Not Applicable.
Not Applicable.
The present invention generally relates to helix radiating elements, and more specifically, to methods and devices for providing helix radiating elements for high power applications.
The power handling capability of a helix radiating element is known to be limited by heating effects in the first several turns of the wire. The limitation is usually in the dielectric that supports the wire. Currently, such limitation does not pose too much of a problem because the operating power levels are relatively low and common dielectrics are deemed to be sufficient for handling such power levels.
As applications become more and more capacity driven, there is a corresponding increase in demand for transmission of high power. Traditional dielectrics may no longer be able to perform within tolerable parameters. Consequently, the power handling capability of radiating elements needs to be improved to accommodate higher operating power levels.
Hence, it would be desirable to provide methods and devices that can be used to implement radiating elements to allow such elements to more effectively handle higher operating power levels.
The present invention improves the power handling capability of radiating elements. In one embodiment, a helix radiating element is disclosed. The helix radiating element includes a support, a base and a helix wire. The support is made up of a dielectric material including PEEK (Polyetheretherketone), a dielectric with high temperature capability. The base is coupled to the PEEK support and is made up of boron nitride. Boron nitride is a low-loss, high temperature ceramic that is thermally conductive. The helix wire is configured to be wrapped around the PEEK support and bonded to the base. The base is coupled to a ground plane. A boron nitride filled adhesive is used to bond the support to the base and bond the helix wire to the base. The boron nitride filled adhesive has thermal conduction capability. The boron nitride filled adhesive is also used to bond the base to the ground plane. Heat generated in the helix wire is transferred to the ground plane via the base.
Low RF (radio frequency) loss (dissipation) and thermally conductive boron nitride and boron nitride filled silicone adhesive dielectrics are tailor made to provide heat transfer from the helix wire to the ground plane. In order to minimize the mass yet provide adequate support structure for the wire, a composite bonded helix support structure of various dielectrics are used.
In one aspect, a method of assembling a helix radiating element is disclosed. The method includes wrapping a helix wire around a support, the support being made up of a dielectric material including PEEK, bonding one end of the helix wire to a base, the base being coupled to the support and made up of boron nitride, bonding a ground plane to the base, and using a boron nitride filled adhesive to bond the support to the base, bond the helix wire to the base and bond the base to the ground plane, wherein heat generated in the helix wire is transferred to the ground plane via the base.
The present invention may provide a number of advantages and/or benefits. For example, the present invention increases the power handling capability of a helix radiating element and improves the return loss match of the radiating element by use of dielectric matching.
Reference to the remaining portions of the specification, including the drawings and claims, will realize other features and advantages of the present invention. Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with respect to accompanying drawings, like reference numbers indicate identical or functionally similar elements.
Aspects, advantages and novel features of the present invention will become apparent from the following description of the invention presented in conjunction with the accompanying drawings:
The present invention in the form of one or more exemplary embodiments will now be described.
The helix wire 18 is wrapped around the support 16 and the base 20. In one embodiment, the helix wire 18 is made up of solid aluminum with a diameter of, for example, 0.080″. As noted above, the diameter of the helix wire 18 and its geometrical configuration (e.g., the helix diameter and pitch) around the support 16 are chosen such that the electromagnetic wave radiation and the power handling capability of the helix radiating element 10 are optimized. The helix wire 18 is secured into the grooves 22 along the edges of the panel section 26a–d to effect the desired geometrical configuration. Based on the disclosure and teachings provided herein, a person with ordinary skill in the art will appreciate how to select the appropriate diameter and geometrical configuration.
The helix wire 18 is made up of two (2) parts. One part is a cylindrical section with a uniform diameter of, for example, 0.080″. The second part is a lug 30. The lug 30 is also made of solid aluminum.
To further control heat dissipation, a number of bottom turns 36 (e.g., four (4) turns) of the helix wire 18 from the base 20 are painted with black thermal paint. The black thermal paint provides better thermal emissivity which helps dissipate heat further by radiation.
By using the helix element assembly 10, heat transfer or dissipation can be effectively managed in two ways, for example, via the properties of the boron nitride and the thermal paint on the helix wire 18. Due to the thermal conductivity properties of boron nitride, a heat transfer path is provided allowing heat from the helix wire 18 to dissipate via the ground plane 12. More specifically, heat generated in the helix wire 18 is transferred to the base 20 which, in turn, transfers the heat to the ground plane 12. Furthermore, use of boron nitride also permits transmission of high power through the helix wire 18 without burning up materials or multipacting at high power levels.
Boron nitride and the boron nitride filled adhesive experience low loss at RF frequency. Consequently, the use of boron nitride and boron nitride filled adhesive also minimizes RF dielectric losses.
The helix radiating element 10 has been successfully tested for high power handing in TVAC (thermal vacuum) chamber up to power level exceeding 240 watts at S-band. Since RF loss (i.e., dissipation) at lower frequencies is much less, even higher power levels can be achieved at lower frequencies.
Based on the disclosure and teachings provided herein, it should be understood that the present invention can be used in a variety of high power applications including, for example, RF communications circuitry for use in connection with satellites and other space-based applications. A person of ordinary skill in the art will appreciate other ways and/or methods to deploy the present invention in different types of applications.
The above description is illustrative but not restrictive. Many variations of the present invention will become apparent to those skilled in the art upon review of the disclosure. The scope of the present invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the pending claims along with their full scope or equivalents.
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