Communications: radio wave antennas – Antennas – High frequency type loops
Reexamination Certificate
2002-06-01
2004-08-10
Vannucci, James (Department: 2821)
Communications: radio wave antennas
Antennas
High frequency type loops
C343S741000, C343S866000
Reexamination Certificate
active
06774859
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to electromagnetic energy radiation and reception, and especially relates to electromagnetic energy radiation and reception effected using impulse radio energy. Still more particularly the present invention provides an antenna that exhibits a generally continuous signal response between a first frequency and a second frequency and further exhibits a deviation from the signal response substantially at a selected frequency between the first frequency and the second frequency.
2. Related Art
Recent advances in communications technology have enabled an emerging, revolutionary ultra wideband technology (UWB) called impulse radio communications systems (hereinafter called impulse radio).
Impulse radio was first fully described in a series of patents, including U.S. Pat. No. 4,641,317 (issued Feb. 3, 1987), U.S. Pat. No. 4,813,057 (issued Mar. 14, 1989), U.S. Pat. No. 4,979,186 (issued Dec. 18, 1990) and U.S. Pat. No. 5,363,108 (issued Nov. 8, 1994) to Larry W. Fullerton. A second generation of impulse radio patents includes U.S. Pat. No. 5,677,927 (issued Oct. 14, 1997) to Fullerton et al; and U.S. Pat. No. 5,687,169 (issued Nov. 11, 1997) and U.S. Pat. No. 5,832,035 (issued Nov. 3, 1998) to Fullerton. These patent documents are incorporated herein by reference.
Uses of impulse radio systems are described in U.S. patent application Ser. No. 09/332,502, entitled, “System and Method for Intrusion Detection Using a Time Domain Radar Array,” and U.S. patent application Ser. No. 09/332,503, entitled, “Wide Area Time Domain Radar Array,” both filed Jun. 14, 1999, both of which are assigned to the assignee of the present invention, and both of which are incorporated herein by reference.
Basic impulse radio transmitters emit short pulses approaching a Gaussian monocycle with tightly controlled pulse-to-pulse intervals. Impulse radio systems typically use pulse position modulation, which is a form of time modulation where the value of each instantaneous sample of a modulating signal is caused to modulate the position of a pulse in time.
For impulse radio communications, the pulse-to-pulse interval is varied on a pulse-by-pulse basis by two components: an information component and a pseudo-random code component. Unlike direct sequence spread spectrum systems, the pseudo-random code for impulse radio communications is not necessary for energy spreading because the monocycle pulses themselves have an inherently wide bandwidth. Instead, the pseudo-random code of an impulse radio system is used for channelization, energy smoothing in the frequency domain and for interference suppression.
Generally speaking, an impulse radio receiver is a direct conversion receiver with a cross correlator front end. The front end coherently converts an electromagnetic pulse train of monocycle pulses to a baseband signal in a single stage. The data rate of the impulse radio transmission is typically a fraction of the periodic timing signal used as a time base. Because each data bit modulates the time position of many pulses of the periodic timing signal, this yields a modulated, coded timing signal that comprises a train of identically shaped pulses for each single data bit. The impulse radio receiver integrates multiple pulses to recover the transmitted information.
Antennas having ultra-wide band (UWB) properties are desired for a variety of applications, including impulse radio applications for communications, positioning, and other uses. Historically the principal use of UWB antennas has been in multi-band communication systems. Such multi-band communication systems require an ultra-wide band antenna that can handle narrow band signals at a variety of frequencies.
The recently emerging impulse radio communications technology often referred to as impulse radio has placed different, more stringent requirements on antenna performance. Impulse radio communication uses UWB signals, so an antenna for use in an impulse radio system must transmit or receive (or, transmit and receive) over all frequencies across an ultra-wide band at the same time. Thus, ultra-wide band impulse radio requires that an antenna performs well over ultra-wide bandwidths, and is also non-dispersive of those signals.
One solution applied to meeting the increasing commercial demand for multi-band systems has been to combine a variety of different narrow band operational modes in one antenna device. For example, a mobile phone may be provided with an antenna apparatus that can operate with cellular phone frequencies around 850 MHz, as well as operate with PCS (personal communication service) frequencies around 1900 MHz. For economic and cosmetic reasons (such as compact size), it is desirable that a multi-band device be provided with a single antenna that can function at potentially widely separated narrow bands of interest.
Widespread deployment of ultra wideband or “UWB” systems that use wide expanses of bandwidth in their operation, leaves the systems and apparatuses using such UWB antennas vulnerable to whatever narrowband sources of interference might co-exist in a given environment.
A variety of techniques have been used to create multi-band antennas in the past. One technique uses a tuned antenna that relies on a variable reactance, such as a variable capacitor or variable inductance, to create a resonance for making the antenna effective over a particular narrow band of interest. Even with the advent of more sophisticated micro-electro-mechanical systems (MEMS), such tuned antennas require a potentially complicated, expensive, and bulky tuning system that may not be commercially optimal.
Another technique has involved creating a single antenna that is responsive to multiple narrow bands of interest. Such an antenna is commonly constructed as a composite structure of narrow band resonant antenna sections that can operate in their respective corresponding narrow bands of interest.
An exemplary such prior art composite multi-band antenna may, for example, include an assembly of a variety of narrowband structures, such as a low band structure having a spectral response that is resonant around a first center frequency f
A
, a mid-band structure having a spectral response that is resonant around a second center frequency f
C
, and a high-band structure having a spectral response that is resonant around a third center frequency f
E
. The respective center frequencies f
A
, f
C
, f
E
are established according to the relationship:
f
A
<f
C
<f
E
Such a composite multi-band antenna has a spectral response that is resonant at a low frequency f
A
, at a mid frequency f
C
, and at a high frequency f
E
. Such a composite multi-band antenna is preferably designed to be nonresponsive at a first boundary frequency f
B
between f
A
and f
C
and to be nonresponsive at a second boundary frequency f
D
between f
C
and f
E
. Use of terms like “low,” “mid,” and “high,” are for illustrative purposes only and should not be construed as referring to any particular range of frequencies. Similarly, although the hypothetical composite multi-band antenna is described as being responsive to three narrow bands, this does not preclude the present discussion from pertaining to dual band antennas, nor to antennas responsive to four or more bands.
The approach described above relating to constructing a composite antenna structure for establishing operational responsiveness in a plurality of narrow bands delineated by nonresponsive boundary frequencies within a wide band of frequencies is fraught with difficulties and disadvantages. Although the respective narrowband resonant structures may individually be quite responsive to their particular narrowband resonant frequencies of interest, when the various narrow band structures are combined together to form a composite multi-band antenna the performance of the respective narrowband resonant structures will inevitably degrade. Mutual coupling may be introduced between or among respective narrowband resonant structures that c
Schantz Hans G.
Wolenec Glenn P.
Law Office of Donald D. Mondul
Time Domain Corporation
Vannucci James
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