Fall protection apparatus and method

An attachment apparatus for use with a generally vertical radio frequency antenna, the antenna having a housing defining an inside and an outside of the antenna, wherein the housing has an upper portion and a lower portion. The apparatus includes first and second anchor housings connected to the antenna along with a revolving cable having two sections. The attachment apparatus also includes at least one latching mechanism.

FIELD OF THE INVENTION

The present invention relates generally to a fall protection apparatus and method. More particularly, the present invention relates to an apparatus and method for supporting persons on a structure when climbing, for example, a tower, mast, antenna or other elevated structure for maintenance or any other purpose.

BACKGROUND OF THE INVENTION

Due to the enactment of various safety laws, persons working at elevated positions, for example, broadcast radio-frequency (RF) antennas or towers, are required to be protected against falls. The antennas commonly extend approximately 20-200 feet high and are typically mounted at the top of a tower, building or similar structure that can extend an additional 100-1500 feet high. Commonly, radiation emanates 360° from around the antenna's aperture and can radiate RF waves at powers ranging from approximately 10 kW to approximately 500 kW depending on the area to be covered.

Antenna installations like the one described above oftentimes employ fall prevention systems and/or attachment anchoring mechanisms that are connected to, or part of, the antenna. Typically, these fall prevention systems or attachment mechanisms typically utilize ropes or cables, referred to as rope grabs, to which a worker may anchor him or herself when installing, servicing, maintaining or sealing the antenna and or obstruction lights mounted on the antenna.

The rope or cables currently used in rope grabs are typically constructed from metal materials such as stainless steel, galvanized steel, aluminum and the like. Alternatively, other types of ropes currently used in fall prevention systems are constructed from synthetic materials such as nylon, polypropylene, Keviar® and the like.

The above-described ropes currently used in fall prevention systems have drawbacks however. For example, the synthetic ropes can be susceptible to the environment in which the antenna is located compromising the ropes' lifespan. Also, the synthetic materials from which the ropes are manufactured oftentimes do not resist ultraviolet (UV) rays or the RF radiation to which they are exposed, causing the ropes to break down or deteriorate over time. In addition, these synthetic ropes are also susceptible to the infiltration of water from the environment which also can lead to deterioration. Consequently, frequent maintenance and/or replacement of the ropes is sometimes required. Moreover, these ropes can be very expensive to manufacture or purchase. Thus, fall prevention systems currently employed in the art using synthetic materials may require frequent, costly maintenance. Additionally, with the absorption of water the material's dielectric constant is increased.

The ropes, or cables constructed from metal materials typically do not suffer from the above-described drawbacks associated with the use of synthetic ropes, however the metallic construction does have drawbacks. As previously described, an RF antenna typically emits a 360° radiation pattern. Metallic ropes will reflect the RF waves back to the antenna, causing a distortion of the radiation pattern. A metallic cable that is ungrounded can develop an electrical potential different from that of the antenna structure. This electrical potential can cause an are between the antenna structure and the cable. This will cause interference in the RF signal as well as destroy the cable.

Accordingly, there is a need in the art to provide a fall protection apparatus and method that is resistant to the environment in which it is deployed, reducing the amount of maintenance required for operation. Moreover, there is an additional need for a low maintenance fall protection system that is affordable. Further, there is a need for such an apparatus and method that minimizes distortion of the antenna's radiation pattern.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an attachment apparatus is provided for use with a generally vertical radio frequency antenna having a support frame defining an inside and an outside of the antenna. The support frame includes an upper portion and a lower portion. The attachment apparatus includes a first anchor housing connected to the upper portion of the support frame and a second anchor housing connected to the lower portion of the antenna housing. The apparatus also has a revolving cable which includes a first section constructed from a first material and a second section constructed from a second material. A portion of the cable is disposed within the support frame of the antenna and a portion of the cable is disposed outside of the support frame. The attachment apparatus also includes a latching mechanism that activates to prevent said cable from rotation.

In accordance with another embodiment of the present invention, a radio frequency antenna is provided having a means for supporting the antenna and defining an inside and an outside of the antenna. The support means has an upper portion and a lower portion. The attachment apparatus includes a first anchoring means connected to the upper portion of the support means and a second anchoring means connected to the lower portion of the support means. The apparatus also has a revolving cable having a first section constructed from a first material and a second section constructed from a second material. The cable is oriented so that at least a portion of the cable is disposed within the supporting means of the antenna and at least a portion of said cable is disposed outside of the supporting means. The apparatus also has a means for latching the cable and a latching means that prevents said cable means from rotating.

In accordance with yet another embodiment of the present invention, a method for attaching to a vertical radio frequency wave emitting structure having an antenna, wherein the antenna has a support frame defining an inside and an outside of the antenna and an upper portion and a lower portion, and including a revolving cable that extends between the upper portion and the lower portion, wherein the cable comprises two sections made from two materials, is provided comprising the steps of: rotating the cable to a first operational position, locking the cable in the first position to prevent the cable from further rotation, and attaching an attachment mechanism to the revolving cable.

In accordance with still another embodiment of the present invention, a radio frequency antenna is provided. The radio frequency antenna includes a support frame that supports the antenna and defines an inside and an outside of the antenna. The support frame includes an upper portion and a lower portion along with a first anchor connected to the upper portion and lower anchor connected to the lower portion. The radio frequency antenna also includes a revolving cable having a first section constructed from a first material and a second section constructed from a second material. At least a portion of the cable is disposed within the support frame of the antenna while at least a portion is dispose outside the support frame of the antenna. The radio frequency antenna additionally includes at least one latching mechanism that prevents the cable from rotating.

In accordance with yet another embodiment of the present invention, an attachment apparatus is provided for use with a generally vertical radio frequency antenna having a support frame defining an inside and an outside of the antenna. The support frame includes an upper portion and a lower portion. The attachment apparatus includes a first anchor housing connected to the upper portion of the support frame and a second anchor housing connected to the lower portion of the antenna housing. The apparatus also has a revolving cable which includes a first section constructed from a first material and a second section constructed from a second material. A portion of the cable is shielded from RF energy during antenna operation and a portion of the cable is exposed to RF energy during antenna operation. The attachment apparatus also includes a latching mechanism that activates to prevent said cable from rotation.

In accordance with another embodiment of the present invention, a radio frequency antenna is provided. The radio frequency antenna includes a support frame that supports the antenna and defines an inside and an outside of the antenna. The support frame includes an upper portion and a lower portion along with a first anchor connected to the upper portion and lower anchor connected to the lower portion. The radio frequency antenna also includes a revolving cable having a first section constructed from a first material and a second section constructed from a second material. At least a portion of the cable is shielded from RF energy during antenna operation while at least a portion is exposed to RF energy during antenna operation. The radio frequency antenna additionally includes at least one latching mechanism that prevents the cable from rotating.

DETAILED DESCRIPTION

Various preferred embodiments of the present invention provide for a safety apparatus and method for securing a person to an elevated structure or work area. In some arrangements, the apparatus and method are utilized as a fall prevention system for attaching persons to a structure or anchor when climbing a vertical top mounted antenna to perform maintenance or other tasks. It should be understood, however, that the present invention is not limited in its application top mounted antennas or the broadcast industry, but, for example, can be used with other processes and industries that require a system for preventing persons from falling when climbing for example, a pylon, tower, vertical structure or the like. Embodiments of the present invention may also be suitable to hoist or support other objects besides or in addition to persons, such as, for example, equipment or other objects. The invention will now be further described with reference to the drawing figures, in which like reference numerals refer to like parts throughout.

Referring now to the figures,FIGS. 1-3and5illustrate a fall prevention system, generally designated10, in accordance with an embodiment of the present invention. WhereasFIG. 1depicts the apparatus10in the non-operational position,FIG. 2depicts the apparatus10in the operational position.

As illustrated in theFIGS. 1-3and5, the system10is installed or attached to a generally vertical top mount antenna12, for example, of a high power RF broadcasting antenna. The antenna12generally includes a top14, a base16, a support frame18, a shroud made from low dielectric constant material20and a plurality of radiators22. The antenna12also includes an inner conduit24positioned within the support frame18that extends at least partially but preferably the entire distance between the base16and the top14of the antenna12.

FIG. 5is a cross section view of the fall prevention system10in combination with an antenna12, showing as an example a central conduit24. The present invention embodies alternative designs which may include antennas with more or less radiators18and/or antennas which have multiple inner conduits24. In addition, the inner conduit(s)24need not be central, but may be oriented at varying positions within the antenna12itself. For example, conduits24may be located in some or all radial fins25of the support frame16.

The fall prevention apparatus10generally includes a safety rope or cable26mounted generally vertical along the top mount antenna12. As illustrated inFIGS. 1-4, the rope or cable26is preferably a single, continuous revolving or rotatable loop having two sections. The safety rope or cable26extends generally parallel to the outside of the antenna12. It then extends from the base16to the top14through the conduit24through the support frame18of the antenna12.

The first cable section, generally designated28, is preferably constructed from a metallic or metal alloy material such as stainless steel and is used for securing a person to the antenna12when the apparatus10is in the operational position. The second cable section, generally designated30, is a “messenger” rope or section, preferably manufactured from synthetic materials of low dielectric constant such as Kevlar® or polypropylene. The messenger section30is utilized to translate or promote the rope or cable26from the non-operational position as depicted inFIG. 1, to the operational position as depicted in FIG.2.

As depicted inFIGS. 1-3, in one embodiment of the present invention, the safety rope or cable assembly26is anchored to the top14of the antenna12via an anchor housing32and to the base16via another anchor housing34. The anchor housings32,34are preferably curved or shaped conduits having inner channel surfaces that allow the cable assembly26to slide over the channels to be rotated from the non-operational position to the operational position and vice versa. In the embodiments depicted, the anchor conduits32,34are proximate to the inner conduit24that extends between the top14and the base16, to provide a single, continuous path within which the rope or cable assembly26may travel. The anchor conduits32,34, however may be positioned anywhere in the antenna support frame18so long as the anchor conduits32,34are grounded to the antenna12.

The anchor housings32and/or34include a latching mechanism or brake such as is known in the art, for example a cam arrestor, that functions to stop rapid cable assembly26movement and/or to lock the cable assembly26in position when the apparatus10is in operation. The anchor housings32,34additionally include tension equalization systems known in the art which assist to reduce cable weight differentiation which can occur when the apparatus10is in operation. Anchor housing may also include lock out/tag out device to prevent accidentally applying power to the antenna12while apparatus10

FIG. 5illustrates a detailed cross-sectional view taken along line A—A in FIG.1. The cross-sectional view is an exemplary depiction of an antenna12that may be used in combination with the fall prevention apparatus10of the present invention. As depicted, the antenna12is an RF antenna having four radiators22, a support frame18and a radio-transparent skin20(known within the industry as a radome.

The radio-transparent skin20can be any protective layering known in the art whose properties exhibit a low dielectric constant, thus allowing for RF transmission while functioning as a barrier between the inner components of the antenna12and the environment in which the antenna is deployed. Preferably, the aforementioned barrier or skin is constructed from a polycarbonate and/or fiberglass material. The antenna12additionally includes an inner housing24. As one skilled in the art would appreciate, an RF antenna like the one depicted inFIG. 5most likely would employ significantly more radiators22than the four shown. However, some RF antenna designs may employ less. Moreover, though a single, centralized inner conduit24through which the cable assembly26travels is depicted, alternative embodiments may be employed. For example, the inner conduit24need not be centralized and can be positioned along the circumference or outer boundaries of the support frame18such as being in one or more of the radial fins25. The conduit24may also be attached and grounded to the support structure18of the antenna12. Furthermore, the cable assembly26may be positioned at a location between the radio-transparent skin20and the frame assembly18, for example in the space adjacent or next to the radiators22, or the cable26need not travel through the inside of the support frame18at all.

Referring now toFIG. 1, the fall prevention apparatus10is depicted in the non-operational position. By non-operational position, it is understood that the antenna12is functioning and the radiators are emitting RF energy. In this position, the cable assembly26is rotated and locked in a first position as indicated in FIG.1. In the aforementioned first position, the first section30(or metallic section) of the cable assembly26is disposed within the inner housing conduit24, shielded from the RF energy being emitted by the radiators22. Moreover, the second section28of the cable assembly26is located on the outside of the antenna12. In the non-operational position, the anchor housings32,34preferably assist to shield the first section28also.

Accordingly, in the aforementioned non-operational position, the first section30is shielded from the RF energy, reducing the likelihood of RF signal interference and reducing the likelihood that the cable will be destroyed by arcing.

As shown inFIG. 2, the fall prevention apparatus10is in operational position. By operational position it is understood that the radiators18of the antenna12are not actively emitting RF energy and the cable assembly26is rotated and locked in a second position. In the aforementioned second position, the first section28(or metallic section) extends along the outside of antenna12. In this position, the cable is securely locked in a stationary position via the latching mechanism and the tension equalization system. In the operational position, the cable assembly26provides an anchor and/or attachment point to a person wearing a harness or any other suitable climbing system may attach a device typically known of as a rope grab.

Referring now toFIG. 4, an alternative embodiment of the present invention is illustrated. Instead of the fixed, channel type anchor housings32,34utilized in the embodiments depicted inFIGS. 1-3, the embodiment depicted inFIG. 4employs anchor housings38,40that function via a wheeled pulley system. As illustrated inFIG. 4, each of the anchor housings38,40employs a pulley wheel42,44that allows the cable to be rotated from the non-operational position to the operational position and vice versa. Like the embodiment depicted inFIGS. 1-3, these housings38,40include latching mechanisms or brakes known in the art such as cam arrestors, that function stop rapid cable assembly26movement and/or to lock the cable assembly26in position when the apparatus10is in operation. And like the previous described embodiment, the anchor housings38,40additionally include tension, equalization systems known in the art which assist to reduce cable weight differentiation which can occur when the apparatus10is in operation.