Patent Application
20070046556
This invention relates generally to radio frequency communications. More particularly, the invention relates to a system and apparatus for a wideband omni-directional antenna.
Wideband, low profile, omni-directional, small, efficient radiators are generally desired for many applications. These applications may range from military broadband single feed platforms, for example the Joint Tactical Radio System (“JTRS”) terminals, to multi-service wireless base stations. The JTRS systems are configured to be a multi-channel, multimode, and reprogrammable radio systems. Accordingly, the JTRS may likely require an antenna capable of receiving signals over a large bandwidth.
Possible solutions to requirements of the JTRS solution are spiral and Beverage antennas. Spiral and Beverage antennas typically offer a large bandwidth. However, there are drawbacks and disadvantages. For example, these antennas suffer from a lack of efficiency due to the resistive nature of the loading. Moreover, the efficiency of these types of antennas may drop even further as the size the antennas becomes smaller.
Log periodic based antennas and complementary antennas may also provide wideband efficient solution. However, their overall sizes (tens of wavelengths and multiple numbers of wavelengths, respectively) make these classes of antennas unwieldy. Moreover, complementary antennas may require complicated feed networks that can reduce their effective bandwidth.
Tapered slot antennas are another possible solution. Tapered slot antennas can perform over multiple octaves. However, like the previously mentioned antennas, tapered slot antennas can suffer from drawbacks and disadvantages. For instance, these antennas are typically electrically large and directional in nature.
Conventional bow tie antennas currently do not have sufficient bandwidth to support the services described earlier. Moreover, conventional bow tie antennas suffer from the requirement of having a complicated feed structure.
An illustrative embodiment generally relates to an antenna. The antenna includes at least two slot radiators, where each slot radiator has an input port and a profile that has been defined to optimize the return loss bandwidth of the antenna. The antenna also includes a transmission line and a circuit configured to connect the transmission line and the at least two slot radiators at the respective input ports. The circuit is also configured to match the impedance of the at least two slot radiators and the co-planar waveguide.
Another embodiment pertains generally to an antenna. The antenna includes at least two slot radiators, where each slot radiator having an input port. The antenna also includes a transmission line and a circuit configured to connect the transmission line and the at least two slot radiators at the respective input ports. The circuit is also configured to match the impedance of the at least two slot radiators and the transmission line. Moreover, the at least two slot radiators, the transmission line, and circuit are formed on a three-dimensional substrate.
Various features of the embodiments can be more fully appreciated as the same become better understood with reference to the following detailed description of the embodiments when considered in connection with the accompanying figures, in which:
For simplicity and illustrative purposes, the principles of the present invention are described by referring mainly to exemplary embodiments thereof. However, one of ordinary skill in the art would readily recognize that the same principles are equally applicable to, and can be implemented in, all types of radio frequency communication systems, and that any such variations do not depart from the true spirit and scope of the present invention. Moreover, in the following detailed description, references are made to the accompanying figures, which illustrate specific embodiments. Electrical, mechanical, logical and structural changes may be made to the embodiments without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense and the scope of the present invention is defined by the appended claims and their equivalents.
Embodiments relate generally to a system and apparatus for wideband omni-directional antenna that may be created from a series of slot radiators. The profile of the slot radiators are optimized to efficiently impedance match and efficiency match the antenna. More particularly, in various embodiments, a wideband omni-directional antenna may be fabricated from two slot radiators in a back-to-back configuration. Each slot radiator may be configured to receive power from a common point. The power may be distributed reactively to each slot radiator. In other embodiments, a resistive network may be use balanced with a reduction in efficiency. Each slot radiator may be further configured to optimize the return loss seen at its input terminal and to maximize the radiation efficiency.
As illustrated in
In this embodiment, each radiator 115 may be configured in a substantially half-bow tie configuration. Each radiator 115 may have a profile that is exponential (see exponential slot taper 125) to minimize the reflection power to the input port. In other embodiments, the profile may be linear, piece-wise linear, or other geometric configuration. The length and width of the taper may be a function of the lowest frequency required for operation and the amount of area available for the overall structure. In most embodiments, the dimensions of the taper should be at least 0.2 λ0 (where the wavelength λ0 corresponds to lowest frequency of operation of the antenna 100) to provide an efficient low return loss solution.
The profile of the slot closure 130 of each radiator 115 may have a substantially parabolic configuration. However, in other embodiments, the profile may be exponential, linear, piece-wise linear, or some other geometric configuration.
The antenna 100 may be implemented by creating the CPW feed 110 and the radiators 115 on a common substrate 105. The conductors may be etched on one side of the substrate 105 using standard printed circuit board fabrication processes. Common materials that can be used to develop the antenna (but is not limited to) include polyethylene, polyimide, FR4, silicon and Teflon.
As shown in
Returning to
As shown in
It should be noted that the proposed radiator is not limited to planar geometries. The radiator can also be formed on a variety of three-dimensional structures including cylinders, spheres and cones, as shown in
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5.
While the invention has been described with reference to the exemplary embodiments thereof, those skilled in the art will be able to make various modifications to the described embodiments without departing from the true spirit and scope. The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. In particular, although the method has been described by examples, the steps of the method may be performed in a different order than illustrated or simultaneously. Those skilled in the art will recognize that these and other variations are possible within the spirit and scope as defined in the following claims and their equivalents.
