Folded dipole microstrip antenna

• US 5,539,414 A
• Filed: 09/02/1993
• Issued: 07/23/1996
• Est. Priority Date: 09/02/1993
• Status: Expired due to Term

• Current Assignee: Inmarsat Global Limited (Inmarsat PLC)
• Original Assignee: Inmarsat PLC
• Inventors: Keen, Keith M.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/116,243
• Time in Patent Office: 1,055 Days
• Field of Search: 343/700 MS, 343/702, 343/725, 343/793, 343/794, 343/803
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 9/065 Microstrip dipole antennas patch antenna H01Q9/0407
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

A folded dipole microstrip antenna is disclosed herein. The microstrip antenna includes a dielectric substrate for defining a first mounting surface and a second mounting surface substantially parallel thereto. A folded dipole radiative element is mounted on the second mounting surface. The microstrip antenna further includes a microstrip feed line, mounted on the first surface, for exciting the radiative element in response to an excitation signal. In a preferred implementation of the microstrip antenna an excitation signal is applied to the microstrip feed line through a coaxial cable. In such a preferred implementation the folded dipole radiative element includes a continuous dipole arm arranged parallel to first and second dipole arm segments separated by an excitation gap. The feed element is mounted in alignment with the excitation gap and is electrically connected to the continuous dipole arm. The antenna may additionally include a ground plane reflector separated from the folded dipole radiative element by a dielectric spacer for projecting, in a predetermined direction, electromagnetic energy radiated by the folded dipole radiative element. The thickness of the dielectric spacer between the ground plane reflector and the folded dipole radiative element is selected such that the impedance presented by the antenna to the coaxial cable is approximately fifty ohms.

Claims

1. An antenna for a paging receiver, said paging receiver being disposed within a housing, said antenna comprising:

a folded dipole microstrip antenna attached to a first external surface of said housing, said microstrip antenna including a dielectric substrate for defining a first mounting surface and a second mounting surface substantially parallel to said first mounting surface, a folded dipole element mounted on said second mounting surface, said folded dipole element including a continuous arm and first and second dipole arm segments arranged substantially parallel to said continuous arm, a microstrip feed line mounted on said first surface in alignment with an excitation gap defined by ends of said first and second folded dipole arm segments, a reflector for redirecting an electromagnetic energy pattern associated with said folded dipole microstrip antenna away from said housing, wherein said folded dipole element is positioned between said reflector and said microstrip feed line, and means for supplying a received signal from said microstrip feed line to said paging receiver; and

an auxiliary antenna mounted on a second external surface of said housing.

2. The antenna of claim 1, including a dielectric spacer interposed between said reflector and said folded dipole element, wherein thickness of said dielectric spacer is selected such that the impedance presented by said folded dipole microstrip antenna is approximately fifty ohms.