Array antenna

• US 6,407,719 B1
• Filed: 03/08/2001
• Issued: 06/18/2002
• Est. Priority Date: 07/08/1999
• Status: Expired due to Fees

• Current Assignee: Advanced Telecommunications Research Institute International
• Original Assignee: ATR Adaptive Communications Research Laboratories
• Inventors: Ohira, Takashi, Gyoda, Koichi
• Primary Examiner(s): Ho, Tan
• Application Number:
  US09/786,726
• Time in Patent Office: 467 Days
• Field of Search: 343/815, 343/817, 343/745, 343/749, 343/750, 343/833, 343/834, 343/836, 343/837
• US Class Current: 343/893
• CPC Class Codes: H01Q 19/32 the primary active element being end-fed and elongated
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays
• CPC Class Codes: H01Q 21/20 the units being spaced along or adjacent to a curvilinear path slotted waveguide arrays H01Q21/005; circularly or helically slotted waveguides H01Q21/0062
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/32 Vertical arrangement of element H01Q9/40 takes precedence

Abstract

An array antenna apparatus includes a radiating element (6) for transmitting and receiving radio signals, and at least one parasitic element (7) arranged at a predetermined distance (d) away from the radiating element (6) and incapable of transmitting or receiving radio signals. The parasitic element (7) is connected with a variable-reactance element (23). A controller (100) changes the directivity of the array antenna by changing the reactance X_n of the variable-reactance element (23). The variable-reactance element (23) is a varactor diode (D, D1), for example, and the controller (100) changes the backward bias voltage Vb applied to the variable-reactance diode (D, D1) to change the capacitance of the varactor diode (D, D1), thus changing the directivity of the array antenna. The array antenna has a low-cost and simplified structure compared with the prior art, while facilitating directivity control.

Claims

1. An array antenna apparatus comprising:

a radiating element for transmitting and receiving a radio signal therethrough;

a plurality of parasitic elements each capable of transmitting and receiving any radio signal, said parasitic elements being arranged at a predetermined distance from said radiating element and on a circumference of a predetermined circle around said radiating element;

a plurality of variable-reactance elements connected to said parasitic elements, respectively; and

controlling means for changing directivity of said array antenna apparatus by changing a reactance of each of said variable-reactance elements.

2. The array antenna apparatus as claimed in claim 1,

wherein each of said variable-reactance elements is a varactor diode, and

wherein said controlling means changes a capacitance of each of said varactor diodes by changing a backward bias voltage applied to each of said varactor diodes, thereby changing the directivity of said array antenna apparatus.