Search found 85 matches

by snn47
Mon Apr 16, 2018 6:36 am
Forum: Antennas
Topic: UltraWideBand antenna design
Replies: 18
Views: 2110

Re: UltraWideBand antenna design

Frequencies will vary with region and if you have weather, civil or military Radar Towers in view. Except the L-Band Radars ~1215 - 1400 MHz, most other Radars are above 2700 MHz.
by snn47
Mon Apr 09, 2018 3:07 pm
Forum: Antennas
Topic: Any cheap L-band feedhorn?
Replies: 14
Views: 1288

do you need broadband and/or high gain?

By definition L-Band is 1 to 2 GHz, so the answer depends on which signals you want to receive, how wide is the segment you want to receive and how strong the signals that you want to receive that will answer your question. You only asked about the antenna, but keep in mind that the - antenna gain i...
by snn47
Fri Apr 06, 2018 7:01 pm
Forum: Antennas
Topic: what frequencies can this pick up?
Replies: 6
Views: 571

Re: what frequencies can this pick up?

what signal could i potentially get Potentially every signal strong enough to be received at your location, that can be processed by a SDR dongle due it's limitation in frequency, bandwidth and amplitude, and for which there is software to decode the signal, like e.g. AM, FM, CW, USB, LSB, ADSB. Pl...
by snn47
Wed Apr 04, 2018 3:20 pm
Forum: RTL-SDR Discussion
Topic: Will the RTL-SDR work for digital frequencies?
Replies: 6
Views: 781

Re: Will the RTL-SDR work for digital frequencies?

There are no digital or analogue Frequencies. Frequencies are often calle "analogue or digital" frequencies, because they are used for transmission of either analogue or digital modulations. A SDR can receive any modulations that is within the tuning/frequency range that they can tune to. The SDR ba...
by snn47
Sun Apr 01, 2018 3:45 am
Forum: RTL-SDR Discussion
Topic: Cable for LNA question
Replies: 3
Views: 341

Re: Cable for LNA question

It depends, - is your coax ok, - has never been mistreated, like bend below the allowable radius, otherwise replace it - are your coax connector still mounted correctly and are not corroded, otherwise cut of the damaged coax section, and/or replace connectors and/or cable as needed, because the cabl...
by snn47
Fri Mar 30, 2018 10:04 pm
Forum: Antennas
Topic: what frequencies can this pick up?
Replies: 6
Views: 571

Re: what frequencies can this pick up?

can it be used for tv?, dab?, analogue radio?, other things? Which frequency ranges did you have in mind, which polarization have the signals you are interested in? Everyone will need a glas ball to anwer your Question, without some information. Another problem is knowing what antenna design the Fl...
by snn47
Thu Mar 29, 2018 6:59 pm
Forum: Antennas
Topic: NOAA APT 137MHz DIY antenna only with 75Ohm coax
Replies: 8
Views: 602

Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

OK thanks. I am asking because i saw 75 Ohm and 50 Ohm cables combined for some antenna (Turnstile, Cross Dipole etc.) The 70 Ohm cable is normally used only for phasing purposes when combining the two dipoles, while the feeding cable is 50 Ohm. Check HAM Radio literature, e.g. ARRL antenna handboo...
by snn47
Wed Mar 28, 2018 4:59 am
Forum: Antennas
Topic: Where do the antenna actually begin?
Replies: 8
Views: 1241

antenna begins at the feedpoint = point B directly at the coax

The antenna begins at the feedpoint = point B directly at the coax in your case. The length of the connector's 'shield' is insignificant and has no impact on the wire's resonance if it has the length of 1/4 and is either mounted on a metal shield as ground plane/counterpoise or you can use 3 or more...
by snn47
Tue Mar 27, 2018 2:19 am
Forum: Antennas
Topic: Three 1-meter antennas = One 3-meter antenna?
Replies: 2
Views: 426

Re: Three 1-meter antennas = One 3-meter antenna?

In theory it works, but you in order to achieve the same gain you have to align all dishes. Alignement is imho the main obstacle to achieving the desired gain.
by snn47
Tue Mar 27, 2018 2:16 am
Forum: Antennas
Topic: Any cheap L-band feedhorn?
Replies: 14
Views: 1288

Re: Any cheap L-band feedhorn?

Just combining a feed (horn) and a dish won't make an efficient antenna. Just throwing a dish and a random feedhorn together is unlikely to allow you to come even close to the theoretical gain that a certain dish size could provide, because a feed horn design has to matches the F/D of the dish (http...