One of the most difficult segment in electronic to study is the radio frequency signal - especially when there are no tools and equipment to examine the patterns, direction, frequency as well as the strength of signal. This can be made more difficult if the research area having poor RF signal - because sometimes you don't know if your circuit is working or not. Unless the signal is very strong then most circuit easily works it keeps propagating at a consistent level of frequency.
Other thing such as electromagnetic (EMF) interference from are also contribute to the failure of a circuit - which means strong interference could disrupt the signal which is already in poor condition. That's why the field of radio frequency require some level of expertise, experience, as well as the right equipment to succeed. We know there are plenty of cheap RF amplifier ready made in China - but to buy them is making life too easy leaving the gap of understanding stay as it is and some of them are not cheap especially good quality RF analyzer.
Despite of that we can build the experience steps by steps over the years - and hopefully gathering the right equipment so assist in further understand of the RF signal. For example the antenna that received or transmit RF signal is not as easy as you may think. Just by adding signal probably you will get a better signal or no improvement at all - the most important question is why is that? -- why sometimes the antenna does affect the RF signal and sometimes it doesn't at all - although the subject of test is the same at the same location and same antenna. In this scenario sometimes is the placement of the device - must be kept away from all sort of electromagnetic interference and also the direction where it is being place can affect great significant to the signal.
This experiment is done on HuaWei 4G modem which having different level of signal strength when it is placed on certain location. Although generally it is in one place (bedroom). But it does have effect if it is place near a PC or away from the PC since there is magnetic interference among all the electronic devices.
One of the basic equipment to have should be a frequency counter or multimeter that have the frequency measure capability. Other sophisticated equipment with the like of RF analyzer tools, Oscilloscope, and specialist RF analyzer software to monitor the performance of frequency and how
much power it is emitted or received.
This picture illustrate - a slight tiny bit of positioning the modem to obtain 4 bar signal of the 4G. As you can see the modem just a tiny twist slightly off the horizontal perfect line and there come the 4 bar 4G signal. The usual signal i get inside the room is around 1 bar, average 2 bar and maximum of 3 bar. Just by changing direction a little bit it obtain up to 4 bar which is quite good. It is not easy since the modem is placed within closed door blocked from all direction - but still able to obtain 4 bar.
The 4 bar signal is no coincidence - if there is tool to measure it could be that the modem is facing the right direction where the signal from the cell tower is to. But not all the place in the room will get the 4 bar signal and only in front of the PC and slightly off horizontal position.