Abstract:
Embodiments of the present invention include antennas for transmitting and receiving electromagnetic signals. The antennas are configured to transmit a first electromagnetic signal at full power via a first set of radiating elements and to transmit the first electromagnetic signal at an attenuated power via a second set of radiating elements to decrease side lobes associated with the transmission of the first electromagnetic signal. The antennas are configured to receive a second electromagnetic signal having an associated first power level via the second set of radiating elements and to form an aggregated electromagnetic signal having a second power level that is a multiple of the first power level. The antennas are configured to attenuate the aggregated signal to form an attenuated electromagnetic signal having a third power level to facilitate uniform reception of the second electromagnetic signal and tapered transmission.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to U.S. Provisional Patent Application Ser. No. 60/967,042 filed Aug. 31, 2007, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to antennas, and more particularly to polypod antennas. 
         [0004]    2. Brief Discussion of Related Art 
         [0005]    An array antenna can include a number of transmitting/receiving elements. Tapering is preferably achieved by applying specific attenuation to sets of radiating elements. The attenuation applied to sets of radiating elements can have the effect of decreasing the sidelobes of the overall antenna. Typically, however, when the antenna is receiving a signal, the effect of tapering is still apparent and so the reception is non-uniform. This non-uniform reception is often detrimental to the receiving system and can cause a decrease in isolation on a beamformer network connected to the input of a phased array antenna. Therefore, it is beneficial and/or advantageous to taper transmission without tapering reception. 
       SUMMARY OF THE PRESENT INVENTION 
       [0006]    In some aspects, a device for transmitting and receiving electromagnetic signals including an antenna. The antenna is configured to transmit a first electromagnetic signal at full power via a first set of radiating elements and to transmit the first electromagnetic signal at an attenuated power via a second set of radiating elements to decrease side lobes associated with the transmission of the first electromagnetic signal. The antenna is configured to receive a second electromagnetic signal having an associated first power level via the second set of radiating elements and to form an aggregated electromagnetic signal having a second power level that is a multiple of the first power level. The antenna is configured to attenuate the aggregated signal to form an attenuated electromagnetic signal having a third power level to facilitate uniform reception of the second electromagnetic signal and tapered transmission. 
         [0007]    In other aspects, a method for receiving and transmitting an electromagnetic signal is disclosed. The method includes radiating a first electromagnetic signal at full power via a first set of radiating elements, radiating the first electromagnetic signal at an attenuated power via a second set of radiating elements to decrease side lobes associated with the transmission of the first electromagnetic signal, and receiving a second electromagnetic signal having an associated first power level via the second set of radiating elements. The method also includes forming an aggregated electromagnetic signal having a second power level that is a multiple of the first power level and attenuating the aggregated signal to form an attenuated electromagnetic signal having a third power level to facilitate uniform reception of the second electromagnetic signal and tapered transmission. 
         [0008]    In yet other aspects, an antenna configured for tapered transmission and untapered reception is disclosed. The antenna includes radiating elements, a power manipulation unit, and an attenuator. The radiating elements configured to receive an electromagnetic signal propagating through a medium and to convert the electromagnetic signal into guided electromagnetic signals. The power manipulation unit is operatively coupled to a set of the radiating elements The power manipulation unit is configured to aggregate the guided electromagnetic signals received by the set of the radiating elements to form an aggregated signal. The attenuator is operatively coupled to the power manipulation unit to receive the aggregated signal. The attenuator is configured to attenuate the aggregated signal to facilitate uniform reception. 
         [0009]    Aspects of the present invention will become apparent upon consideration of the disclosed preferred embodiments, particularly when taken in conjunction with the accompanying drawings, wherein like reference numerals in the various figures are utilized to designate like components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  depicts a block diagram of a polypod antenna in accordance with a preferred embodiment of the present invention; and 
           [0011]      FIG. 2  depicts an arrangement of radiating elements of a polypod antenna in accordance with a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    Preferred embodiments of the present invention are directed to polypod antennas that utilize a technique for achieving tapered transmission on an antenna array, but maintaining uniformity when receiving. The polypod antennas achieve tapered transmission and non-tapered reception by preferably employing a combination of attenuators and power manipulation units. The attenuators are preferably placed on or before the feeding network of the antenna in order to attenuate a desired set of radiating elements. To eliminate or counteract the attenuation when receiving with the polypod antenna, the number of elements for the attenuated set of radiating elements is preferably increased. 
         [0013]      FIG. 1  depicts an exemplary block diagram of a preferred embodiment of the polypod antenna  100 . The polypod antenna  100  preferably includes a transceiver  110 , radiating elements  120   a - f , attenuators  130 ′ and  130 ″ (collectively referred to herein as “attenuators  130 ”), and power manipulation units  140 ′ and  140 ″ (collectively referred to herein as “power manipulation units  140 ”). The power manipulation units  140  can include power dividers, which distribute or divide power of one or more signals between multiple radiating elements, and/or a power aggregator, which aggregates or multiples power of one or more signal to form a signal with amplified, intensified, or multiplied power. 
         [0014]    The transceiver  110  is preferably adapted to transmit and/or receive electromagnetic signals via the radiating elements  120   a - f . The transceiver  110  can have a number of connecting feed lines. In this example, the transceiver  110  has four connecting feed lines  112 - 118 . The two middle radiating elements  120   c - d  are preferably connected to the transceiver  110  via connecting feed lines  114  and  116 , respectively, without any attenuation. The sets of side radiating elements  120   a - b  and  120   e - f  are preferably connected to the transceiver  110  through attenuators  130  and power manipulation units  140  via connecting feed lines  112  and  118 , respectively. 
         [0015]    The radiating elements  120   a - f  can preferably receive free space electromagnetic signals propagating through the air and/or can transmit guided electromagnetic signals by radiating the guided electromagnetic signals received from the transceiver  110 . 
         [0016]    Attenuators  130 ′ and  130 ″ attenuate the sets of radiating elements  120   a - b  and  120   e - f , respectively, to provide tapered guided electromagnetic signals passing to the sets of radiating elements  120   a - b  and  120   e - f . In this manner, the set of radiating elements  120   a - b  and the set of radiating elements  120   e - f  radiate an attenuated version of the guided electromagnetic signal, while the radiating elements  120   c - d  radiate the guided electromagnetic signal at full power. For example, the attenuators  130  preferably reduce the power of a signal that passes through the attenuator by one half (e.g., 3 dB) or by other amounts. The attenuation applied to sets of radiating elements  120   a - b  and  120   e - f  can preferably have the effect of decreasing the sidelobes of the overall antenna  100  during transmission, which is referred to herein as “tapered transmission”. 
         [0017]    The power manipulation units  140  distribute signal power between the radiating elements connected to the power manipulation units  140 . For example, the radiating elements  120   a - b  are preferably connected to the power manipulation unit  140 ′. Signal power is distributed between radiating elements  120   a - b  via the power manipulation unit  140 ′. Likewise, the radiating elements  120   e - f  are preferably connected to the power manipulation unit  140 ″. Signal power is distributed between the radiating elements  120   e - f  via the power manipulation unit  140 ″. 
         [0018]    During transmission, a guided electromagnetic signal to be transmitted is sent from the transceiver  110  to the radiating elements  120   a - f  via the connecting feed line  112 - 118 . The connecting feed line  114  guides the electromagnetic signal to the radiating element  120   c . The connecting feed line  116  guides the electromagnetic signal to the radiating element  120   d . The connecting feed line  112  guides the electromagnetic signal through the attenuator  130 ′, where the electromagnetic signal is attenuated. Subsequently, the attenuated signal enters the power manipulation unit  140 ′ where the attenuated signal is distributed between the radiating elements  120   a - b . Likewise, the connecting feed line  118  guides the electromagnetic signal through the attenuator  130 ″ and the power manipulation unit  140 ″ to the radiating elements  120   e - f . The power manipulation unit  140 ″ distributes the signal power between the radiating elements  120   e - f . The radiating elements  120   c - d  radiate the signal at its full power and the sets of radiating elements  120   a - b  and  120   e - f  radiate the attenuated signal. 
         [0019]    For example, during transmission, the transceiver  110  may pass a 1 [units] signal through each of the connecting feed lines  112 - 118 . Each of the connecting feed lines  114  and  116  can guide the 1 [units] signal to the radiating elements  120   c  and  120   d , respectively. Each of the radiating elements  120   c - d  can then radiate the 1 [units] signal. Each of the connecting feed lines  112  and  118 , however, guide the 1 [units] signal through the attenuators  130  to reduce the 1 [units] signal to a ½ [units] signal. The ½ [units] signal is passed through the power manipulation units  140 , which distributes the ½ [units] signal on the connecting feed line  112  between the radiating elements  120   a - b  and distributes the ½ [units] signal on the connecting feed lines  118  between the radiating elements  120   e - f . In one embodiment, the power manipulation units  140  distribute the ½ [units] signal equally such that each of the radiating elements  120   a - b  and  120   e -fradiate a ¼ [units] signal. 
         [0020]    During reception, each of the radiating elements  120   a - f  receives a free space electromagnetic signal propagating through a medium, such as air. The free space electromagnetic signal received by the radiating elements  120   c - d  is preferably guided by connecting feed line  114  and  116 , respectively, to the transceiver  110 . The free space electromagnetic signal received by the radiating elements  120   a - b  is converted into a guided electromagnetic signal that is guided through the power manipulation unit  140 ′, where the electromagnetic signals from each of the radiating element  120   a - b  are combined. The combination preferably creates an intensified or aggregated signal that is based on the number of radiating elements  120   a - b  that are used. The intensified signal passes through the attenuator  130 ′, where the intensified signal is attenuated. The result of the attenuation is that the power of the intensified signal is reduced. The signal received by the radiating elements  120   e - f  can undergo the same process as the signal received by radiating elements  120   a - b . The number of radiating elements  120  for the sets of radiating elements  120   a - b  and  120   e - f  is preferably specified to compensate for the attenuation during reception of a signal by the sets of radiating elements  120   a - b  and  120   e - f.    
         [0021]    For example, during reception, the attenuators  130  may reduce the power of a signal on the connecting feed lines  112  and  118  by one half (½). In this example, each connecting feed line  112  and  118  that includes attenuators  130  has two radiating elements  120   a - b  and  120   e - f  to compensate for the attenuation of the attenuators  130 . The antenna  100  may receive a 1 [units] signal with each of the radiating elements  120   a - b . The 1 [units] signal from each radiating elements  120   a - b  passes through the power manipulation unit  140 ′ which combines the 1 [units] signal from each of the radiating elements  120   a - b  to form a 2 [units] signal. Subsequently, the 2 [units] signal passes through the attenuator  130 ′, which reduces the 2 [units] signal by one half (½) to form a 1 [units] signal. The 1 [units] signal is guided by the connecting feed line  112  to the transceiver  110  for processing. Therefore, the transceiver  110  receives a signal that accurately represents the signal received by the antenna  100 . 
         [0022]    Therefore, the polypod antenna  100  transmits a tapered signal via the sets of radiating elements  120   a - b  and  120   e - f  as a result of the attenuation performed by the attenuators  130 . During reception, however, because there are sets of multiple radiating elements  120   a - b  and  120   e - f  for each attenuated connecting feed line  112  and  118 , where each set can aggregate the signals, the attenuation compensated. 
         [0023]      FIG. 2  depicts an arrangement of radiating elements  120  in accordance with a preferred embodiment of the present invention. The sets of radiating elements  120   a - b  and  120   e - f  are constructed by placing the radiating elements  120   a - b  in close proximity to each other and by placing the radiating elements  120   e - f  in close proximity to each other. However, an appropriate distance is preferably maintained between the radiating elements  120   a - b , as well as between the radiating elements  120   e - f  so that there is no gain reduction due to effective area overlap. 
         [0024]    The sets of radiating elements  120   a - b  and  120   e - f  can be arranged along an x-axis  210  or a y-axis  220 . In a preferred embodiment, the set of radiating elements  120   a - b  are aligned along the y-axis  220  as is the set of radiating elements  120   e - f . This arrangement allows the horizontal beamwidth of each set  120   a - b  and  120   e - f  to have the same horizontal beamwidth as the single elements  120   c - d  of the array. 
         [0025]    While the preferred embodiment depicts sets of two (2) radiating elements  120   a - b  and  120   e - f  for each attenuated connecting feed line  112  and  118 , respectively, one skilled in the art will appreciate that any number of radiating elements can be used for each attenuated connecting feed line. In addition, the number of radiating elements for each set can be based on the amount of attenuation used. 
         [0026]    Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention.