P 300/350 Series Vertically Polarized FM Antenna

Antenna arrays of six (6) bays or less are fed at the bottom bay through a six (6) foot matching section. Nine (9) or more elements are center fed through the six (6) foot matching section piece and a coaxial “T” connector. If the support structure has a large face dimension, several P-300/P-350 dipoles may be mounted around the periphery to obtain 360° coverage. This configuration would be fed in parallel by individual, equal-length feed lines from a power divider. ERI recommends a tower/antenna analysis if this option is employed.


  • Product Line:
  • Product Series:
    300 and 350 Series
  • Frequency Range:
    88 - 108 MHz
  • Multiplexed Versions Available:
  • Broadband Applications:
  • Polarization:
  • VSWR at Input:
    1.07:1 or less (with field matching)
  • 1.25:1 or less (with top pole or LAMBDA™ Mounting System)
  • 1.50:1 or less (top mounted without field matching)
  • Maximum Power Rating:
    120 kW

The P-300/P-350 vertically polarized FM dipole antenna may be used as a single element where a vertically polarized only orientation is desired or may be used in combination with any type of horizontally polarized antenna system.

The P-300/P-350 antenna consists of a large diameter radiating dipoles and interconnecting transmission line sections. The dipoles are electrically and mechanically identical. Each element is spaced one wave length apart with a coupling rigid transmission section. The input port to the antenna is a standard EIA, 50 ohm flange. When used in combination with horizontal elements the system is furnished with suitable power dividers and impedance matching networks between elements.

The P-300/P-350 dipole is a broad-band radiator (low Q) which minimizes cross-coupling between main and subcarrier channels. The P-300 dipole is fabricated from 85/15 brass which has excellent mechanical and electrical properties. This antenna is rugged, light-weight, and presents low wind load forces.

The P-350 vertically polarized FM dipole antenna is a higher power version of ERI’s well known P-300 dipole antenna. Using the same quality materials and manufacturing process that has been used for decades, ERI has modified the design only by increasing the power handling capability of the individual elements. The single bay input power rating has been increased to 10 kW for the Series A and Series B dipoles, and 56 kW for the Series C dipoles. Multiple elements may be used to increase power gain and allowable input power levels. Null fill and beam tilt are also available.


  • Low VSWR, superior VSWR band width, minimal weather related VSWR problems
  • Fully pressurized, internal feed, welded feed connections, series fed radiating elements
  • High input power capacity
  • Modular construction facilitates easy installation and repair; Custom modifications are available
  • 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 and deicers are available
  • Custom designed antenna supports

Ordering Information

Type Number Definition

a - b c d
  • a
    Model: 300 | 350
  • b
    Number of Bays
  • c
    Input Power Rating: A = Low Power | B = Medium Power | C = High Power
  • d
    Input Feed Configuration: E = End fed | C = Center fed
  • Example
  • Description
    ERI Model 300 P Series FM Antenna, twelve bay, medium power, center fed.


  • Anti-Rotation Brackets (per bay)
  • Quarter wave stub (per system)\
  • Beam tilt (per system) [center fed antennas only]
  • First null fill (per system) [center fed antennas only]
  • Second null fill (per system) [center fed antennas only]
  • Radomes
  • Export packing (per bay)

Mounting Information

Each antenna mounting bracket is designed and fabricated to match the tower and mounting specifications of the purchaser. The antenna can be side or pole mounted. Custom designed and fabricated antenna support poles and tower sections are also available from ERI. The horizontal radiation pattern of the P-300/P-350 dipole is omni-directional in free space. The extent of deviation from a circular pattern will vary with the type and size of the supporting structure. For the best possible circular pattern we recommend the antenna system be mounted on an ERI antenna support pole. Structural design information is required if the P-300/P-350 system is to be placed on another manufacturer’s support structure.

Utilize the ERI Advantage

Combine an ERI antenna with an ERI Mounting Structure, Pattern Measurement and Installation. Assure yourself of the best antenna/tower interaction. ERI’s Pattern Measurement service will provide the crucial answers concerning the relationship between the antenna mounting orientation and antenna pattern.

ERI Mounting Sections are designed to achieve optimum antenna performance while reducing weight and wind loads. Only ERI can offer you an antenna/tower/installation package that will achieve your highest expectations in a demanding FM market. Contact Electronics Research for complete electrical and mechanical specifications.

Related Publications

P 300/350 Series Vertically Polarized FM Antenna Product Brochure

Download File

The P 300 and P 350 Series vertically polarized FM (88 – 108 MHz) antennas may be used as an element array for vertical only polarization or in combination with a horizontally polarized antenna to achieve circular or elliptical polarization.