Communications: radio wave antennas – Antennas – Antenna components
Reexamination Certificate
2001-07-13
2002-08-13
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna components
C343S7000MS, C343S756000
Reexamination Certificate
active
06433756
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to thin or low-profile antennas, and particularly to thin or low-profile antennas having good radiation capacities for receiving and/or sending radio frequency signals at a low angle to the major surface of the antenna.
BACKGROUND AND FEATURES OF THE INVENTION AND CROSS REFERENCE TO RELATED APPLICATIONS
The standard telecommunications (e.g. cellular telephone) antenna seen on the exteriors of automobiles today is a vertical antenna. This antenna presents a number of difficulties. First, it is not suitable for use with satellite communication services including current GPS and direct satellite broadcast services since those services may rely on satellites positioned most or less overhead where the vertical antenna lacks sensitivity. Second, future telecommunication systems will put more demands upon antennas. If vertical antennas were used to try to meet this demand, a number of antennas would be installed on the roof of a vehicle and as the desired performance of the antennas increased so would their number—a forest of antennas could result. Third, these vertical antennas are (i) unsightly, (ii) subject to increased risk of breakage and damage and (iii) non-aerodynamic, particularly as their numbers increase. Forth, vertical antennas are effective only with vertically polarized radio frequency signals. A modern antenna needs to be able to handle both vertical and non-vertical emissions—satellite emissions are apt to be circularly polarized.
The ideal antenna for a vehicle, such as an automobile, would be an antenna which:
(1) has a very small profile (so that it does not protrude in any significant way from the surface of the vehicle in which it is mounted);
(2) can handle radio frequency signals of different polarizations; and
(3) has both acceptable low angle (to the major surface of the antenna) efficiency and at the same time can handle communications with satellites positioned overhead.
The present invention has advantages for producing low-angle radiation from a low-profile antenna. The antenna may be horizontally mounted and, indeed, it may be conveniently mounted on or in the exterior surfaces of vehicles such as automobiles, trucks, trains and aircraft. With the future introduction of high-speed third-generation wireless data communication systems, such as third generation cellular systems, there will be a need for antennas that have appreciable gain near the horizon, since these systems will be primarily involving communications with ground base stations. Furthermore, for satellite-based direct broadcast radio and two-way communication systems there is also a need for the antenna to have significant gain at angles as low as 30 degrees from the horizon or lower as well as have the capability to serve satellites which are positioned overhead.
For mobile users in vehicles, one possible location for such an antenna is in the roof of the vehicle over the occupant area, which provides a broad area that can accommodate multiple antennas. However this can involve radiating at a low angle across a large metal surface, which is difficult particularly for horizontal or circular polarizations. Historically, the only way to produce significant antenna gain near the horizon is to provide an antenna with significant vertical height—usually a large fraction of a wavelength depending on the antenna design. The use of a tall vertical antenna reduces the aerodynamic performance of the vehicle and is often quite undesirable for aesthetic styling purposes.
The present invention provides a good alternative, because it provides a specific method for producing low-angle radiation for horizontal, vertical, and circular polarizations while at the same time maintaining a low-profile shape. Antennas using this technique typically have a vertical height of much less than one-quarter wavelength.
The prior art includes the following patent application owned by UCLA: D. Sievenpiper and E. Yablonovitch, “Circuit and Method for Eliminating Surface Currents on Metals” U.S. provisional patent application serial No. 60/079953, filed Mar. 30, 1998 and corresponding PCT application PCT/US99/06884, published as WO99/50929 on Oct. 7, 1999, the disclosures of which are hereby incorporated herein by reference.
Related patent applications include the following U.S. Patent Applications all of which are hereby incorporated hereby by reference:
1) D. Sievenpiper, R. Harvey, G. Tangonan, R. Y. Loo, J. Schaffner, “A Tunable Impedance Surface”, U.S. Ser. No. 09/537,923, filed Mar. 29, 2000.
2) D. Sievenpiper, T. Y. Hsu, S. T. Wu, D. M. Pepper, “An Electronically Tunable Reflector”, U.S. Ser. No. 09/537,922, filed Mar. 29, 2000;
3) D. Sievenpiper, G. Tangonan, R. Loo, J. Schaffner, “A Tunable Impedance Surface”, U.S. Ser. No. 09/589,859, filed Jun. 8, 2000.
4) D. Sievenpiper, J. J. Lee, S. Livingston, “An End-Fire Antenna or Array on a Surface with Tunable Impedance”, U.S. Ser. No. 09/537,921, filed Mar. 29, 2000;
5) D. Sievenpiper, J. Schaffner, “A Textured Surface Having High Electromagnetic Impedance in Multiple Frequency Bands”, U.S. Ser. No. 09/713,119, filed Nov. 14, 2000.
6) D. Sievenpiper, H. P. Hsu, “A Polarization Converting Reflector”, U.S. Ser. No. 09/520,503, filed Mar. 8, 2000;
7) D. Sievenpiper, H. P. Hsu, G. Tangonan, “Planar Antenna with Switched Beam Diversity for Interference Reduction in Mobile Environment”, U.S. patent application Ser. No. 09/525,831 filed Mar. 15, 2000.
8) D. Sievenpiper, “A Vivaldi Cloverleaf Antenna”, U.S. Ser. No. 09/525,832, filed Mar. 15, 2000.
9) D. Sievenpiper, A. Schmitz, J. Schaffner, G. Tangonan, T. Y. Hsu, R. Y. Loo, R. S. Miles, “A Low-Cost HDMI-D Packaging Method for Integrating a Novel and Efficient Reconfigurable Antenna ces and High Impedance Surface”, U.S. Ser. No. 09906035 filed Jul. 13, 2001.
10) J. Schaffner, D. Sievenpiper, J. Lynch, R. Y. Loo, “A Reconfigurable Antenna for Multiple-Band, Beam Switching Operation”, U.S. Ser. No. 09/629,681, filed Aug. 1, 2000.
11) D. Sievenpiper, H. P. Hsu, J. Schaffner, G. Tangonan, “Low-profile, Multi-antenna Module, and a Method of Integration into Vehicle”, U.S. Ser. No. 09/905,757, filed on the same date as the present application.
As is briefly discussed above, with the advent of broadband wireless communication systems, there is a need for antennas that can meet stringent performance criteria. At the same time, vehicle styling and/or aerodynamic requirements prohibit the use of unsightly “antenna farms or forests” with multiple vertical antennas protruding from the surface of a vehicle. Hence, new antennas must not only have increased functionality to handle modern broadband wireless communication systems, but must also have a low-profile and should be conformable to the shape of the vehicle. In many situations, these two requirements are in direct conflict. For example, in modern communications systems, antennas should be able to handle low-angle radiation. For terrestrial systems, in which a mobile user is communicating with one or more base stations, the user must radiate energy at or near the horizon and typically in the microwave frequencies. For a handset such as a cellular phone, this is accomplished easily with a vertical whip antenna, which produces a nearly omnidirectional radiation pattern. For vehicle antennas, which are typically mounted on the top of the roof in order to obtain unobstructed coverage of all azimuthal angles, the presence of a large metal ground plane complicates the situation. In this case, a vertical monopole antenna is still sufficient for vertical polarization. However, as more functionality is added to the antenna, such as diversity combining, or beamforming, multiple monopole antennas then are needed, resulting in an unsightly and unaerodynamic “antenna farm or forest”. Furthermore, if horizontal polarization or circular polarization is required, the vertical monopole antenna is not a viable option.
Other antennas exist which have a low-profile and are capable of generating any desired polarization. The most common example of s
Hsu Hui-Pin
Schaffner James H.
Sievenpiper Daniel F.
Tangonan Gregory L.
HRL Laboratories, LLC.
Ladas & Parry
Nguyen Hoang
Wong Don
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