I posted yesterday asking how can I have signal inside my house which my house is obstructed by a hill from direct signal from the cellular's operator' Base Transceiver System (BTS). The schema of the system will be something like the first picture, but could be with additional electronic device in between the two antennas to make the system become active. But one commented and shared a link here which asked the similar question which from my understanding, the schema should be like first picture.

I also searched in Youtube if any can help and solve my problem. Then I got these two videos (video 1: 850mhz cell phone signal booster Yagi antenna and video 2: Homemade portable 1800mhz 4g LTE signal booster). The schema are something like the second picture. From the two videos, the folded cable at another end are acting like antenna to the attached mobile phone.

From the schema 1, one commented quite comprehensive. If I didn't understand it wrongly, he recognized that the system is working but with some limitations and he recommended that rather than to make himself, better to buy with only $100. Then my question for both the schematic:

  • Are they really work?
  • If they are really work, how they work without any active device?

The second schema (the two videos) I tried and both are didn't work. But my failure could be due to wrong design/installation. That's why I ask here. And I appreciate any helping comment.

Antenna System1, Rx/Tx-Tx/Rx omni First picture

Antenna System2, Rx/Tx-Tx/Rx induction Second picture

  • 1
    $\begingroup$ transmission line theory. They work because of transmission line theory, and since this is the sixth question you ask that you could answer by that, I don't think it makes much sense for us to answer in depth. Get a transmission line theory / EM basics book. Your questions are all too broad, because you try to skip the basics. $\endgroup$ – Marcus Müller Aug 9 '19 at 18:27
  • $\begingroup$ Did you really watch the two videos I mentioned above? I worry that you miss understood my point. But if you don't want to answer, no problem. It is absolutely your right. No force you even to comment here. $\endgroup$ – Sitorus Aug 10 '19 at 1:11
  • $\begingroup$ Mobile phone antennas are very bad and receive signals from most directions (they have low gain of e.g. 0 dBi). There are high gain antennas (e.g. G = 16 dBi) that you can and must aim at the base station. A short coax could have e.g. 2 dB loss and additional 3 dB is lost when the plate of video2 couples with the phone. This means that, because of the high gain antenna outside, the phone receives 16 dBi - 2 dB - 3 dB = 11 dB more signal than with its (0 dBi) bad antenna. Try to understand these concepts and then ask more specific questions.Building one is difficult, take one step at a time. $\endgroup$ – OH2FXN Aug 28 '19 at 16:46
  • $\begingroup$ @OH2FXN, thank you my friend for your explanation. Regardless of the loss of the coax cable, my concern here is more about is that such "system" works? Mean, will a signal received by an antenna passed and transmitted to another antenna without any active component? As I have tried, no one is working. Apologize if I bothered you with this question. $\endgroup$ – Sitorus Aug 30 '19 at 23:55
  • $\begingroup$ @Sitorus: I have never built our seen one, but I don't see any reason why such a system couldn't work. However, I see many possible reasons why building one could fail. If you don't have proper measurement equipment available, it's very difficult to debug the system. $\endgroup$ – OH2FXN Aug 31 '19 at 5:50

We used to use a similar set up for 2G GSM/DCS and pagers many years ago, where rx levels were marginal and we wanted to 'reach around corners'. We called them 'passive repeaters'. Results were mixed to say the least but we did have some successes.

  • $\begingroup$ Are they really work? Forget about the antenna design, I will take care it. What I need just to make sure that the system is work without any additional active device in between the two antennas. If you don't mind, which one will work? I do frustrated as my antenna is not working with schematic like the second picture.. $\endgroup$ – Sitorus Aug 10 '19 at 12:39

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