Horizon TM Model 704 Intermediate Guided Wave Radar Transmitter

The HorizonTM 704 is a loop-powered, 24 VDC liquid-level transmitter based upon the revolutionary Guided Wave Radar (GWR) technology. The electronics of the HORIZON 704 is integral mount on the GWR probe and allows local calibration via a 3 push button keypad / LCD screen.
The transmitter is designed to provide all of the performance advantages of GWR. Available in a nonrotatable, single compartment plastic or aluminum housing, this transmitter offers simple configuration with three push buttons and a 2-line × 8 character liquid crystal display. The Model 704 covers a broad application range by utilizing coaxial and twin rod probes.

Operating Principle

HORIZON Guided Wave Radar is based upon Time Domain Reflectometry (TDR). TDR utilizes pulses of high frequency electromagnetic energy transmitted down a probe. When a pulse reaches a surface that has a higher dielectric than the vapor space in which it is traveling, the pulse is reflected. High-speed timing circuitry precisely measures the total transit time and provides an accurate measure of the liquid level.


Liquids or slurries
Hydrocarbons to water-based media (dielectric 1.7 - 100)
Most process or storage vessels
Bridles and by-pass chambers
Standard process applications
Storage and buffer tanks


Two-wire, 24 VDC loop-powered level transmitter
Low dielectric measurement capability
4.90 m (16 foot) maximum range
IS (intrinsically safe), XP (explosion proof), and Non-Sparking approvals


HART® digital communications
Single compartment cast aluminum or Valox® housing


ATEX Ex i certificate


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