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Microwave leak detector
Any radar experts?
I was wondering if a Microwave leak detector could be 'doctored' for use as an 'S' band radar detector for use while cruising. They are pretty sensitive but would possible need some type of antenna and also I don't know if they could cover the actual band width used by ships's radar. They would also need to set-up with an alarm. For example, one I looked at for $49.oo Sensitivity to a wide range of frequencies Calibrated at 2.4 gigahertz, which is the operating frequency of microwave ovens Sensitivity down to 0.01mW/cm2 at 2450MHz. Reads up to 9.99mW/cm2 in hundredths of mW/cm2. What do you think? Cheers, Jim |
Microwave leak detector
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Microwave leak detector
wrote in news:fb2cbd4c-164a-4c0f-aee9-2ef93949e881
@d4g2000prg.googlegroups.com: What do you think? Useless. Wrong band! Boat radars are on X-band (or what used to be X- band). They operate on 10GHZ....WAY too far from 2450 Mhz microwave leak detectors. You'll be fine if you don't put your gonads right up against the feedhorn or planar panel and hold it. AVERAGE power of a boat radar is TINY....very narrow pulse width to get fine resolution returns....long rest times to hold down the battery drain current. http://www.furunousa.com/Furuno/Doc/...FODH2N7B/1715% 20Brochure%20b.pdf This 2.2KW PEAK output Furuno uses 38W of power at full display brightness and power output. Of that 38W, most of it is display lighting and magnetron filament heating up the maggie. It's AVERAGE (heating) output power is probably around 2W, tops. Rotating properly, you'd have to put your nose up against the radome for 20 years before your first cataract operation. ANY cop hiding his 24GHZ CONTINUOUS WAVE doppler radar bouncing off the lead glass windscreen of his cruiser is in FAR FAR more danger of RF than you could ever be. ---------------------------------------------------- Now, I used to play with this radar my rich uncle bought me: http://en.wikipedia.org/wiki/AN/SPS-49 If you had any brains, you didn't go anywhere near its antenna while it was on. It cooked seagulls right out of the sky!...(c; |
Microwave leak detector
In article ,
larry wrote: Useless. Wrong band! Boat radars are on X-band (or what used to be X- band). They operate on 10GHZ....WAY too far from 2450 Mhz microwave leak detectors. Well, not quite right, but close. There are a number of S Band Marine Radars in use, and available, worldwide. They are mostly used on ships LARGER than 1200 Tons, and used as Weather Radars, and Long Distance Position Fixing. Larry is correct, in that MOST Consumer and Small Ship Radars, are X Band, and your detector wouldn't see ANY of those. Bruce in alaska -- Bruce in alaska add path after fast to reply |
Microwave leak detector
Bruce in alaska wrote in news:fast-151579.10373820012008
@netnews.worldnet.att.net: They are mostly used on ships LARGER than 1200 Tons, I figured most of these boys and girls were on plastic bubbleboats and didn't have 8MW air search radars aboard....(c; |
Microwave leak detector
In article ,
John Navas wrote: http://www.sea-me.co.uk/ ... BTW: Do these (active reflectors) also work if you have your own radar, ie will they make you visible to other vessels? Or is it only possible to use passive ones (90? reflectors, Luneburg lenses)? Never quite figured that out in spite of my MSEE degree :-) Marc -- remove bye and from mercial to get valid e-mail http://www.heusser.com |
Microwave leak detector
On Mon, 21 Jan 2008 01:06:06 +0100, Marc Heusser
d wrote: In article , John Navas wrote: http://www.sea-me.co.uk/ ... BTW: Do these (active reflectors) also work if you have your own radar, ie will they make you visible to other vessels? Or is it only possible to use passive ones (90? reflectors, Luneburg lenses)? Never quite figured that out in spite of my MSEE degree :-) Marc It appears from the user handbook that the thing is a radar transponder - on receipt of a signal in the appropriate frequency range, it will transmit a brief pulse on that frequency, which will appear as an obvious mark on the radar screen, just like a RACON. It is independent of your own radar - but must be mounted so that it will not be triggered by your radar. -- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca |
Microwave leak detector - active radar reflectors
In article .com,
Peter Bennett wrote: On Mon, 21 Jan 2008 01:06:06 +0100, Marc Heusser d wrote: In article , John Navas wrote: http://www.sea-me.co.uk/ ... BTW: Do these (active reflectors) also work if you have your own radar, ie will they make you visible to other vessels? Or is it only possible to use passive ones (90? reflectors, Luneburg lenses)? Never quite figured that out in spite of my MSEE degree :-) Marc It appears from the user handbook that the thing is a radar transponder - on receipt of a signal in the appropriate frequency range, it will transmit a brief pulse on that frequency, which will appear as an obvious mark on the radar screen, just like a RACON. Yes, so much is clear. It is independent of your own radar - but must be mounted so that it will not be triggered by your radar. That is most likely impossible. At a few kW of transmitting power (peak), it will trigger when the distance is only a few metres at most. The question is, whether it still appears on other radars. Marc -- remove bye and from mercial to get valid e-mail http://www.heusser.com |
Microwave leak detector - active radar reflectors
On Mon, 21 Jan 2008 08:49:02 +0100, Marc Heusser
d wrote in : In article .com, Peter Bennett wrote: It is independent of your own radar - but must be mounted so that it will not be triggered by your radar. That is most likely impossible. At a few kW of transmitting power (peak), it will trigger when the distance is only a few metres at most. Marine radars have a limited vertical beam width, and the transponder should be mounted above or below that vertical pattern. See the Handbook: If Sea-me is being fitted elsewhere, say on a radar arch, ensure that it is above the superstructure of the vessel and that it is not within the vertical beamwidth of any radar which may also be fitted. Normally this means that the Sea-me antenna unit must be above or below a 30° line from the centre of a radar antenna but you will need to refer to your radar manual to confirm this. .... Radars have many leakage paths and so Sea-me will respond to your own radar’s pulses (typically a pulse is 1 microsecond long and is repeated every 1 millisecond). The LED flash has been extended to 100 milliseconds to make it visible to the human eye and so it will be permanently on when your own radar is transmitting. However Sea-me transmits in response to an incoming pulse and so it will respond to any which arrive in the spaces between the pulses put out by your own radar. Typically the ratio of space to pulse is 1000:1 and so there are 999 microsecond spaces for every 1 microsecond pulse received, plenty of time for others to get in, even when electronic recovery time has been allowed for. This effect does however mean that Sea-me, because the active light is on, will be unable to tell you that you are being struck by another radar. If this is a concern then you are advised to switch your radar into its standby mode when you are not actually using it. You probably do this anyway in order to save power. -- Best regards, John Navas http:/navasgroup.com |
Microwave leak detector - active radar reflectors
John Navas wrote in
: Marine radars have a limited vertical beam width, and the transponder should be mounted above or below that vertical pattern. See the Handbook: WRONG! Geez, John.... Marine radars have limited HORIZONTAL beamwidth so you can see 3 targets kinda close together as 3 targets, not 1 blob. They have WIDE VERTICAL beamwidth so they are pointing at the horizon EVEN WHEN THE BOAT IS HEELED OVER OR ROLLING! If they had narrow vertical beamwidth, the only time you'd see the target is in flat water or at the marina dock! |
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