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Step to the neutron stars 11. RF bandpass filter

In the case of artificial radio interference (Radio Frequency Interference), the external filter is a necessary part of the radiotelescope. Let's start with the basics. In the simplified case, the bandpass filter has two parameters: main frequency and bandwidth. The bandwidth is measured at -3dB, ie when the signal is twice weaker. The frequency in […]

Step to the neutron stars 9. How RTL-SDR works

The best article I have seen on the principles of the RTL-SDR receiver operation is described here. Here is a brief synopsis of this article. In a few simple steps, I will try to tell you how this receiver works. Step 1. Simple demodulation Let us assume that we have a signal with amplitude modulation […]

Step to the neutron stars 8. Assembly and test of antenna

The construction of the antenna took time. But it ready and it wiggly fit in my apartment. The construction of the antenna I start with linking of the boom sections. I will remind the reader that I make the boom of three parts. Each part is a 1m long square tube (10x20x1000). For their connection, […]

Step to the neutron stars 7. Some practical questions

Here I summarize some questions, which I had asked myself and on which I had found the answers. Why the impedance of the antenna is 50 Ohm when the open dipole has 73 Ohm? An antenna that has multiple elements also has an impedance that is different from the impedance of the dipole. The same […]

Step to the neutron stars 6. Antenna theory in practice

In this note, I will progressively explain some basics of antenna theory and will present the results of antenna modeling. I had already used a few terms (directivity, impedance), which I had not introduced yet. So I think it is a good time for this. Lets will be normalized on peak value radiation pattern. The […]

Step to the neutron stars 5. Antenna simulation

As any creative project have the turns in the wrong way, the same happens to me when I had considered an in-phase antenna array. The problem of this antenna is not only in matching but also in high mechanical complexity. The mechanical structure should be made from dielectric material. If I would be in my […]

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