Once We Lived in Nanjing

The next day.

When Bai Yang finished his day's lessons and returned home, he saw the mobile radio monitoring van parked downstairs.

The white seven-seater van, topped with a large dish, was commonly seen at college entrance examination sites to ordinary people, and Bai Yang knew without guessing whose van it was. He couldn't help but click his tongue; Uncle Wang was really pulling out all the stops.

Upon arriving home, Wang Ning, Zhao Bowen, and his dad were all crammed into his room, with Wang Ning wearing headphones and adjusting the Icom725, while Zhao Bowen and his dad stood by and watched.

"What's the SWR?"

"SWR is 1.3."

"Well, that's not a problem. I thought it was an impedance mismatch and all the energy was being reflected back."

"Nonsense, I'm using an automatic antenna tuner. Look, the tuner's indicator light is green, so there's no problem."

"Then why is the signal monitored by the spectrum analyzer so weak? If it's not an impedance matching issue, where did all the transmitter's energy go?"

"Dad—! Uncle Wang! Uncle Zhao! I'm back!" Bai Yang, holding his schoolbag, stood at the door, "How long have you guys been tinkering here?"

Wang Ning took off his headphones, stood up, and offered his chair to Bai Yang.

"About an hour and a half, we started at 8:30 pm." Wang Ning took out his cellphone to check the time, "We just made contact with BG4MSR, greeted the young lady. She was asking when you'd finish school and come home."

Sidling up, Bai Yang put his schoolbag under the desk, and saw a screwdriver laid on the table, "Did you guys open up the radio?"

"We opened the casing to look inside." His dad said, "Your Uncle Wang always suspects that I've modded the radio, so I just let him have a look."

"And?"

All three spread their hands.

"We can now confirm that it's not an issue with the BG2WW itself."

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The four sat on the living room sofa, with Bai Yang holding a plate and eating a late-night snack.

The snack was stir-fried noodles; his mom had already gone to sleep after making it, and at this time his dad should have been asleep too, but at the moment, a meeting was being held at home about the curious phenomenon and technical discussion regarding amateur radio.

The meeting's attendees included:

Director Wang Ning, representing Nanjing City's Radio Regulatory Commission.

Associate Professor Zhao Bowen from the School of Physics at Nanjing University.

Representative Bai Zhen, a rideshare driver from Nanjing City.

Representative Bai Yang, a senior high school student from Nanjing South Airline Affiliated High School.

The meeting was chaired by Bai Zhen, the rideshare driver representative from Nanjing City, and also a retired communications technician.

Director Wang Ning, representing the Radio Regulatory Commission of Nanjing City, who is also a member of the national political education department's Universal Hairstyle Association's presidium, was the first to speak.

"We have a new discovery." Wang Ning said, "Tonight we used the spectrum analyzer to measure the radiation strength of BG2WW again and found a very peculiar phenomenon."

"What phenomenon?" Bai Yang swallowed his noodles, licked the oil from his lips, and looked up to ask.

"Remember how weak the BG2WW signal was? The other day when we monitored the signal with the spectrum analyzer, we couldn't hear the signal from BG4MSR, and the BG2WW's signal was also very weak." Wang Ning said, "At first, I thought there was a severe mismatch between the radio and antenna impedances, but the SWR meter showed no problem."

"I know." Bai Yang nodded, "The antenna tuner has been green all the time, of course there's no problem."

"So we tried several other bands." Wang Ning continued, "Very peculiar, whether it was the 6-meter, the 2-meter, or the 70-centimeter bands, all other bands were normal. No matter if we used the spectrum analyzer or the SWR meter to measure, 20 watts was indeed 20 watts. Only at 14 megahertz, as soon as it enters the 14 megahertz band, the signal strength of the BG2WW transmitter significantly attenuates, and conservatively estimating, the emitted power is less than one tenth of the radio's power."

"Where did the remaining nine tenths of the energy go?"

Bai Yang was startled and put down his plate.

"That's what we're pondering too." Zhao Bowen said, "Where has the remaining energy gone?"

"Energy can't disappear into nothing; energy conservation is a basic law, right?" Bai Yang asked, "If the energy wasn't transmitted through the antenna, then it must have been reflected back."

Radio stations transmit electromagnetic waves through antennas; this is common knowledge.

The electromagnetic waves generated by the transmitter are conducted to the antenna via the feeder line (coaxial cable) and then radiated into the outside world by the antenna; this is the basic propagation process for wireless radio signals—However, it's impossible for all the electromagnetic waves produced by the transmitter to radiate out; there is no such highly efficient radio station in the world. There will inevitably be energy loss during transmission; some of the radio waves will be reflected back on their way to the antenna and cannot be smoothly radiated out, which is essentially being "blocked" and reflected back.

The more the radio waves are blocked and reflected back, the lower the efficiency of the radio station; conversely, the fewer that are blocked, the higher the efficiency naturally will be.

If too many are reflected back and blocked, that energy will accumulate inside the radio station and turn into heat, potentially burning out the transmitter.

This is an issue all HAMs pay attention to.

To avoid burning out the transmitter, HAMs have mastered key factors that determine whether electromagnetic waves can be transmitted efficiently or not – one is resistance, and the other is reactance; combined, they are known as impedance.

If the impedance of the feeder line matches the impedance of the antenna, the electromagnetic waves generated by the transmitter can be efficiently emitted. If the urethra is clear, the bladder won't explode; this is called impedance matching.

So how do you determine if the impedance is matched?

The most commonly used method is the standing wave meter. The standing wave ratio (SWR) is measured using the standing wave meter; the closer the SWR is to 1, the better the impedance match, and vice versa means risking burning out the transmitter.

Some old frogs would freak out as if it were the end of the world if the SWR exceeds 1.1.

"Usually this makes sense, everyone knows that energy conservation is a fundamental law, but it doesn't work with your rigged setup; the radio waves are not being reflected back, they are disappearing inexplicably... if you don't believe it, try it yourself, young Yang," Wang Ning said, pointing at the room door.

Bai Yang entered the room and turned on the radio station, Wang Ning followed with a spectrum analyzer, and they started to experiment.

"Increase the power a bit," Wang Ning reminded, "Twenty watts."

"It's okay?"

"It's okay," Wang Ning said.

"The Radio Administration won't bother me?"

"I am the Radio Administration."

Bai Yang increased the transmit power of the 725 to twenty watts and then pressed the transmit key at 14.255 megahertz.

A small peak arose on the oscilloscope of the spectrum analyzer.

"Okay, now just pick any frequency," Wang Ning said.

Bai Yang randomly twisted the tuning knob on the radio, and the numbers on the liquid crystal display jumped erratically before settling on 50 megahertz.

Pressing the transmit key again, the peak on the spectrum analyzer abruptly rose, like a balloon suddenly inflated, with the reading surging.

"Spectrum analyzers measure radiation field strength, the intensity of which is related to power and unrelated to frequency. Logically, if you maintain a twenty-watt transmit power, whether it's 14 or 50 megahertz, the signal strength emitted by the radio should be the same," Wang Ning said. "But this rigged radio behaves strangely; as soon as it enters 14 megahertz, the signal strength monitored by the spectrum analyzer drops sharply. Even though the radio is still operating at twenty watts, the signal strength received by the spectrum analyzer is less than two watts."

"What does this mean?"

"This means that not only is the BG4MSR signal odd, but this radio station is also strange," Zhao Bowen said from behind them. "As soon as it enters the frequency of 14 megahertz, the energy radiated by the rigged radio vanishes. Even if we connect the spectrum analyzer to the antenna using a three-way cable, we can't monitor it; no method works, not even increasing the power to fifty or a hundred watts. This suggests that the energy didn't even pass through the feeder to the antenna, and we can only assume the energy disappeared inside the radio station itself."

"Then where did the signal go?" Bai Yang asked. "Did it travel through time and space?"

"We can't jump to such conclusions for now," Zhao Bowen shook his head. "Our current experimental conditions are very limited, and the tests we've conducted are still quite rough; we'd better find an electromagnetic wave anechoic chamber for testing."

"Where can we find an electromagnetic wave anechoic chamber?" Bai Zhen asked.

Zhao Bowen thought for a moment, "South University of Technology should have one; I'll ask if we can borrow it."

Although that's what he said, without further experimentation, we can't jump to rash conclusions; Zhao Bowen, Bai Zhen, and Wang Ning themselves knew very well that the results would probably be the same even with different experimental conditions.

None of the three adults present believed in the explanation of super space-time communication, but no one could explain the mysteriously disappearing signal.

"I admit this is beyond my understanding," Wang Ning said. "It's not an issue with the radio."

"Forget about the electromagnetic wave anechoic chamber for now; Old Zhao, you can talk about borrowing it whenever you can," Bai Zhen said. "The key issue isn't there; the most important thing is to clarify whether BG4MSR really lives twenty years in the future, which is the core issue."

"It's real," Bai Yang said. "I've verified it."

"We know you've verified it," Zhao Bowen said. "But a single piece of evidence is not enough, and an experiment needs to be repeatable to be meaningful."

Bai Yang was stunned, "So what you mean is... you're also planning to send a time capsule?"

Sure enough, it had come to this, Bai Yang thought. Nobody could believe an absurd fact based on a few words alone, so to convince them, they had to verify it themselves, seeing is believing.

However, regarding the many issues with Time Slow Delivery, Bai Yang had already stepped into pitfalls for them; they just needed to feel the stones when crossing the river and follow the successful path forged by Bai Yang. Compared to Bai Yang's initial trials with utter cluelessness, Uncle Zhao, Uncle Wang, and his father had it much easier.

"If you're also planning to send a time capsule," Bai Yang said, "You must pay attention to several key issues, otherwise, there's a high probability of failure; this is precious experience I've gained through blood and tears, make sure you remember it well... The first point!"