ROTOTILLER ® X Series Circularly Polarized FM Antenna

Characteristics

  • Product Line
    ROTOTILLER®
  • Frequency Range
    88 - 108 MHz
  • Multiplexed Versions Available
    Yes
  • Broadband Applications
    No
  • Polarization
    Circular
  • Azimuth Pattern Circularity
    ± 2 dB in free space
  • Axial Ratio
    Less than 3 dB in free space
  • VSWR at Input
    1.07:1 or less (with field matching)
  • 1.25:1 or less (with top pole or LAMBDA™ Mount)
  • 1.50:1 or less (top mounted without field matching)
  • Maximum Power Rating
    120 kW

ERI antennas are unchallenged in quality and dependability. ERI is the only manufacturer to use large diameter outer conductors and a completely enclosed, pressurized, internal series feed system. The result is a simple and reliable method of coupling power to the elements. Unlike competing designs, ERI series fed antennas do not require a troublesome secondary current loop for element excitation with all the resulting disadvantages. All ERI antennas include brackets for mounting on leg, pole, or face mounting (up to 42-inch uniform cross section tower); brackets for other mounting configurations are optionally available.

ERI’s original and distinctive design combines the exceptional engineering features of an internally fed, fully pressurized system with superior fabrication characterized by totally welded feed connections, rugged brass material and TIG welding. The ROTOTILLER® X Series FM antenna’s unique design consists of two series fed, bent dipole elements which form a space phased, circularly polarized radiator. The antenna’s configuration and the large diameter of the radiating elements contribute to the excellent bandwidth of the antenna system, and also inhibits corona discharge.

The horizontally polarized horizontal plane azimuth pattern of the SHPX series antenna is omnidirectional within ±2 dB when the antenna is pole or LAMBDA™ Optimized Mounting System mounted atop a tower. Side mounting the antenna on a typical tower structure will affect the azimuth pattern. ERI offers a pattern measurement service to assist in determining the effect of the mounting structure on the antenna’s pattern. Using ERI’s pattern optimization service, the pattern’s circularity may be improved through the addition of parasitically excited elements.

Feature/Benefits

  • Low VSWR, superior VSWR band width, and minimal weather related VSWR problems
  • Fully pressurized, internal feed and welded feed connections
  • High input power capacity
  • Modular construction facilitates easy installation and repair
  • Rugged brass construction and stainless steel support brackets and hardware – Corrosion resistant construction
  • Radomes or deicing heaters not normally required for radial ice less than 1/2-inch; however radomes or deicing heaters are available
  • Quarter Wave Stub included

Type Number Definition

a - b c d e - f - g - h
  • a
    Model: SHPX | MPX | LPX
  • b
    Number of Bays
  • c
    Interbay Line: Size A = 3 1/8 inch | B = 4 1/16 inch | C = 6 1/8 inch
  • d
    Input Feed Configuration: E = End Fed | C = Center Fed for even number of bays, off center fed for odd number of bays
  • e
    RF Input Size ("SHPX A" Series only): Blank = 3 1/8 inch | 6 = 6 1/8 inch
  • f
    Design Note1: Blank = Omnidirectional | DA = Directional Azimuth Pattern
  • g
    Design Note 2: Blank = Full wave length bay to bay spacing | HW = Half wave length bay to bay spacing
  • h
    Design Note 3: Blank = Standard Product | SP = Special Design
  • Example
    SHPX-4AC-HW
  • Description
    ERI Model SHPX ROTOTILLER FM Antenna, four bay, 3 1/8 inch interbay line, center fed, half wave length bay to bay spacing

Options

  • Anti-rotation brackets
  • Quarter wave stub - Included with SHPX, MPX, and LPX antennas
  • Beam tilt (center fed antennas only)
  • First null fill (center fed antennas only)
  • Second null fill (center fed antennas only); Second null fill not available for LPX antennas
  • Beam tilt and first null fill (center fed antennas only)
  • Radomes
  • Deicers
  • Stem heaters
  • Export packing

Related Publications

ROTOTILLER®X Series FM Antenna Product Brochure

Download File

The ROTOTILLER X Series circularly polarized FM (88 – 108 MHz) antenna combines the exceptional engineering features of an internally fed, fully pressurized system with superior fabrication characterized by totally welded feed connections, rugged brass material and TIG welding. The ROTOTILLER X Series is available in low, medium, and super high power versions and is suitable for single frequency or multiplexed applications.