ttAmerica RoadsterAWD

Any legal types out there? I know many sport car owners whom do not have the front license plate because of aerodynamics, obstruction of airflow into radiators, oil coolers etc.,

Question is, does anybody have any anecdotal info, personal experience, hunches regarding how difficult it is to effectively and accurately radar the front without the license plate?

Interesting observation: about 2mos ago I got popped going 80mph in a rural part of Texas (going to Laredo) at about 3a.m. I was in my Toyota Tundra-no front license plate and an added bumper guard (for the deer). Everything pitch dark when suddenly out of nowhere there's a cruiser with christmas lights on my rear. He approaches my truck from the passenger side, continues to the front, as if he were flabbergasted, then comes to the passenger side window and asks me what happened to my front license plate...."duh......I don't know officer, guess it fell off?". From this I gathered he was unable to "get me" with the radar, so he had to pace me. Lesson learned?: pay the fine and don't wear front license plate-at least on my Tundra.

Tonight was cruising some twisties when an old truck had three other vehicles going 40mph for about 2.5miles. I was right behind this truck and when a straight away appeared I accelerated around him just in time to take a rather cautious right bend. It was just after this bend that I saw a fellow officer sitting waiting for a speeder. Ok, get this.....he had me clocked at 90mph!!! There's no way I was near this and I have learned to immediately glance at my speedo just to varify....was going 62mph just as i was slowing down for the turn. Interesting, he followed me for about a mile before he put on his christmas lights. Was he questioning this number? Could it be accurate?

I told him politely there is no way any sports car can do that turn at 90mph. He must think our cars defy physics. I had him scratching his head..."well, that's what my radar clocked you at". I think deep down inside he knows it's not right. Oh well, Then I remember.....Hey, I don't even have a front license plate!

Lesson learned?: NO contest, pay the fine, life goes on.....fighting this will be too lengthy and not worth the hassle. Such is life I suppose.



Jaime

C H

Front license plates have no bearing on radar or laser. For radar they are measuring the time it takes for the energy the radar is sending to bounce back. Basically the largest object will return to the radar to be calculated. Hence you could use a semi to "block" a radar if you are in its radar shadow. Laser is much more percise and a beam is aimed directly at a vehicle and the officer knows who is speeding since he is aiming the gun right at the car.

C H

BTW when a cop follows you, especially in a nice car, they are running your plates and watching how you drive. It might be worth fighting the ticket if you think he is wrong. You can question the last time the gun was calibrated and if the person who did the work is qualified and so on.

ttAmerica RoadsterAWD

Hi CH. You are exactly right about the bounce back "doppler". License plates is what usually is used to aim at and get a doppler from it. Got a buddy in Cali whom is a CHP. He tell's me they aim at the front license plat since it should be a flat vertical surface. Any angled surfaces bounce the signal at an angle directly proportional to the "incident" angle. This is how the Stealth bomber operates. it has multiple variable angle surfaces, hence no direct bounce back doppler to detect.

So, just wondering if the front surface, without a plate, is too small to accurately doppler back a signal.

Jaime

dougn

a cops radar has a range that depends on your cars radar cross section. this is a measure of how well your car reflects the incident fields from his radar. the greatest contribution to radar cross section of most cars is the radiator ...so I'm told...so in the case of a 964, a liscense plate may make a difference ...but I doubt it. supposidly, a corvette of the mid 80's had a low cross section due to a tilted radiator. fact is a lot of factors come into play for an accurate measurement. the radar needs to be calibrated etc....

chancecasey

The plate does have some effect, but nothing that will make any difference to the gun operator. If the gun is dead ahead, a reasonably flat plate will reflect more energy per area than the rest of the car since it is one of the few surfaces set up to reflect perfectly tangential radiation directly back at the source, give or take. Most of the frontal projected area of the car is composed of material at an angle that would not, for the most part, reflect the radiation back at the source.

The devil, however, is in the little imperfections of all surfaces. While a hood for instance looks like it would not reflect anything back to a radiation source directly in front of the car, under a microscope you see bits and pieces of the hood that do in fact "face" directly forward. That's what the radar receiver is calibrated for, a very minute percentage of the energy density that is transmitted. That's how a radar will get a signature regardless of the angle of the surfaces it is illuminating. I've read that super high-tech materials in the stealth bomber include VERY flat surfaces set up at angles that deflect radar transmission, but 1. I just read it, may be b.s. and 2. no surface is perfect, so SOME reflection back to source will occur. Maybe if it's not b.s. the amount reflected is below an ambient noise level. Needless to say we won't be seeing such tech on cars anytime soon.

In the VERY unlikely case that the radiation source is at a perfectly tangential angle to the front license plate, the energy level received by the gun may in fact be significantly higher than if the car did not have a plate. Not having a plate in this very unlikely circumstance, however, is not going to be "less enough" energy reflected to make any difference to the gun. You're cooked either way.

Of course, all of this is just a convenient approximation of the average result of countless quantum events that behave nothing like what I've described, but that would be extremely off-topic and honestly I don't remember the math to prove it. Just thinking about it makes my head hurt.

ttAmerica RoadsterAWD

Hi Chance. Agreed. For officers whom have a gun on them and are aiming, they can essentially "pop" you even if at that particular time the gun malfunctioned. Per my friend the CHP, they are able to apporximate a velocity. In my case, however, there was no gun..just the stationary rear doppler fixed on the patrol car.

ps. Maybe I should brush up on Heisenberg's principals of uncertainty and question on a molecular/physical level the merrits of electromagnetic fields at various levels...Huh, what did I just say??

Jaime

Toddimus

Since I'm just sitting here, I've gotta pipe in as well. I was a physics major, so I should know more about this than I do. I'll give it a shot though...

I bet the 964 does have a pretty low radar cross-section. Radar is actually a pretty long wavelength signal, I think. On the order of a centimeter or so?

Because of that, I think you need a pretty big reflective surface (like at least 10x the wavelength's dimension) to properly act as a "mirror" for the radar waves. If you don't get the whole wavelength to fit on the surface, then you don't get a good, coherent reflection. The radar waves are not tiny, not huge, but just about right to reflect off of a car's body or plates. The license plate surely can't hurt the reflective properties of a car, and thereby make it easier to detect a radar return.

Seeing as though the 911 doesn't really have any surfaces perpendicular to the direction of travel of the radar beam, it shouldn't really bounce much back towards the source. There is a small oil cooler and AC condenser behind the bumper up front, but they're facing the wrong direction to hurt much. This is a principal of the stealh technology mentioned by chancecasey above. Actually, I've gotta be nit-picky... chancecasey, you said "tangential" to the surface, but I think you meant "normal" to the surface. Tangential is how a curve barely intersects a line or a plane at a point, while normal is a direction or vector exactly perpendicular to a surface or plane. Sorry, I don't really mean to be a pain, or sound like a know it all

You're making me want to take off the front plate. Has anybody in California had trouble from CHP without their front plate installed?

Cheers, happy Friday

ttAmerica RoadsterAWD

Ok, so it seems reasonable that our cars have a low "reflectivity". Next question is: Any possible explanation as to how he got 90mph?

About 30yrs ago there were some MIT students whom managed to foil radar by constructing a twirling three-axis planes, ie, like what you see in a wall corner, ie, the floor plane, the left wall plane and the right wall plane. Imagine this, twirling around the antenna as you drove.

Now, it so happens that when this is twirling, it somehow amplifies the doppler, and the officers would get ridiculous dopplers in the order of 300-380mph. This cannot stand in court, so it was win for the MIT'rs. Could there be something on our front surfaces to act as a twirler? Or, he DOES have a problem radar??

Jaime

dfinnegan

Ever consider that the office may not be telling the truth?

I had got pulled over a couple of months ago and the office tried to "talk" me into a ticket. Said he had me at 83 mph. I knew he did not because I was not going 83. We had a bit of a discussion and he "let me go". I believe he was trying to get me to say something like "I wasn't going 83 I was only going XX!" I didn't bite. This was the second time in about six years that the same exact thing happened.

Also, if you honestly don't think that 90 is doable in the turn then it seems an iron clad defence.

Go to court. Chances are the office won't show up and you win by default.

Best of luck,
Dave

botoo

Since it is illegal to run without a front plate in Wisconsin, they will stop you every time.

jeff522

from what you have posted you should go to court.You may still get find but at a much reduced speed.Many states and ins comp will give more points on your DL for higher speeds.Are cars are good but they still have to follow the laws of physics.

Car and Driver has had some great stories on both radar and lasar.I learned alot from them.They talk to cops,makers or radars,and the makers of the detectors.You can read them on thier website.Here is some of what I've retained.The radar beam gets very wide as it travles.Wife enought that it can cover multiply lanes at typical distances.These are not the greatest radars.They are cheap and less focoused.We have all seen the tree clocked at 90 mph,that's why.Its also why radar detectors work,and lasar with its tight beam is so deadly.When the gun is fired radar waves go everywhere.Trer is also a lot of beams being reflected at all angles,bouncing around all over the place.
While the front plate is a good reflective target,its not the best.The reason Johnney Law fires at the plate is its in many times the center of the car.I live only a few miles from Ok.Ok dose not issue a front plate,but the Highway Patrol has no problem finding speeders.In fact they seem rather good at it.The headlights are one of the brest reflective surfaces,and we shure have headlights.Metal is better than plastic or wood at bouncing back radar.( England's Mosquito fighter/bomber in WWII
was all wood except the engines and a few other parts.Radar had a very very hard time finding her.It was truly the first stealth plane.)Nonmetal objects will absorbe some of the single rather than bouncing it back.This is why stealth aircraft are coated with a top secreat material.A car bra wil reduce a cars reflect nature,so will retracting headlights.The reason the DPS guy could not get a read on your truck was its super reflectivaty.With all that rounded metal up frount bouncing the beam all aroud the front of your truck he got mutipul ruturns.The detertor got to many beams back at different times to figure a speed.Its like an airplane dumping chaft to mess up radar.

chancecasey

Yes, normal not tangential. I too was a physics major but I dropped out of school to play golf, drink whiskey, and chase boogar. Finally graduated 10 years later with a computer "science" degree.

I think everyone agrees that not having the plate isn't going to help enough to make a difference. As far as other strategies, I think jamming would be the most practical though I'm not sure what the effect would be without knowing more about the gun. As far as going to court - in some places you can go to trial and question the last time the gun was calibrated, insist on seeing the paperwork for the calibration, insist on seeing the paperwork for when the officer was trained to use the gun, etc. They will dismiss the case because they can't produce that kind of evidence, or it's very time-consuming, and puts you in a good position in front of a jury. An experienced trial attorney here in CA tells me that tactic doesn't work in this state. I know that 10+ years ago a good attorney could get you off most tickets in TX for $200. Not sure what they did. If you're not sure about your state, call an attorney - you really can't spit without hitting one in this country. Worth a call - most will be straight up about what they can do - and if it's only 2 or 3 x the ticket fine it's worth it.

If you have the time you should definitely fight something you disagree with, but as others have said, you are at the mercy of the integrity of the officer.

Indycam

I read a test done many years ago , how close a car had to be to be clocked by a radar gun .
A big old truck was easy to read from far far away ,the little fiberglass lotus was very hard to clock untill it was right up to the gun . Anything that cuts down the signals return makes it harder for the gun to read your car , you get more time to pick up the fact that you need to slow .

Myth busters did a show on gismos to fool radar , spinning things etc , nothing worked .

ttAmerica RoadsterAWD

Yeah, I like myth busters. I once owned a "phantom" lazer/radar scrambler. Had it on my 944t...got a ticket within the week I bought it. Sent it back. Lesson learned?: pay the fine and stick to educated deductive reasoning. It's just not possible to scramble anything in the civilian market.