Array antenna generating circularly polarized waves with a plurality of microstrip antennas

• US 5,287,116 A
• Filed: 05/29/1992
• Issued: 02/15/1994
• Est. Priority Date: 05/30/1991
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sawada, Hisashi, Iwasaki, Hisao
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): BROWN, PETER T
• Application Number:
  US07/891,163
• Time in Patent Office: 627 Days
• Field of Search: 343/700 MS File, 343/853, 343/857, 343/858, 333/24 R
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 21/065 Patch antenna array
• CPC Class Codes: H01Q 5/35 using two or more simultaneously fed points
• CPC Class Codes: H01Q 9/0442 with particular tuning means
• CPC Class Codes: H01Q 9/0457 electromagnetically coupled to the feed line

Abstract

A microstrip antenna is disclosed which comprises a ground conductor plate and a patch opposed to the ground conductor plate with a particular distance, a transmission feed line and a reception feed line being disposed between the ground conductor plate and the patch. Signals are fed from these feed lines to the patch by electromagnetic coupling. The angle made by the extended lines of these feed lines is nearly 90°. When four patches are disposed in a square arrangement, the transmission feed line feeds signals in directions of first lines which pass through the center point of each patch in such a way that the directions are line-symmetrical with respect to a horizontal line and a vertical line which pass through the center point of the square arrangement. On the other hand, the reception feed line feeds signals in the directions of second lines which pass through the center point of each patch and intersect with each first line at right angle. As a result, the mutual coupling between transmission and reception can be suppressed to a low level. In addition, when the transmission feed line is radiately connected from the center point of the square arrangement to each patch, the length thereof can be reduced, thereby decreasing the transmission loss.

Claims

1. A microstrip antenna, comprising:

a substrate having a particular permittivity;

an even number of antenna elements disposed on said substrate in a radial pattern from a central point such that a center portion of each of the antenna elements is positioned on a radial line passing through the central point;

an even number of first feed lines for successively feeding a first high frequency signal to the antenna elements in order of a first rotational direction about the central point, each of the first feed lines extending along the radial lines to intersect with each of the antenna elements respectively; and

an even number of second feed lines for successively feeding a second high frequency signal to the antenna elements in order of a second rotational direction about the central point, the frequency of the second high frequency signal being different from the frequency of the first high frequency signal, the second rotational direction being in reverse to the first rotational direction, each of the second feed lines extend along a line which is perpendicular to the respective radial lines along which the first feed lines extend, each of the second feed lines being line-symmetrical with respect to a straight line which extends through the central point to a midpoint between two adjacent antenna elements.

2. The microstrip antenna according to claim 1 wherein said first feed lines are transmission feed means for feeding a signal to said antenna elements, said second feed lines are reception feed means for guiding a radio frequency signal induced in said antenna elements.

3. The microstrip antenna according to claim 1 wherein said first feed lines are reception feed means for guiding a radio frequency signal induced in said antenna elements, said second feed lines are transmission feed means for feeding a signal to said antenna elements.

4. The microstrip antenna according to claim 1 wherein said first feed lines and said second feed lines have phase delay means for delaying the phases of signals by 90°

and feeding the signals to said antenna elements, respectively.

5. The microstrip antenna according to claim 1 wherein said first feed lines and said second feed lines feed signals to said antenna elements by electromagnetic coupling.