Does having my radar transmitting make me more visible to others with radar?

[KiwiKen]

Originally Posted by atlantical

I see someone has had a go at answering that question. its a bit more complicated than that though. During the Falklands war, Argentinian pilots flew with there radar switched off, (when on final approach to targets) but they had radar detection, When the red light went on in the cockpit, they dropped lower, until it went off, eventually they were at sea level, then they released there exocet, the british ships couldn't see them, because they detected the radar transmission from the ship, then avoided it, and the british ships couldn't see there radar because it was switched off.
I don't know the full ins and outs. but if you decide to go in stealth mode, switch off your radar, it can get picked up, thats how they bombed the Iraq radar stations, bombs that home in on the radar transmission.

Many military aircraft have S-X band Radar Detectors and Homers to warn of active enemy Radars, and also to alert for the release of Radar acquisition missiles ( these home on an active transmitting radar - the Exocet that sunk the Sheffield had this facility), similarly warships have radar detection receivers for the same purpose. Transmitting Radars have a specific signature that allows the receiver to determine the type of Radar transmission and whether it is friendly or potentially hostile - this is in addition to IFF Radrs that work on a transponder basis.

Years ago yachtsmen could buy a useful piece of kit called a radar "Watchman" that detected incoming Radar signals from a transmitting vessel and sounded an alarm to warn the yachtsman of an ship in their vicinity with an active radar.

[Snowpetrel]

On the container ships mid ocean without a ship in sight occasionally the classical spiral interference pattern would turn up. As often as not half an hour latter the ship that caused the interferance would pop onto the screen. But only a small percentage of ships would trigger this. Here is my (possibly flawed) understanding of the reason.

The x band 3cm radars run on 9410 mhz (from memory..) +-30 mhz. So there is a small random chance that a ship may have a radar that is tuned to a similar frequency. In this case the pulses are so powerful compared to the receivers sensitivity that they will be received (and transmitted) through the antennas side lobes as well as the main beam.

Interference rejection works in a few different ways. Mostly they had no side effects, but occasionally they could wipe out racons (eg limiters), or fast moving targets (eg pulse to pulse correlaters).

Back the days before AIS you would sometimes encounter a ship or fishing boat that would key its vhf mic every so often at sea. This used to get the watchkeepers attention, as the unexpected loud click on the VHF was unusual. I once clicked back and got a click as a reply, so there was someone listening at the other end just over the horison.

[a64pilot]

I thought ships were S band and we were X band?

Longbow Radar is Ka band, and I tried messing with the MP's traffic Radar, but it never bothered one even a little bit.

We had a Radar jammer that I'm sure would have messed one up, but it wouldn't trigger on traffic Radar

[El Pinguino]

Originally Posted by a64pilot

I thought ships were S band and we were X band?

Longbow Radar is Ka band, and I tried messing with the MP's traffic Radar, but it never bothered one even a little bit.

We had a Radar jammer that I'm sure would have messed one up, but it wouldn't trigger on traffic Radar

Merchant ships tend to have both 3cm ( the small scanner ) and 10cm ( the big scanner ) these days.

[transmitterdan]

There was once marketed a device called CARD. This device listened for ship radar signals and told you the approximate relative bearing of the other ship. They are not much used today. So if another boat has a CARD your radar will light up their box. We have one installed by the PO. It works great.

[a64pilot]

This is what I was talking about, I am sure there are others, likely better ones
http://www.defender.com/product.jsp?...118&id=2025506

I would like to know how effective it is though, be real easy for it to show your return as large as a steel ship. Reflected power that is returned to a Radar is a tiny, tiny fraction of power that it sent out, so something like this would not have to be very powerful at all.

[IslandHopper]

Originally Posted by a64pilot

This is what I was talking about, I am sure there are others, likely better ones
EchoMax Active XS Band Radar Reflector Kit

I would like to know how effective it is though, be real easy for it to show your return as large as a steel ship. Reflected power that is returned to a Radar is a tiny, tiny fraction of power that it sent out, so something like this would not have to be very powerful at all.

Very effective.

All our new build ships fitted with Fast Rescue Boats have them as standard instead of the relatively useless passive reflectors, the older FRC's are having them retrofitted to...

They are also mandatory equipment for all vessels entered in the Golden Globe race...

And here's mine, yet to be fitted...

[KJThomas]

WW2 radars were mostly directional. Scanners turned manually. They could be pointed at each other. Certainly radars receive other radars pulses on the same frequency. Modern radars are set to reject other radar signals.
Radar responders SART's, are mandatory distress equipment on SOLAS ships, to allow easier detection by searchers radars.

[Snowpetrel]

Originally Posted by El Pinguino

Merchant ships tend to have both 3cm ( the small scanner ) and 10cm ( the big scanner ) these days.

Yeah 3cm generally gives way better definition due to smaller horizontal beam width (HBW). 10cm is mostly used for heavy rain and long range detection and even with the bigger scanner still has much worse HBW.