focusing microwaves

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gabreal

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this has bin bothering me for sometime now. correct any and all of this, i'm just trying to learn.

light, microwaves, radio waves and the like are basically electromagnetic energy, so they should display the same properties right? If so, how is it that a laser pointer is focused upon a certain point?

Can microwaves and radio waves be focused to act like a laser beam?

Cheers,
Chris
 
The answer is, kind of. I'm no physicist, but essentially, you can focus microwavs, but because you are doing it from a point source, with waves radiating out, you have to do it like you do a large searchlight or a torch. Whereas with a laser, the light waves come out in a coherent manner, they are all parrallel to each other, something that isnt possible with many of the ways of producing microwaves. On the other hand, you can also generate microwaves in the same way as lasers, thus getting the same kind of parallel waves so that they will burn something from a far greater distance.
 
guthrie said:
The answer is, kind of. I'm no physicist, but essentially, you can focus microwavs, but because you are doing it from a point source, with waves radiating out, you have to do it like you do a large searchlight or a torch. Whereas with a laser, the light waves come out in a coherent manner, they are all parrallel to each other, something that isnt possible with many of the ways of producing microwaves. On the other hand, you can also generate microwaves in the same way as lasers, thus getting the same kind of parallel waves so that they will burn something from a far greater distance.
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That's fairly accurate. I worked with microwaves for a number of years and there are several different techniques which give varying results. The simplest is an ordinary parabolic reflector, such as is found on a dish "antenna" and works exactly like the reflector in a common flashlight.

Another involves magnetic focusing. Since microwaves are simply EM radiation they consist of two fields perpendicular to each other. They are called the E and H fields - for electric and magnetic - and the magnetic part reacts to some degree to an external field. The beam can be rotated, retarded, reflected and made somewhat tighter by manipulation of the external field.

Just keep in mind that even a laser beam exhibits some divergence (contrary to popular misconception) and microwaves will always diverge to a MUCH greater extent regardless of the method used. If you look at a graph of a microwave source, even using the best reflector available, you will see that the pattern consists of four lobes - the forward lobe, two side lobes, and a rear lobe. Even under the best of conditions the rear lobe will contain a full 35% as much power as the forward lobe, and generally more.
 
The problem with focused microwaves is that you'd need an enormous amount of power to make them usefull in supplying energy to people like the electricity we use today supplied by the wires that transmit that electricity to everyone. Those wires loose about 50 percent of the power they started with before they reach the customers. Microwaves would require more energy that they could supply for them to be used for they dissapate over distances just like the conventional metholds but faster.

If you're considering using microwaves as a weapon the same problem happens , you'd need allot of energy to transmit enough power to destroy someone over a mile away.
 
cosmictraveler said:
The problem with focused microwaves is that you'd need an enormous amount of power to make them usefull in supplying energy to people like the electricity we use today supplied by the wires that transmit that electricity to everyone. Those wires loose about 50 percent of the power they started with before they reach the customers. Microwaves would require more energy that they could supply for them to be used for they dissapate over distances just like the conventional metholds but faster.

If you're considering using microwaves as a weapon the same problem happens , you'd need allot of energy to transmit enough power to destroy someone over a mile away.
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Just a wee bit out of date, aren't you? :) Microwave weapons (localized heating) are already past the design stage as are ultrasonic weapons.
 
Utltasonics uses SOUND whereas microwaves uses ELECTRIC energy. There's a difference don't ya know?
 
cosmictraveler said:
Utltasonics uses SOUND whereas microwaves uses ELECTRIC energy. There's a difference don't ya know?
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Of course! Don't YOU realize the phrase "as are" is generally refering to something different than the subject of the sentence??????
 
I realise that now. Still the weapons won't really work that well with all the power they will need to create enough energy to make them effective. A 3 Gigawatt generator would be needed to use the ultrasonic weapon and that would only be useful for under 1/2 mile. Same is true with a microwave weapon, it takes enormous amounts of energy to get them to ne useful at over 1/2 mile. This stuff is all useless for look also at the size of all this plus the generators needed.
 
Microwave weapon? I thought they were most of the way towards getting an anti-crowd microwave based pain inducing beam.
 
The pain inducing beam is supposed to make people "move out of the way" in a few seconds. There are a lot of us who can't move out of range of such a thing in three seconds even if we are the only ones on the field. Think about it. Any significant crowd might be 25 yards wide. I can just about do 12 yards in three seconds. What happens to those at the center when they have to wait for others to clear the field?

Radiation that can cause pain in 3 seconds will cook the skin in another few seconds. Read the fine print, people. It says that it causes pain by heating. Think how long it takes for sunburns to start hurting, and by that time you're usually in big trouble.

Any crowd of people is unable to clear an area quickly under the best of conditions. Police know very well that all they have to do to start a riot is to order a crowd to disperse, then start shoving them from behind to speed them along. Simple physics prevents those who are shoved from going anywhere. The police, being stupid, interpret that as deliberate non-cooperation, then start using weapons on innocent people. As long as the front is bottle-necked, just like at the Coconut Grove, people won't be able to get out when they could have got out the door if they had all exited in an orderly fashion.

When they use these pain-inducing beams, we are going to see burns on anyone who is unable to get out of the way in a few seconds. The smell of roast pork will fill the air. One can only hope that some of the riot cops get caught in the beam too.
 
Aye, thats why when they start trialling them in the UK, they'll possibly get stopped. At least until the next gvt overeacts to something.
 
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