One more concept to realize is that since antennas are passive devices, they have to be reciprocal. In other words, radiation that goes through a reciprocal system has to work the same way forwards and backwards. In simpler words, if you imagine transmitting through the antenna and looking at the radiation pattern from far away--that antenna behaves exactly the same when the radiation shows up from far away receiving into the antenna--it behaves the same in transmission and reception.

Each phased array antenna element can be thought of as a radiator, and if its an active array, the radiating element can be thought of having a tuneable amplitude and phase. And the combined radiation pattern of the array is a superposition of all the individual elements.

When you have that kind of control, you can change the far-field radiation pattern by adding delays and changing the amplitude to tune the radiation pattern. It's quite ingenious actually.

> how does any sort of flat plate collect incoming radio waves as well as or better than a semi-spherical (?) dish?

So the really counterintuitive fact here is that the amount of far field energy that an antenna can collect is a tradeoff between how directive it is and how much it can collect from a particular direction.

i.e. assuming your antenna is 100% efficient, and say antenna A collects energy from all directions, and say antenna B collects energy only from the "top" hemisphere, antenna B collects energy from that direction twice as much as antenna A. In more technical terms, the directivity integral is always constant.

What's also kind of wacky is that generally speaking the bigger the antenna is, the more directive the antenna is--e.g. an antenna that's big generally collects better from its "boresight". The first paragraph still applies, so a big antenna is poor at collecting energy off-boresight.

A phased array is a curious idea. Start with a passive phased array, where you have one antenna element, and you add the contributions from that one antenna element copy-pasted in space.

generally speaking the further an antenna element is spaced apart, the more directivity you get, since the physical size is larger. If you have many of these elements copied across a large surface, your directivity increases a lot.

A passive array is kind of dumb since you might as well just have a parabolic reflector antenna ("dish")--but an active array is where it shines.

You can tune the exact phase and amplitude contribution from each phased array element, and when you do that, you can tune the exact radiation pattern of the phased array. You can steer the "boresight" by delaying the input from some elements; you can make the antenna less directive or more directive; you can make it so that there are multiple boresights (useful if you want to track multiple radar targets); etc.

For pure efficiency and directivity, a parabolic reflector is best. That's why it's used in radio astronomy. Active phased arrays are used in military and high performance radios since you can change the radiation pattern pretty much instantaneously.

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In reality, geochemical studies suggest that radiogenic heat plays a small role in the energy balance of the core. Cooling and phase transition are the main processes.

The part where radioactive decay is the main heat source is the mantle.

The core is molten because it's hot and under high pressure. Essentially, the Earth was very hot and it's cooling down.

In fact, the size of the solid part, i.e. the Inner Core, continuously increases.

Yes, dromedary and Bactrian camels can cross-breed and produce fertile offspring, known as a "camel hybrid". However, it is not a common practice as the two species have different adaptations to their respective environments and it's not clear whether the hybrid would have the best characteristics of both the parents.

Gravity causes the pressure. It’s the weight of everything above pressing down, which naturally increases the deeper you go.

releasing pressure makes something get colder. increasing pressure makes it get hotter.

so where is the increase in pressure coming from that keeps the core hot?

what actually keeps the core hot is radioactive decay on unstable isotopes

The core's main heat source comes from radioactive decay of elements leftover from planetary formation, not from pressure.

Have you ever felt a spray bottle get colder as you release the pressurised gas/content?

In Earth's core it's the other way around. High pressure makes the core hot. The high pressure itself is from the mass of the kilometers of dirt and stone and water etc.

What forces keep the core molten as it is? (I think)

Also is the heat dissipating? If so I'm sure the heat lost is close to the heat generated by whichever forces because the Earth has been hot & "hot as a mf" on the inside for so long.

Lol sorry & thanks, wouldn't bother a whole post, but seemed like you may know or be able to point me to a good set of terms to search to understand this better.

Yes, they can interbreed. Bactrian camel have 2 humps and are rugged cold-climate camels while Dromedaries have one hump and are desert dwellers. Bactrian/Dromedary hybrids are called Bukhts, are larger than either parent, have a single hump and are good draft camels.

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Wouldn' friction with outer layers be a factor here?

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Have you heard of the silver fox experiment in Russia ? A man took wild foxes and within 10 generations changed them from wild animals to the equivalent of domesticated dogs. So with constant conditions, evolution can happen relatively quickly.

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This is such a great explanation for carcinogens. I was excited to answer this question but you've done a perfect job. Do you work in a biology related field by chance?

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