Information Station Specialists is the best known source of travelers information stations, highway advisory radio, advisory signs and services needed to reach motorists with public service information. Learn more about Information Station Specialists.
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Why antenna grounding is important, how it works and is installed.
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Standard Antenna System

Transmitter System

Assuring a Strong Signal
Every agency that has invested in an information radio station wants a signal with suitable strength to achieve the FCC maximum 2.0 mV/m at .93 miles (yielding the typical 3-5 mile coverage radius). The amount of AM signal an antenna system can generate is related to many factors and one of the most important is the antenna’s counterpoise (grounding) and how it is designed and installed. The vertical “whip” portion of the antenna and the buried portion together are responsible for the creation of the station's signal. The buried counterpoise portion is required to "complete the circuit,” making the antenna system an efficient radiator. Therefore, the more robust the grounding, the more efficient the antenna and the stronger the signal at a given transmitter wattage. The physical size of the grounding becomes most important at the longer wavelengths − that is, at the bottom end of the AM band.
Vertical Antenna Grounding Horizontal Antenna Grounding
Vertical Profile Antenna System

The most cost effective and least intrusive antenna grounding method is afforded by the Vertical Profile Antenna System. The active element is comprised of a cylindrical copper sheath attached to the buried portion of the aluminum antenna support pole. The conductive pole and sheath, together create an effective vertical grounding method. Installation costs are reduced, compared to horizontal grounding methods, because the pole and the grounding are one piece, eliminating the need for horizontal groundplane installation and the resulting cost, time and site disruption.


Unirod

For installations where vertical grounding is required but the antenna must be mounted on an existing pole or structure, a Unirod may be employed. The Unirod can be from 10 to 40 feet in length (longer Unirods for long wavelength frequencies) and is augured into the earth beneath the antenna pole, installed with a highly conductive soil backfill. Unirods are also recommended when the most efficient possible grounding method is required.
PowerPlane Factory-Assembled Groundplane



The PowerPlane Groundplane is composed of 62 copper ground radials (12-gauge) bonded to an inner ring of (4-gauge) copper wire. Each radial is actually a loop, and extends outward from the inner ring 10 feet in every direction, creating a circular fan pattern.

At the upper end of the AM band, the PowerPlane should be installed as described. At the lower end of the AM band (below 1000 kHz), efficiency can be increased if the loops are cut to create 62 straight radials, each 20 feet in length.

Install the groundplane in good earth beneath the antenna/pole at about a 6” depth. It may also be installed on the surface of the ground, covered or uncovered. A version of the PowerPlane (FlexPlane) is available for roof surface installation in special circumstances or for portable applications.

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©  1983-2018  • Information Station Specialists, Inc. •  All Rights Reserved
PO Box 51, Zeeland, Michigan, USA, 49464-0051, Phone 616.772.2300, Fax 616.772.2966, Email info@theRADIOsource.com

The USA's best known source for Travelers' Information Stations, Highway Advisory Radio & related products/services.


 Trademarks: 2X Signal Booster, ALERT AM Emergency Advisory Radio System, AP55 Digital Message Player, ENcast Emergency Notification Broadcast System, FAS6000 Flashing Beacons & Controller, FASTrack Quick-Erect Sign, Flashing ALERT Sign System, Free-Radiate On-Premise Radio Broadcast System, HearMoreInfo Internet Broadcasts, i.AM.radio , Information Station Specialists, InfoRadio Format, Information Station Classic, Information Station IP, InfOSpot License-Free Radio Station, IP8 Digital Message Player, IP76 Digital Message Player, ITS6000 Highway Advisory Radio Network, LIGHTNING LED Portable Changeable Message Sign, NX8R Digital Message Player, Potential Interference Notification Services (PINS), PowerPlane Flex  Factory-Assembled Groundplane, EventCAST Portable Information Radio Service, RadioSTAT Portable Emergency Advisory Radio Station, Signal Measurement Radio Receiver, SpotCast Internet Broadcast Service, Stealth Sign, StreamCast Internet Broadcast Service, Stylized ISS Logo, SX200 Watt Meter, Talking House , TR6000 HQ5.0 Transmitter, TR6000 15.73 Transmitter, VP9000 Vertical Profile Antenna System, VoiceStar Portable Highway Advisory Radio Station (with our without Changeable Message Sign), Wireless Audio Link.

Information Radio Stations is a generic term synonymous with Travelers Information Stations (TIS), Highway Advisory Radio Stations (HAR) / Highway Information Systems & Low Power Radio Stations (LPR). Operation of the stations is governed by FCC Part 90.242 Rules. A FCC license is required. Information Radio Stations may be fixed or portable. Subcomponents may include transmitter, antenna and ground system, digital voice player, wateter, cabinet with conventional or Corbin locks, lightning arrestors for RF, power and telephone lines, coaxial cable. Most stations employ black maximized antennas to discourage ice accumulation and security measures to prevent unauthorized program access. Options include synchronization, battery backup, solar power, remote programming by local, network or telco, multi-station audio distribution via RF or LAN / WAN or wireless network.