Communications: radio wave antennas – Antennas – Slot type
Reexamination Certificate
1999-08-27
2001-06-12
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Slot type
C343S767000
Reexamination Certificate
active
06246377
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to printed radiating antennas. More particularly, the present invention relates to a novel antenna structure comprising two separate wideband notch regions formed on one coplanar substrate.
2. The Prior Art
The use of antennas has become commonplace in electronic devices such as cellular phones, radios, television, and computer networks. An antenna is comprised of a system of wires or other conductors used to transmit or receive radio or other electromagnetic waves.
Many antennas are highly resonant, operating over bandwidths of only a few percent. Such “tuned,” narrow-bandwidth antennas may be entirely satisfactory or even desirable for single-frequency or narrowband applications. However, in many situations wider bandwidths are desirable. Such an antenna capable of functioning satisfactorily over a wide range of frequencies is generally referred to as a broadband antenna.
One of the well-known prior art antennas is the exponential notch antenna. The exponential notch takes the form of a substrate such as a circuit board having a conductive surface disposed thereon. An exponential notch is removed from the conductive surface and the antenna is coupled to a 50-&OHgr; strip line on an opposing surface of the board. This small broadband antenna is well adapted for printed-circuit fabrication.
Another prior art antenna is disclosed in U.S. Pat. No. 4,853,704 issued to Diaz et al. It has a wide bandwidth and one antenna input port. The Diaz et al. antenna comprises a strip conductor, a ground plane separated from and lying parallel to the strip conductor, the grouped plane having a slot therein, the slot extending transverse to the strip conductor, a conductive planar element positioned across the slot and orthogonal to the ground plane, the conductive planar element having curved surfaces extending upwardly and outwardly from the slot. The strip conductor and the ground provided with a slot are generally composed of a dielectric material.
U.S. Pat. No. 5,519,408 issued to Schnetzer discloses a printed tapered notch (coplanar) antenna which has wide bandwidths and one antenna input. The antenna includes a radiating tapered notch and is fed by a section of slotline, which in turn is fed by a coplanar waveguide. The transition from the unbalanced coplanar waveguide to the balanced slotline is accomplished by an infinite balun, where the center conductor of coplanar waveguide terminates on the slotline conductor opposite the ground conductor of the coplanar waveguide. One slot of the coplaner waveguide becomes the feeding slotline for the notch, and the other slot terminates in a slotline open circuit.
U.S. Pat. No. 5,264,860 issued to Quan discloses a flared notch radiator antenna having separate isolated transmit and receive ports. The assembly includes a flared notch radiating element, a transmit port and a receive port, and a signal duplexer is integrated into the assembly for coupling the radiating element to the respective transmit and receive ports. The duplexer provides for coupling the transmit port to the radiating element so that transmit signals are radiated into free space. The duplexer is described as being capable of coupling the radiating element to the receive port so that signals received at the radiating element are coupled to the receive port, and for isolating the transmit port from the receive port. In its preferred embodiment the duplexer is described as a four port circulator, with a first port connected to the transmit port, a second port connected to the balun which couples energy into and out of the flared notch radiator, a third port connected to the receive port, and a fourth port connected to a balanced load. In this manner, the transmit port is isolated from the receive port, and vice versa.
United Kingdom Patent Application No. 2,281,662 issued to Alcatel Espace discloses a printed coplanar notch (single port) with an integrated amplifier. The antenna includes a slot line having an end section with a flared profile to form a Vivaldi antenna. The slot line has an open circuit termination which provides impedance matching so that separate matching circuit is not required between the antenna and an associated low noise amplifier. A series of antennas are disposed in an array to enable localization to be performed by interferometric techniques.
These aforementioned approaches and examples appear to resolve some of the problems associated with transmitting and receiving signals over the broadband frequency range. Additionally, the prior art teaches the use of a plurality of broadband antennas for transmitting and receiving radio frequency energy.
However, none of these inventions teaches a coplanar antenna with two wideband notch radiators operating in a transmit/receive mode which allows separate paths for the transmit and receive antennas so that the transceiver does not require a selection switch.
Accordingly it is an object of the invention to provide a broadband antenna design which is lightweight, simple and compact in design, and inexpensive to manufacture.
Another object of the invention is to provide a single transmit and receive antenna that avoids the need to switch between transmit/receive functions.
It is a further object to provide a broadband antenna having a plurality of geometric configurations to generate an omnidirectional or directional radiation pattern.
Another object of the invention is to provide an antenna that can be used for wireless communication systems.
Other objects, together with the foregoing are attained in the exercise of the invention in the following description and resulting in the embodiments described with respect to the accompanying drawings.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is a simplified coplanar antenna having at least two notch radiators operating in a transmit/receive mode which produce radiation characteristics that are omnidirectional or directional depending on the size of the antenna.
The omnidirectional and directional antenna designs of the present invention operate over a specified frequency range. The specified operating frequency range is determined by the relative size and shape of the notched regions performing the receiving and transmitting functions of the antenna.
The present invention comprises a transmitting and receiving antenna having separate wideband notch regions on one coplanar substrate. The coplanar substrate has a first face and a second face. The first face has a first wideband notch region for transmission and a second wideband notch region for reception. An optional stop notch may be added to improve the isolation between the transmitting and receiving regions. The second face of the coplanar substrate has two conducting lines acting as transmission lines which are coupled to an integrated circuit. By way of example and not of limitation, such a integrated circuit may include an application specific integrated circuit (ASIC) resident on the second face of the coplanar substrate. The ASIC generates or receives modulated signals which are transmitted or received by the antenna.
According to the present invention, each conducting line or radial stub is electrically coupled to the respective wideband notch regions on the first face of the substrate. The electrical coupling between the transmission lines and the notched regions may be performed by resistively coupling the transmission lines and the notched regions using a plated via-hole technique. However, in the preferred embodiment, the conductive line or radial stub is capacitively coupled to the notched regions to reduce errors, complexity, and costs.
In operation, a signal is radiated from one notched region of the broadband antenna of the present invention. The signal propagates through the edges of the notched region producing a beam polarized in the direction of the edges. A second notched region comprises the receiving antenna.
The antenna of the present invention can be made omnidirectional by fabricating an antenna with
Aiello G. Roberto
Foster Patricia R.
Fantasma Networks, Inc.
Sierra Patent Group Ltd.
Tran Thuy Vinh
Wong Don
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