Noob Q on Antennas

antennas

#1

I’m a total noob, wanting to do Satnogs for my high school science club on the Satnogs Network. We are located in Hawaii.

I have some questions:

I was looking at the omnidirectional and rotator build plans. The omnidirectional (non-rotator) uses a single antenna of various types, as mentioned here. The rotator build seems to use two antennas, as seen here.

I thought our team should start with the easier omnidirectional build with a single antenna, but I was thinking that as we progressed, we could move up to the rotator.

Can an omnidirectional also use dual-antennas, or does an omni need a single type of antenna?

Can an omnidirectional pick up signals from both LEO and GEO (such as NOAA satellites)?

Can an omnidirectional operate indoors, given the length of radio waves, or is a roof ideal?

Oh, one more thing, I know it’s not hardware, but it seems to me Linux is preferred to Raspberry Pi. True?

Please answer in the simplest words possible. Mahalo!


#2

I’ve just got my station running using a simple horizontal V dipole antenna made from thick wire left over from training fruit trees and it works surprisingly well.

Also, yes Raspberry Pis mainly use Linux. The SatNOGS image is based on the standard Raspbian distro from the Raspberry Pi foundation.


#3

The antenna can be installed indoors as well and still have good reception characteristics. My Wimo TA-1 (VHF) is under the roof, there are no metal parts interfering the reception. This way, no permission from the rest of the people living in the building was needed for the installation. That meant, no problem with insurance against lightning (for example). Also, some other hardware like low noise amplifier and FM filter, are protected from weather.

Omnidirectional antennas still have a preferred frequency range to receive the data. To receive the low resolution NOAA images, you need a VHF antenna, better when tuned for 137 MHz.


#4

Hope this helps. This isn’t law, just my experience.

Can an omnidirectional also use dual-antennas, or does an omni need a single type of antenna?
Yes. It will require a thing (called a duplexer) that splits the signal into VHF and UHF (for example) with filters. Two antenna cables come together and are joined so only one cable goes to the receiver. The other option would be to use two receivers but this is more complex and needs software changes (I would imagine) as the client is looking for a single receiver

Can an omnidirectional pick up signals from both LEO and GEO (such as NOAA satellites)?
What you are trying to observe will depend on what is in the database. The vast majority of stations are either VHF or UHF which cover what you mention. Omni’s will have reduced performance over tracking antennas but are way more simple to put together. A good clear view of the sky will give great results with an Omni.

Can an omnidirectional operate indoors, given the length of radio waves, or is a roof ideal?
Mine do, performance is reduced and sometimes can be poor but I have both a VHF and UHF Omni setup that work fine. Moving the antennas outside would improve the results but I live by a windy sea that eats Aluminium (similar to aluminum :wink: ). I don’t run anything like LNA’s as they caused too many problems for me. Equally I don’t need filters as the location is rural.

Oh, one more thing, I know it’s not hardware, but it seems to me Linux is preferred to Raspberry Pi. True?
The Raspberry Pi uses Linux. Using the SatNOGS image is very straightforward. No graphical bells and whistles but works well and doesn’t fall over

If you need help with hardware choice then just ask. There looks like a load of choices to be made for your GS but my advice would be start with the minimum (RPi, RTL-SDR and an antenna like a turnstile) and then build on that.

Alex


#5

Just to add that another option is to setup two different station, unfortunately this will require 2 SDRs and Raspberry Pis, one for each antenna.

+1 on starting with a simple setup and then build on that.


#6

@xlevel @pleira and others (new users can only tag 2).
Thanks for your replies and your input. I think it’s enough to get us started. We’ll either get a Raspberry Pi or a Windows PC box running Linux.

Oh, one more question on hardware: Is there a recommended tuner for use with the antenna?

Mahalo!


#7

Generally SatNOGS is receive only, so there is no tuner needed.
Pick your antenna to match the sats you want to receive and attach it to your SDR.
Just get started and learn as you go. (Is my humble advice).


#8

@Frederick i’d go Raspberry Pi 3+, and get the SDR & LNA from rtl-sdr.com.
Worked for me.