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GPS has three seperate frequency bands which are L1, L2 and L5 while Glonass has two seperate frequency bands including L1 and L2. Also Galileo has three frequency bands named as E1, E6 and E5.

I want to select an antenna that can receive all the frequencies mentioned above to connect my HackRF One module to process these signals. So, first property of the antenna that I should be aware of would be its bandwidth.

HackRF One can easily acquire the signals if a suitable antenna is selected to its input port. Input port of the HackRF One is 50 ohm, so impedance of the antenna should be referenced to 50 ohm. Therefore, the second property of the antenna is its VSWR value.

Apart from two properties mentioned above, there is one thing that should be accounted which is antenna's gain. I am quite confused about this one. What should be suitable value of the antenna's gain to acquire GNSS signals?

I think one of the most suitable choice would be a telescopic antenna since the market offers lots of telescopic antennas.

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I think one of the most suitable choice would be a telescopic antenna since the market offers lots of telescopic antennas.

I don't think it works like that. There's a lot of cheap sand on the market. If you want to bake a cake, flour and sugar would still be a better choice...

Also, telescope antennas are extendable, and monopoles, and thus not multi-band matched to 50Ω!

HackRF One can easily acquire the signals if a suitable antenna is selected to its input port.

Nope. When you look at how GPS receivers work, you'll see that for noise figure reasons, there's a low-noise amplifier very close, normally even integrated with the antenna. This is necessary because the power density of GNSS signals when they reach your antenna is so very low that they'll just disappear into receiver noise in your HackRF.

So, you need an active antenna. And to supply that with power, you need a bias-T, too.

So, buy a commercially available GPS/GNSS patch antenna and a bias tee.

one thing that should be accounted which is antenna's gain

nah, not really unless you know how the antenna is going to stay in a fixed orientation. If it does, 3 dB is the gain you want - that's the gain you get when you don't observe the half of space where the earth is. You need to get multiple satellites for any GNSS to work, so the observed part of the sky mustn't be too narrow.

Again, commercially available GPS antennas.

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  • \$\begingroup\$ Thank you Marcus, shouldn't have engineers who designed the HackRF One put an LNA inside the module? Why would I need an extra LNA? As far as I know, HackRF team suggests a telescopic antenna named as ANT500. (Link: greatscottgadgets.com/ant500 ) But as can you see, the bandwidth of the antenna doesn't meet my requirements, therefore I am searching a telescopic antenna having higher bandwidth values. \$\endgroup\$ Nov 16, 2020 at 8:41
  • \$\begingroup\$ Mike did include an LNA in the HackRF when he designed it, indeed, but it's just not sufficient. For extremely low-power signals like GNSS, you want your LNA to be as close as possible to the antenna! That's the reason why practically all commercial GPS antennas are active. \$\endgroup\$ Nov 16, 2020 at 9:02
  • \$\begingroup\$ They don't "recommend" it for GNSS. They offer it as kind of a general purpose (not great for anything, but can be made to work somewhat at a range of frequencies by extending it appropriately) antenna. It's not suitable at all for your use case. \$\endgroup\$ Nov 16, 2020 at 9:04
  • \$\begingroup\$ Since an LNA is not a reciprocal network, can I transmit and receive signals by using one active antenna. Rather than asking about simultaneous TX and RX, I ask, can an active antenna achieve both TX and RX? One more question: What should be the gain, NF value of the LNA? \$\endgroup\$ Nov 16, 2020 at 9:27
  • \$\begingroup\$ no, you can't TX on such an antenna. For TX, you don't need an amplifier close to the antenna, and your potential receivers are extremely sensitive, anyway, so just leaving your TX port unconnected would work, too. You really shouldn't transit on GPS frequencies, though, it's highly illegal and might have safety-relevant implications – and criminal law ones, too. \$\endgroup\$ Nov 16, 2020 at 10:00

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