radiating section fabricated from a single wire conductor and having effective electrical length substantially equal to at least one-half of the center wavelength of the selected frequency band and electrically connected collinearly to said first phase inductance means;
• a cap member attached to said second radiating section proximate said first phase inductance means and adapted to overlap, at least partially, a portion of said first radiating member for sealing said first phase inductance means within the interior of said first hollow tubular radiating member;
• a second phase inductance means for maintaining a predetermined phase relationship of electrical signals in said second radiating member, electrically connected collinearly to said second radiating member;
• and
• a third radiating section fabricated from a single wire conductor and having effective electrical length substantially equal to at least one-half of the center wavelength of the selected frequency band and electrically connected collinearly to said second phase inductance means.