The next day.
When Bai Yang finished his classes and returned home, he saw the mobile radio monitoring vehicle parked downstairs.
A white seven-seater van with a large disc mounted on its roof—to ordinary people, it was most commonly seen at college entrance exam venues. Without guessing, Bai Yang knew who had brought it here. He clicked his tongue in amazement—Uncle Wang was pulling out all the stops.
Back home, Wang Ning, Zhao Bowen, and his father were crowded in his room. Wang Ning wore headphones while adjusting the Icom 725, with Zhao Bowen and his father watching from both sides.
“What’s the SWR?”
“SWR is 1.3.”
“Then what’s the problem? I thought it was an impedance mismatch causing all the energy to be reflected.”
“Obviously not—I’m using an automatic antenna tuner. Look, the tuner indicator is green, so it’s fine.”
“Then why is the signal so weak on the spectrum analyzer? If it’s not an impedance matching issue, where’s all the transmitter’s energy going?”
“Dad! Uncle Wang! Uncle Zhao! I’m home!” Bai Yang stood at the doorway with his school bag. “How long have you all been at this?”
Wang Ning removed his headphones and got up, offering the chair to Bai Yang.
“About an hour and a half. We started at 8:30 PM,” Wang Ning checked the time on his phone. “We just contacted BG4MSR and greeted the young lady. She asked when you’d be home from school.”
Bai Yang moved sideways to put his schoolbag under the desk. He noticed screwdrivers on the table. “Did you take apart the radio?”
“Opened up the case to look inside,” his father said. “Your Uncle Wang always suspected I’d modified this radio, so I just let him take a look.”
“And?” Bai Yang asked.
All three men shrugged.
“We can now confirm it’s not an issue with the IC-725 itself.”
The four of them sat on the living room sofa, with Bai Yang eating his late-night snack from a plate.
The snack was fried noodles. Mom had gone to bed after making it, and Dad should have been asleep by now too, but they were currently holding an Amateur Radio Anomaly and Technical Symposium.
The distinguished attendees included:
Director Wang Ning, representative of the Nanjing Radio Administration Committee.
Associate Professor Zhao Bowen, representative of Nanjing University’s School of Physics.
Bai Zhen, representative of Nanjing’s ride-hailing drivers.
Bai Yang, a senior student representative from Nanjing Aeronautics University Affiliated High School.
The symposium was chaired by the ride-hailing driver representative and retired communications technician, Bai Zhen.
Wang Ning, representative of the Nanjing Radio Administration Committee and executive member of the National Political Education Department’s Universal Hairstyle Association, spoke first.
“We have a discovery,” Wang Ning said. “Tonight we measured the IC-725’s radiation field strength again with the spectrum analyzer and found something very strange.”
“What’s strange?” Bai Yang swallowed his noodles, licked the oil from his lips, and looked up to ask.
“The IC-725’s signal is weak. Remember, Yang? When we monitored the signal with the spectrum analyzer the other day, we couldn’t hear BG4MSR’s signal, and the IC-725’s signal was also very weak,” Wang Ning said. “At first, I thought it was a severe impedance mismatch between the radio and antenna, but the SWR meter showed everything was fine.”
“I know,” Bai Yang nodded. “The antenna tuner’s light was green, so of course it was fine.”
“So we tried several other bands,” Wang Ning continued. “Very peculiar—whether it’s six meters, two meters, or seventy centimeters, all other bands are normal. Whether measuring with the spectrum analyzer or SWR meter, twenty watts show as twenty watts. But only at 14 MHz—as soon as we enter 14 MHz, the IC-725’s transmitter signal strength drops dramatically. Conservatively estimated, the transmitted power is less than one-tenth of the radio’s power.”
“Where did the remaining nine-tenths of the energy go?”
Bai Yang froze, putting down his plate.
“That’s what we’re trying to figure out,” Zhao Bowen said. “Where did the remaining energy go?”
“Energy can’t just vanish—conservation of energy is a fundamental law, right?” Bai Yang asked. “If the energy isn’t being transmitted through the antenna, then it must be reflected.”
It was common knowledge that radio stations transmitted electromagnetic waves through antennas.
The electromagnetic waves generated by the transmitter are conducted through the feedline (coaxial cable) to the antenna, and then radiated to the outside world—this is the basic propagation process of radio signals. However, the electromagnetic waves generated by the transmitter can never be 100% radiated; no radio station is that efficient. Energy must be lost during transmission, with some waves being reflected along the path to the antenna rather than radiating smoothly—in simple terms, they’re blocked back.
The more waves that are blocked back, the lower the radio’s efficiency; the fewer waves blocked back, naturally the higher the efficiency.
If too much is reflected, if too many waves are blocked, then energy will accumulate inside the radio and convert to heat, burning out the transmitter.
This is something all HAMs pay attention to.
To avoid burning out their rigs, the HAM community has mastered the key factors determining whether electromagnetic waves can be efficiently transmitted: one called resistance, one called reactance, together called impedance.
When the feedline’s impedance matches the antenna’s impedance, electromagnetic waves generated by the transmitter can smoothly radiate out. When the urethra is clear, the bladder won’t explode—this is called impedance matching.
So how do you determine if the impedance matches?
The most common method is the SWR meter, measuring the standing wave ratio. The closer the SWR is to 1, the better the impedance match; otherwise, you’ll burn out the radio.
Some old-timers act like it’s doomsday if the SWR exceeds 1.1.
“That’s usually the case. Everyone knows energy conservation is a fundamental law, but it doesn’t apply to your IC-725. The waves aren’t being reflected—they’re mysteriously disappearing… Don’t believe it? Yang, you can try it yourself,” Wang Ning pointed at the door.
Bai Yang went into the room and turned on the radio, with Wang Ning following, carrying the spectrum analyzer. They began experimenting.
“Increase the power a bit,” Wang Ning reminded him. “Twenty watts.”
“Is it safe?”
“It’s fine.”
“The Radio Administration won’t give me trouble?”
“I am the Radio Administration.”
Bai Yang increased the IC-725’s transmitting power to twenty watts, first pressing the transmit key at 14.255 MHz.
A small peak rose on the spectrum analyzer’s oscilloscope.
“Good, now try any other frequency,” Wang Ning said.
Bai Yang casually turned the radio’s tuning knob. The numbers on the LCD jumped chaotically before settling at 50 MHz.
Pressing the transmit key again, the peak on the spectrum analyzer suddenly surged up like a balloon being rapidly inflated, the readings skyrocketing.
“The spectrum analyzer measures radiation field strength. Radiation intensity is related to power, not frequency. In theory, if you maintain twenty watts of transmitting power, whether at 14 MHz or 50 MHz, the radio’s transmitted signal strength should be consistent,” Wang Ning said. “But this IC-725 is very strange. As soon as it enters 14 MHz, the signal strength detected by the spectrum analyzer drops dramatically. The IC-725 is still running at twenty watts, but the signal strength received by the spectrum analyzer is less than two watts.”
“What does this mean?”
“It means not only is BG4MSR’s signal strange, but this radio is also strange,” Zhao Bowen stood behind them. “Once we enter the 14 MHz frequency, the IC-725’s radiated energy vanishes. We can’t detect it even with a three-way line connecting the spectrum analyzer to the antenna. Nothing works—increasing power to fifty or a hundred watts is useless. This suggests it’s not even reaching the antenna through the feedline. We can only conclude the energy is disappearing inside the radio itself.”
“Then where did the signal go?” Bai Yang asked. “Through space-time?”
“We can’t jump to such conclusions yet,” Zhao Bowen shook his head. “Our current experimental conditions are very limited, and our tests are quite rough. It would be best to test it in an anechoic chamber.”
“Where can we find an electromagnetic anechoic chamber?” Bai Zhen asked.
Zhao Bowen thought for a moment, “Nanjing Tech should have one. I’ll ask if we can borrow it.”
Though they said they couldn’t conclude without further experiments, Zhao Bowen, Bai Zhen, and Wang Ning knew in their hearts that changing experimental conditions would likely yield the same results.
None of the three adults believed the trans-temporal communication explanation, but neither could any of them explain the mysteriously disappearing signal.
“I admit this is beyond my understanding,” Wang Ning spoke up. “It’s not a radio issue.”
“Let’s put aside the anechoic chamber for now—we’ll deal with that when you can borrow it, Old Zhao,” Bai Zhen said. “The key issue isn’t here. The most important thing is to confirm whether BG4MSR will live twenty years in the future. This is the core question.”
“She does,” Bai Yang said. “I’ve verified it.”
“We know you’ve verified it,” Zhao Bowen said. “But a single piece of evidence isn’t enough. Experiments must be reproducible to be meaningful.”
Bai Yang paused. “So… you’re planning to do time capsules too?”
It had indeed developed to this point, Bai Yang thought. No one would believe such an absurd fact based on just a few words—to convince them, they needed to verify it themselves. Seeing is believing.
However, regarding the many issues with time-mail, Bai Yang had already stumbled through the pitfalls for them. They only needed to follow the stones across the river, replicating the successful path Bai Yang had blazed. Compared to Bai Yang’s initial blind attempts, Uncle Zhao, Uncle Wang, and Dad had it much easier.
“If you’re going to send time capsules,” Bai Yang said, “you must pay attention to several key issues, otherwise you’ll likely fail. This is a precious experience bought with my blood and tears, so make sure to remember it well… First point!”