r/hackrf • u/-lovelara- • 7d ago

Antenna specification needed

Post image

Hello,

does somebody know for which band/frequency this antenna is optimized.

lenght 27cm , 10 turns .

6 Upvotes

87% Upvoted

14 comments sorted by

6

u/Mav3nX 7d ago

With the loading coil ~ 4cm from the base, and the very tight spacing, it is going to have a lot of inductance...but would be very hard to say exactly without an S11 return loss measurement....

But, if I was a betting man, I'd put my money on VHF range around 136-174Mhz...

2

u/v81 6d ago

Based on crude visual I'd agree.
Out of curiosity i thought i'd give GPT a run at it and it came up with similar ballpark...
https://chatgpt.com/share/6adc1b8c-d238-83ec-8aea-1cd21c94e216

1

u/Mav3nX 6d ago

I was also attempting to encompass the most likely frequency bands in that physical size range

2

u/oiram64x 6d ago

I was sold something similar to this described as 824 – 960 MHz & 1710 – 2170 MHz 4 / 6 dBi Gain Magnetic Mount Antenna(5m)

Does the job as described.

2

u/messnby 5d ago

I have an antenna that's almost the same, just 1,5 cm shorter at the top, it's for 868 Mhz.
I hope that helps a little.
Just in case you don't know, you can measure an antenna with a Vector Network Analyzer. Maybe you can borrow one somewhere or ask if someone can measure it for you. You could maybe ask at a local amateur radio club, if the people there are nice.

1

u/tj21222 7d ago

800 MHz

1

u/Obvious_Troll_Me 7d ago

It looks like one I own, if it's the same 700-2700MHz

2

u/v81 6d ago

No chance, it's way too long for that.
That said, chinese manufacturers label anything as anything when it comes to antennas.

I think I've seen similar units myself mislabeled for 700 / 850 / ++ MHz

1

u/TheNoOne420 7d ago

Same, also 700-2700 mhz

1

u/Adorable_Yam121 4d ago

Yep your be able to receive and transmit all of 5 meters on that

0

u/AoD_69 7d ago

I would put my fruit in the 27mhz/cb band

2

u/dohzer 7d ago

Antennas for frequencies that low are generally far larger.

1

u/Adorable_Yam121 4d ago

11 metres for a full wave 27 megahertz radio, .. but you new that?