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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 America's Source for Information Radio Systems and Services since 1983
High Performance AM Radio Antenna
Model HPR.0990 Maximum Efficiency Whip Design; up to 270 Watts
HPR Antenna
The HPR.0990 High Performance Antenna
is the heart of the
RadioSAFE System.
The HPR.0990 Antenna’s capacitive
“Top Hat” design maximizes efficiency.
The heavy-duty HPR.0990 Antenna
Coil can handle hundreds of watts.
Insulator Mounts
Insulator Mounts with Standoffs (HP.23)
This high performance antenna offers a communication professional the ability to establish an AM broadcast signal more efficiently than before possible with an antenna of similar design and price point. Its 50-ohm resonant design requires only a matching transformer at its feed-point, eliminating the need for an antenna tuner (matching network). Designed to operate most efficiently in conjunction with a horizontal groundplane, this antenna is compact and light-weight, making it easy to ship, set up and install. It may be assembled in minutes, if required, for an emergency application.  
Frequency Range and Coverage 
Different versions of the antenna's design allow it to function on any frequency in the 470 to 1800 kHz range. Field tests prove that this antenna is capable of handling hundreds of watts, producing a coverage pattern that can exceed 20 miles in radius. 
  • Common users are emergency managers and associated amateur radio operators who want to reach their publics during times when power and other communications and internet services are compromised.
  • Commercial broadcasters can also benefit by using the HPR.0990 High Performance Antenna to keep their AM stations on the air temporarily at low power following calamities.

See examples on the right. - - - > 

Information Radio Station licensees can easily upgrade to the HPR.0990 Antenna. The antenna’s efficiency will allow a 10-watt signal to be produced that is two to four times that of the standard antenna, depending on frequency. A waiver is required from the FCC if an Information Station’s signal intensity would exceed 2.0 mV/m at 1.5 km (0.93 mile) by substitution of this antenna. 
When utilized in association with an Information Radio Station for expanded coverage, i.e., RadioSAFE Wide Area Emergency Radio Broadcast Systems, a waiver and/or an emergency Special Temporary Authority (STA) from the FCC is required. Engineering and filings for the required waivers and STAs can be supplied by Information Station Specialists. 
Specifications (*)     Click here for a printable specification sheet.
  • Power: up to 270 watts carrier (1710 kHz)/100% modulation; up to 180 watts carrier (530 kHz)/100% modulation. See Chart 1 below.
  • Frequency Range: various versions of the antenna's design allow it to function on any frequency in the 530 to 1710 kHz operating range.
  • Radiation Efficiency: 65 (530 kHz) to 308 (1710 kHz) with 50’/32-element groundplane (mV/m/km/1KW IDF – Inverse Distance Field). See Charts 2 and 3 below.
  • Impedance: 10-20 ohms (typical) with 50' tip height and 25-50' radius groundplane (typical).
  • Mounting Format: top of support structure [tower, mast or pole]. Lower 36” of antenna base clamps in insulator mounts which can be attached to a vertical support with a round or flat surface.
  • Type: center-loaded, bottom-fed vertical, whip-type antenna with adjustable 6- element capacitive top hat and adjustable vertical tuning section . Omni directional. Anodized aluminum finish. Guying ring included.
  • Audio Bandwidth (2:1 SWR): 530 kHz: +/- 1.5 kHz; 1710 kHz +/- 5.5 kHz. See Table 1 below.
  • Temperature endurance: -40°C to 85°C.
  • Wind endurance: greater than 100 MPH, unguyed. Greater than 140 MPH with the addition of guy lines (nonconductive only).
  • Weight of the complete antenna varies with frequency. 30.5 lbs nominal. Mounts with insulators (2): 5.5 lbs total.
  • Overall assembly: 5 sections plus capacitive hat. Length varies with frequency and tip extension. Typical: 32'. Includes assembly hardware. Outside diameter of vertical sections taper from 2.5” (lower) to 1.0” (upper). Capacitive hat spoke length varies with frequency.
  • Recommended separation from buildings and structures: 100’ or equal to the height of the structure, whichever is greater.
  • RF exposure separation: 1 meter minimum recommended for both occupational and controlled environments.

(*) Specifications are subject to change without notice. You can download a printed version here.

Optional Accessories
Table 1 of 1 

 Frequency Band

Max Carrier Power
125% + Modulation Peaks

2:1 VSWR Bandwidth

1500 - 1700 kHz

220 Watts

+/- 5.5 KHz

1100 - 1500 kHz

210 Watts

+/- 4.5 KHz

800 - 1100 kHz

200 Watts

+/- 3.5 KHz

650 - 800 kHz

175 Watts

+/- 2.8KHz

530- 650 kHz

155 Watts

+/- 1.5 KHz

Chart 1 of 3
Power v Frequench 
Chart 2 of 3 
 Efficiency Chart
Chart 3 of 3
Typical HPR 0990 Vertical & Horizontal Radiation Pattern

(Feedpoint Elevated on 20ft Pole - 32 Radials [50ft] at Base of Support)
 Related Links
Antenna Comparison Chart
Radio World article: "ISS HPR.0990 AM Antenna Does a Quick Stand-In; Solving a problem for KNBI(AM) in Monterey.Calif." Dec 28, 2021.  
The Source article: "High Performance Antenna Launches a New Era in Information Radio Broadcasting."  
Coverage Map 

From a building roof, the HPR.0990 antenna can produce coverage with 180 watts to 10 miles in radius (the 0.5 mV/m signal contour).

HPR 10 Stories Up 

This HPR.0990 Antenna (left foreground) is installed on a 10-story building in the heart of downtown Indianapolis.


ThThe HPR.0990 Antenna (circled in yellow above) stands in as WJOI Norfolk’s tower is collapsed to make way for a new one.See "Tower Down! Norfolk's WJOI Maintains Operations with Quick Switch to New HPR.0990 AM Antenna," The Source, Sep 2019.

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PO Box 51, Zeeland, Michigan, USA, 49464-0051, Phone 616.772.2300, Email Us

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Information Radio Station is a generic term synonymous with Travelers Information Station (TIS), Highway Advisory Radio (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, wattmeter, 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.