INVISI-SHIELD™ Electrically Transparent Ice-Shield

Radial icing occurs when water droplets are large enough to fall from the atmosphere and freeze on objects near the ground. The frozen deposits form a clear ice shell on antenna and tower components. Radial ice conditions are typically very short in duration. The proceeding thaw releases segments of ice which fall or sail causing significant damage to antenna elements.

The antenna elements are particularly susceptible to falling ice. Radial ice has a unit weight of 56 pound per cubic foot and can cause significant damage to unprotected tower appurtenances. Steel ice shields can offer some degree of protection. But due to pattern distortion inherent to their construction the steel shields are placed at distances which diminish their ability to adequately protect the antenna. Some applications of a steel ice shield are prohibited due to the detracting effects it could have on neighboring antennas.

The ERI INVISI-SHIELD™ is an electrically transparent ice shield. Utilizing custom fabricated materials and careful placement of connection components has resulted in a structure which has no perceptible effect on the antenna’s pattern. The INVISI-SHIELD™ can be mounted directly over an antenna element. This close proximity allows the INVISI-SHIELD™ to be significantly smaller while increasing protection when compared to a steel shield. The smaller size also results in less load to the tower. The electrical transparency of the INVISI-SHIELD™will permit installation between antenna bays in extreme icing conditions. The top edge of the INVISI-SHIELD™ is permeated with a silicone grit. This material helps trap potential freezing rain on the shield reducing the potential of radial ice accumulation and detuning of the antenna element.

Specifications

  • Load Rating:
    300 PSF uniform distribution 7,200 lbs. total capacity, High Impact Resistance
  • Size:
    6 ft x 4 ft | 1.83 m x 1.22 m
  • Weight:
    120 lbm | 54.43 kg
  • Wind Load:
    320 pounds (50/33psf ) (EIA RS-222-C)
  • Ac:
    6.5 square feet projected area of discrete appurtenance
  • Ca:
    2, discrete appurtenance force coefficient
  • CaAc:
    13 square feet (ANSI/EIA-222-D)

Features and Benefits

  • Protection from falling ice
  • No perceptible pattern distortion
  • Can be mounted directly over each element
  • Reduces potential accumulation of radial ice
  • Convenient work platform

Related Publications

Structural Components and Accessories

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