How was the sending of radio signals possible in 'Interstellar'?

Question

In the movie 'Interstellar':

When Cooper and his team was inside the wormhole near to the Miller's planet, they were getting signals from the earth but nothing was going out.

Now my questions are: (a) How were the signals from the earth sent to them? Because radio communication in deep space requires focusing (facilitated by dish and high gain antenna) to have a particular direction for the radio signals in order to not dilute them. When the signal will cross the wormhole it will be in a deep space in new world and it will not have any particular direction it will not have any particular direction or it will lost its direction and the signals will be extremely diluted before it reaches Endurance or may be possibly never reach.

(b) What may be the possible reasons of no signals getting out?

Answer 1

Based on the dialogue in the film (and in more detail in the novelisation), we can ascertain that there are two relay stations; one on each side of the wormhole. The one on the Gargantua side appears to be unable to transmit data back through the wormhole but it's still receiving info from the planets and from Earth. Since the two probes are acting as beacons, you don't need to wide-beam a message through the wormhole, you simply point it at the relay station:

All were star fields which looked as if they had been photographed through a fish-eye lens.
“From the relay probe?” Cooper asked.
“It was in orbit around the wormhole,” Doyle confirmed. “Each time it swung around, we got images of the other side of the foreign galaxy.”
“Like swinging a periscope around,” Cooper said.

later

“The lost communications came through,” Doyle informed them.
“How?” Brand asked.
“The relay on this side cached them,” he explained, as he continued to parse through it.
“Years of basic data,” he added. “No real surprises. Miller’s site has kept pinging thumbs up, as has Mann’s… but Edmunds went down three years ago.”

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There is no reliable information in either the film or novel to explain why relay station wasn't able to send more complex messages back through to Earth. Equipment failure seems the most likely reason since the "pings" are still being relayed successfully:

“No,” Doyle confirmed. “Data transmission back through the wormhole is rudimentary—simple binary ‘pings’ on an annual basis, to give some clue as to which worlds have potential.” He paused, then added, “One system shows promise.”