View Full Version : Contacting and using satelites
01-13-2010, 03:45 AM
I`m new to ham basically and have never read an article about using satelites for making contacts.
I`m curious, you pretty much have to use a beam, right? How do you control your beam to follow the track of the satelite? Meaning across the sky and the elevation degree that the beam needs to be at?
AMSAT-NA web site is a good starting point for amateur radio satellites.
IF you use a beam antenna (e.g. Arrow II Satellite Antenna or clone) --
see the video by K7AGE or use the Arm Strong method (manual tracking)
Current status of all amateur radio satellites (Oscars)
Hope Oscar 68 (XW-1) launched by the Chinese on December 15, 2009 is the newest satellite.
It has a 200 mW (23 dbm) beacon on 435.7900 MHz -- CW that you should be able to hear
with a multi-mode 70 cm receiver.
Check published schedule (each week by AMSAT-CN) to see if it is in SSB/CW transponder mode OR
FM repeater mode. The satellite transponders are commanded OFF ---
when the satellite is in prolonged eclipse to maintain batteries -- BUT the beacon normally stays ON.
You will also need satellite predication / tracking software to know where and when to point -- since these are Low Earth Orbiting (LEO) satellites -- with only a maximum of 11 to 12 minutes for each visible pass !
LEO satellites usually stay below the Van Allen Radiation belts, named for Iowa native James Van Allen (sk).
IF you have time, contact Ken, KA0Y or K3JNZ !
Ken was been a long-time EME and VHF/UHF contest operator.
He built his own 50 foot dish in Riverside, IA in late 1970s. I first saw it when in graduate school at Iowa in early 1980s. He was also one of the first US stations to work Owen Garriott on STS-9 (Spacelab-1 mission) --
the first usage of amateur radio on manned USA spacecraft.
He moved that big dish and its WW2 destroyer gun mount twice over the past 30 years. He recently sold that station and property to William Hartley, K3JNZ.
01-13-2010, 04:19 AM
I`m new to ham basically and have never read an article about using satellites for making contacts.
I`m curious, you pretty much have to use a beam, right? How do you control your beam to follow the track of the satellite? Meaning across the sky and the elevation degree that the beam needs to be at?
Yes you typically need two yagi antenna's. One is configured for the down link frequency and the second yagi is configured for the uplink frequency.
I control the yagi using az-el rotor system. You can also use a TV rotor and then construct an elevation device a number of ways including the idea of installing a old satellite tv dish actuator arm from the older larger sat tv dishes from the 80's to control the elevation of the antenna.
Precision is tracking is not critical nor does it have to be elaborate. Sometimes you can simply track the signal by monitoring the signal reading in the receiver.
You can find out when a satellite "footprint" for a given satellite is hovering above your home in your area by using a free program called Orbitron.
Hope that helps.
01-13-2010, 06:43 PM
For the current batch of LEO satellites, yagis and elaborate tracking systems are nice, but major overkill. Simple omni antennas will work fine for starters.
The favored antennas would include turnstiles, eggbeaters, and quadifilar helix antennas. The eggbeaters and quad helix antennas could do double duty for working the local repeaters and SSB stations too, as they have both vertical and horizontal polarization.
You can build all of these fairly easily. The turnstile is just two dipoles fed though a coax matching harness. 75 ohm coax works for the harness, but 92 ohm is better.
There are at least two handheld beams for sale for use with satellites. Arrow makes the best known one. This is intended to be held in your hand and pointed at the satellite. However, you can sometimes make contacts with just an aftermarket whip antenna on your HT.
YouTube has some excellent videos on using ham satellites. http://www.youtube.com/watch?v=1HfvmU_utI8
Search on 'ham satellites' for many more examples.
01-13-2010, 09:23 PM
Thanks guys for the good info.
I`ve been interested lately on how antennas work. I`m only at the beginning stage so far but I would some day like to build afew from scratch.
I bought ARRL`s Yagi Antenna Classics and it is a good read but seems to have more antennas to build. Thought at the time I was buying (from Amazon) a book more about the fundamentals of antennas theories and what goes into making them. But I see a couple antennas in the book I have that I may try out sometime.
I plan on picking up the book Basic Antennas: Understanding Practical Antennas and Design by Joel Hallas. This book may be more my speed at this point. Not understanding some of these equations about antennas just yet. Even went thru my General Class Licence book for a bit of a refresher.
01-13-2010, 11:47 PM
Here's a commercial UHF quad helix I just found - looks like a nice package.
You'd need one for 2 meters, too, obviously. They mention a companion 2 meter unit, but no mention of it it became reality or not.
Here's an easy eggbeater design for both bands: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=22289
This is a pretty elaborate turnstile: http://www.mikestechblog.com/joomla/ham-radio/ham-radio-antennas-category/65-2-meter-turnstile-antenna-for-amateur-satellite-communications.html
If you're an ARRL member, Cebik published a really nice homebrew design in August 2001 QST. If you search their website for 'turnstile' you'll find it.
My friend and I were heavily into LEO satellites years ago, and we built the world's most hideous turnstile antennas, and it usually started an hour before the next satellite pass. We used a lot of pieces of wood, coat hanger wire, and glue. And we always made contacts on the birds.
I have been interested lately on how antennas work. I`m only at the beginning stage so far but I would some day like to build a few from scratch.
IF you are an ARRL member, then the January and February 2010 issues of QST has a DIY Build Technical article by Anthony Monteiro, AA2TX for building Lindenblad VHF and UHF omni-directional antennas suitable for amateur satellite usage!!
Here is the 2006 AMSAT Symposium version - 70 cm (UHF) antenna
AC4LT version of Lindenblad antenna on Flickr !