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Echomax was formed in 1998 following the purchase of John Firths third patent which was based on a revolutionary symmetrical three stack twelve corner array. When viewed from the horizon there is a fully open orthogonal corner facing you and one about to open or close. 

Since then our radar reflectors have become one of the best known passive radar reflectors in the world. From early sales to pleasure vessels they are now fitted by many of the leading buoy manufacturers in Europe, Australia, USA,  Canada, Port and Harbour Authorities world wide. Many foreign Navies including US Nuclear Submarines, The Dutch,French,USA, Danish, Swedish, UK Navies and others use Echomax.

In 2014 The Canadian Coastguard chose our EM400 for the top mark in their latest batch of 300 buoys. They confirmed that their sea trials proved everything we had claimed for the product. After a years sea trials the US Nuclear SubPac fleet carry an EM305PE on board for enhanced radar visibility when surfaced as required.

We have tested arrays from 100mm to 500mm in one, two or three stack configurations in the QinetiQ Anechoic Chamber at Funtington and are in a position to make custom made radar reflectors that not only fit a given top mark space but that give a proven response. When we entered the radar reflector market it was considered a "Black Art" as no one really knew what they were buying or what response the reflector gave.  We decided then that we would test each and every product we offerred for sale and believe that we are the only manufacturer of radar reflectors in the world who freely publishes the QinetiQ Anechoic Chamber test results of every product we offer for sale on this website so that everybody knows exactley what they are buying. Arrays are made in aluminium or stainless steel as required.

Our EM230 -230BR have Ships Wheel Mark certification to ISO 8729-1997 for Life Boats and Rescue Craft and copies of the BABT - TUV Module B and D Audit. The inflatable EMA03i carries SOLAS certification for liferaft use, certificates can be downloaded from this website . We are able to advise and offer a solution for any one who wants to use an efficient radar reflector on their vessel, buoy or land - sea hazard.

In 2010 we introduced the Active-X Radar Target Enhancer followed in 2011 by the Active-XS dual band version which meets ISO 8729-2 . The Active X was fitted by the Clipper Around The World Race Yachts 2010-11-12 and the Active XS to 2012-13 with complete reliability. This is now accepted as the best RTE in the world- see PBO sea trials report using the link on the Active X products entry.

  • Upgrade existing buoys using passive or active radar reflector technology

  • Upgrade existing floating navigation, land or Marine Hazard markers

  • Offer Passive and active RTE systems and custom made radar reflectors from 1M2-500M2

Our new range of Trihedral Target Corner reflectors introduced in 2015 have already created demand from the Armed Services, Satellite and Space technology Industries. 

john firth.jpg
firth and knox-johnson.jpg

Echomax Radar Reflectors are based on an invention by John Firth.

Concerned about the performance of radar reflectors John Firth spent forty years of his life improving their design. As a member of the ISO committee in Paris in 1980, considering amendments to Marine Radar Reflectors Regulations, John drafted performance paragraphs subsequently incorporated into ISO 8729. He obtained three patents and was one of the founder members of Firdell Multi Flectors and his first patent was used in the Blipper-210-7. His second patent was an improved design which was sold as the Gillie-Firth for 30 years.  In 1998 we purchased John Firths third patent which was a revolutionary design of the stacked array principle and called the product Echomax.

For many years the Octahedral reflector has been accepted as the basis for the ISO 8729, RORC and ORC specification. However, at a 15° tilt its serious failings are a lack of response over 140° azimuth

"Comparing Echomax to other reflectors is like comparing a car headlight with a candle in a jar."

"My involvement in radar reflectors was merely self preservation - as I was the target!"


Echomax Reflectors

Echomax EM230 weighs 2.3kg and comprises twelve identical sectors each responding with peaks to 24M2, 10M2 - 70%, 5M2 - 100%. When used in real sea conditions the reflector is tilted, with yaw pitch and roll, 'glint' also ensures an all round performance is maintained.

Comprised of a three stack array of laser cut aluminum or stainless steel enclosed in a Polyethylene case. At each end 8mm diameter fixings enable a halyard hoist, mast or deck mounting. Echomax inflatable reflectors fold down into a neat pocket size, and are a wise addition to any emergency grab bag.

Radar Reflectors explained

Radar Cross Section (RCS)

1. A sphere operates with a weak signal at all angles of incident radiation.

2. A flat plate is an extremely efficient reflector but has a very sharp angle of response.

3. RCS may, for practical purposes, be defined as the cross section area of a conducting sphere of such a size that it would return an echo equal in strength to that of an equivalent flat plate oriented so as to be perpendicular to the direction of the incident radiation.

4. One metre squared is the cross section of a sphere radius 0.565 metre (R2xPi - 1 metre 2)

Radar Interference by Sea State & Precipitation
Mariners Handbook Fourth Edition 1973

'Sea' is the name given to waves generated by wind blowing locally. A radar screen becomes cluttered when echoes from waves are received. Further clutter arises from precipitation (rain, snow, and fog)

sea states  wave clutter.JPG

Fog is caused by the cooling of air in contact with a surface at a temperature whereby it can no longer maintain, in an invisible state, the water vapour which is present in it. Condensation of the vapour produces minute, though visible, water droplets. Rain and snow are further examples of droplets which return radar clutter.

Transmitted power, to and from the target, is attenuated by precipitation on average by -5dB (-70% of reflected power). Visibility will be a guide to assessing power RCS lost.

Note:- Precipitation and wave clutter may or may not occur together.

assessing power.JPG

The mandatory collision frequency is 'X' band. Precipitation is penetrated better on 'S' band but its target response is 1/10th 'X' band. S Band does not overcome sea clutter but may be used from beyond three nautical miles to penetrate fog, rain, snow etc. A 10m2 target will return 0.001 m2 from ten nautical miles. Doubling the distance requires target area to be16 times greater.

F. J. Wylie 'The use of Radar at Sea'

Sea Force 4 - Wave height one metre.
Sea Force 6 - Wave height Two metres.

Approximate clutter from waves:

Sea force chart.JPG
Octangle radar graph.JPG

F. J. Wylie "The Use of Radar at Sea"

A = Wave height 3 feet (Force 4) 
B = Wave height 6 feet (Force 6)
C = 2nd class buoy
D = 2nd. class buoy with 17" corner reflector
E = theoretical response from an ideal 10sq.m sphere reflector without sea surface reflections
F = statistical limit of effective response
'X' = dips due to sea surface reflections

One of the last faxes received from John Firth shortly before his death.

This has been reproduced from a poor quality fax and we hope we have managed to transcribe it correctly.

Orthogonal Corners (Type T)

Pi x C4 Lambda2 x 4/3 - RCS (corner-lambda in metres)
(‘X’ band lambda 0.032 metre)
Target area sq.m Distance4 – Response sq.m. (area sq.m. – distance in n. miles)
It is difficult to put the science of radar into simple terms but the following may help understanding by small vessel sailors who use radar reflectors

Small vessels radar

(Commercial shipping will have more powerful sets with scanners at great heights).
Power echoed is minute – eg 10 sq.m. at 10 n.miles = power 0.001 sq.m. (-40dB)
Maximum receiver gain is 80dB (x 1000,000,000)
Scanners rotate every 2.31 seconds
Ranges – short 1.5 n.m., medium 24 n.m. long 48 n.m.
Beam width azimuth at range limit is: - short 48 metres, medium 776m, long 44448m.
Transmission pulses on target each scan: - short 19, medium 9.5, long 4.75
When distance between scanner and target doubles echo power reduces by 1/16.

Display paints of modern radars do not spread and may not change brilliance when the echo strengthens, nowhere is echo strength mentioned in the CollisionRegulations”. The reason for yachting press ‘sea trials’ being subjective.

Anechoic chamber recordings accurately define power response over azimuth and vertical angles. Vessel yaw/roll ensures 10 degree nulls in performance are acceptable. The mandatory collision avoidance frequency is ‘X’ band 9Ghz – lambda 32mm. Large vessels use ‘S’ band 3 GHz – lambda 96mm – for its ability to penetrate precipitation (fog, snow, rain) at distances where ‘X’ band may not do so. Scanned at ‘S’ band the target power returned is one tenth that of ‘X’ band. When wave clutter is encountered in the absence of precipitation ‘S’ band offers little advantage over ‘X’ band.

Precipitation attenuation varies considerably decreasing as distance falls.
Conversely target power increases (see examples below)
For vessels such as yachts, 30 sq.m. RCS may be acceptable as a compromise to the 100 sq.m RCS necessary to meet all conditions.

F. J. Wylie’s sea state clutter graph

Target ‘D’ (2nd class buoy – 100 sq.m) at 1.5 n.miles and less is screened by line ‘B’
Target ‘C’ (2nd class buoy – 10 sq.m.) at 1.5n.miles and less is screened by line ‘A’
Due to ‘grazing angle’ increase sea state clutter increases rapidly within 5 n.miles
Within 3 n.miles a 2.5 sq.m. reflector is hidden by wave clutter.
Graph line ‘D’ 100 sq.m (ex sea surface reflection dips)

RCS at:

  • 5 n.miles 0.160 sq.m

  • 4 n.miles 0.391

  • 3 n.miles 1.235

  • 2 n.miles 6.250

  • 1.5 n.miles 19.753

  • 1.25 n.miles 40.960

Corner 8.76” – 0.225 metres 10 sq. m

RCS at:

  • 5 n.miles 0.016 sq.m

  • 4 n.miles 0.03910

  • 3 n.miles 0.1235

  • 2 n. miles 0.625

  • 1.5 n. miles 1.9753

  • 1.25 n. miles 4.0960

Note: Beware of claims overstating performance.
Use the largest reflector RCS available.
Beware of traffic and weather conditions. Your radar echo may save your life
Big ships speed leaves little time to react.

J. H Firth 22nd. April 2002

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