Amateur Radio Satellites

Allen Mattis N5AFV, Houston, TX


I made my first satellite contact on 16-July-2000, after seeing a satellite demonstration at Field Day a few weeks earlier. The equipment used at the Field Day demonstration consisted of an Icom W32A HT with an AL800 telescoping antenna. I own an Icom W32A HT, and I immediately realized that I could use it to make satellite contacts. I soon became hooked on operating satellites, and amateur radio satellite operation has become my primary hobby. 

One of my favorite amateur radio activities is to operate on the OSCAR satellites whenever I travel. I have operated on amateur radio satellites from 170 different Maidenhead grid squares, from 22 different DXCC entities, and from three continents. I especially enjoy operating on the satellites from cruise ships while on vacation. See my Cruise web page more for information about operating on cruise ships.

I also enjoy meeting in person with the many different people I have worked through the satellites. Pictures of a number of these operators may be found in Gallery 1, Gallery 2, Gallery 3. and Gallery 4.

E-mail - afmattis@hal-pc.org


Links to Useful Amateur Radio Satellite-Related Websites

AMSAT and ARRL

Satellite Operator Home Web Sites

Satellite-Specific Web Sites

Call Sign Databases

Pass Prediction and Keplerian Elements

Maidenhead Grid Squares


Antennas.us (Myers Engineering) UC-4364-328 Quadrifilar Helix Antenna

In the November 2008 issue of QST (page 72), Steve Ford, WB8IMY, reviewed the Antennas.us (Myers Engineering) 70-cm Satellite Antenna. In his review, Ford stated that the UC-4364-328 was superior to his eggbeater satellite antenna. Where my eggbeater suffered a few drop outs, the Antennas.us quadrifilar delivered remarkably stable signals. Antennas.us maintains a web site at http://www.antennas.us/ where you can learn more about their antennas. Details on the UC-4364-328 antenna may be found on the Amateur Radio Antennas subpage.

 


Antennas.us UC-4364-328 Quadrifilar Helix 70-cm Satellite Antenna is 6 inches tall and 3 inches in diameter

 

The Antennas.us 70 cm quadrifilar comes in several models including both LHCP and RHCP. I ordered the RHCP model. A 10-foot (3m) length of LMR-195 coax with a choice of UHF Male (PL-259), Type N Male, BNC Male, TNC Male or SMA Male connector feeds the antenna. I selected the BNC connector so that the antenna would connect directly to my ARR SP432VDG preamp. The antenna is available in a 5 watt model for $79.95 and a 50 watt model for $92.74. I selected the 50 watt model so that I can also use the antenna for uplink on AO-7 and VO-52. Total cost including shipping and handling was $104.

 

I decided to use the quadrifilar helix as a mobile antenna. I had been using the QHtenna 70-cm Turnstile Antenna (reviewed below) as a mobile antenna and wanted to see how the quadrifilar compared in performance. Because the quadrifilar was not designed for mobile use I had to create an adapter to attach the antenna to a standard mag mount.

 


Antennas.us 70-cm Quadrifilar Helix Satellite Antenna attached to a standard mag mount for mobile use

 

As of March 22, 2009, I have made 164 mobile satellite contacts using the Antennas.us quadrifilar antenna. As you would expect, the antenna performs best on high elevation passes, but the performance on lower satellite passes surprised me. I made two contacts on an eight degree maximum elevation pass of AO-51 while parked. I also made two contacts on a ten degree maximum elevation pass of AO-51 while in motion. This is impressive performance for an omni-directional antenna. I would describe the performance of the antenna on any satellite pass with 30 degrees or higher elevation as being absolutely excellent, usually resulting in 5 or 6 contacts even on congested passes. On many passes it is my uplink signal using a trunk-mounted Larson dual-band vertical that limits my ability to make contacts. I can hear the bird but not get in. Another plus with the Antennas.us qudrifilar is that the Larson vertical on the trunk does not desense the quadrfilar on the roof of the car and I have solid copy on myself in the downlink during most of my contacts.

 

I was so impressed with the performance of the Anrtennas.us quadrifilar that I ordered a second one for use in my home station. I mounted the quadrifilar on the roof of my garage and I only needed to add an additional 6 feet of coax to the 10 feet on the antenna to reach my station. The highest portion of the roof of my house is not on the garage but I wanted to keep the coax run as short as possible. As a result the quadrifilar does not have the lowest horizon possible but nonetheless it performs quite well. My other downlink antenna is an inexpensive MFJ quarter-wave ground plane mounted on the highest part of the roof. I use a preamp with both antennas and switch between them as the polarity of the downlink changes. My uplink antenna is an MFJ Pulsar dual-band vertical. It often desenses the quarter-wave ground plane because they are located close to each other; however, I have not experienced any desensing on the quadrifilar antennas.

 


Using Inexpensive Omni-Directional Antennas for a Home Satellite Station

For those satellite operators who have to deal with deed restrictions or restrictive covenants antennas are often the most daunting facet of their station. Certainly a large array of beam antennas is almost out of the question. And, if you are concerned about cost, the sort of dream station most satellite operators envision can be very expensive. I live in a subdivision with fairly strict deed restrictions, and my budget for amateur radio is in the hundreds of dollars not thousands of dollars. In the last year I have come up with what I consider to be an acceptable home satellite station using inexpensive low profile antennas.

 

I use very inexpensive MFJ quarter-wave ground planes for my downlink antennas. They are mounted in a location where a 15-foot run of coax can reach the attic. This eliminates the higher cost of mast-mounted preamps and downconverters. A 50-foot run of 9913 coax from the attic to my station below provides the final portion of the feed line.

 

In the case of my 2m downlink antenna I use a downconverter in the attic to convert the signal to 10m. There is very little signal loss at 10m using 50 feet of 9913. This allows me to successfully work VO-52 and AO-7 Mode B (U/V). For my 70cm downlink antenna the preamp in the attic provides enough gain for the 70cm signal to be readable after passing through 50 feet of 9913. The downside is that you must be very careful not to transmit into the downlink antennas or you risk smoking a preamp or downconverter.

 


A 15-foot run of RG8 connects ground planes to preamps or downconverters in the attic,

50-feet of 9913 runs from attic to the station below, MFJ-1754 is used for 70cm, MFJ-1740 is used for 2m

 

In addition to the MFJ ground planes I recently added an Antennas.us 70 cm quadrifilar helix antenna (reviewed above) to my station. This gives me two antennas for the 70cm downlink and I can switch between them as the polarity of the signal changes. While it is not as good as being able to switch between RHCP and LHCP on the same antenna, it does provide better reception than a single antenna.

 


Cushcraft AR270 has since been replaced by MFJ-1522 Pulsar ($79.95)

Almost any low-gain dual-band vertical will work; high-gain base antennas are focused more on the horizon

 

Almost any dual-band base/repeater antenna will work for an uplnik antenna. I have used both the Cushcraft AR270 and the MFJ-1522 Pulsar. The more expensive base antennas are designed to focus near the horizon and will not work as well for satellite use as the less expensive lower gain antennas. Another benefit for those facing deed restrictions or restrictive covenants is that the lower gain antennas are shorter and can be hidden on the back side of the house. I use my MFJ-1522 for both uplink and downlink when I work the ISS repeater. I can not always get into the ISS repeater when I am in the edge of the footprint, but the antenna allows me to make contacts, and I have even worked NA1SS twice.

 

The performance of my home station on the FM LEO satellites has been acceptable to me. I can usually hear the bird for 65% to 75 % of a pass. Due to the presence of trees, I have a lower horizon for east passes than for west passes. I have made contacts on an east pass with an 8 degree maximum elevation, and on a west pass with an 11 degree maximum elevation. Typically passes of 15 or 16 degree maximum elevation and greater are easily worked. On passes with greater than 50 degree maximum elevation it is not unusual for me to make 6 or more contacts.

 


HT and AL800 Antenna: An Excellent Portable Satellite Station

I do a great deal of operating on the FM LEO satellites with my Icom W32A HT and a Premier (Pryme) AL800 antenna. As of July 6, 2008, I have made 8943 satellite contacts using that equipment. The AL800 does not receive as well as an Arrow, but it is far more portable and does not attract unwanted attention. I wrote an article for the AMSAT Journal that describes how I use the AL800 antenna and the success I have had using it.

AMSAT Journal Article: HT and AL800 Antenna: An Excellent Portable Satellite Station

 


An HT with an AL800 telescoping antenna makes a very compact satellite station that can fit in your pockets when disassembled.

 


Using the MFJ-1800 2.4 GHz Antenna for a V/S Mode Downlink Antenna

When I read the excellent article by Drew Glasbrenner, KO4MA, (Mode V/S on AO-51: Something New Under the Sun, The AMSAT Journal, July/August 2005, pp. 14-16) and the short note by Aruni Perera, VE4WMK, (Field Day Fun in Canada, The AMSAT Journal, July/August 2005, p. 22) I decided that I needed to try this mode.  After all, I enjoy operating on the amateur radio satellites because I continually learn new things, and using a downconverter and radio wave propagation on 2400 MHz were two areas that I had no experience with. I ordered a K5GNA downconverter and was soon making contacts on AO-51 when it was in V/S mode.

 


The K5GNA downconverter with 2400 MHz dipole and corner reflector for working V/S mode is advertised as having 12 dBi gain.

 

The K5GNA downconverter with corner reflector is advertised as having 12 dBi gain; however, I have difficulty hearing the downlink when the satellite is below eight degrees elevation. I was looking through the latest MFJ catalog when I noticed a 2.4 GHz 16-element WiFi Yagi with an advertised gain of 15 dBi, and decided to order one and see how it compared to the K5GNA dipole and corner reflector. 

 

 

The MFJ-1800 antenna is actually quite fragile, and the instructions that come with it state that “The MFJ-1800 WiFi Yagi Antenna is intended for applications protected from the elements – out of the weather.   It can be made weatherproof by mounting inside a 3-inch PVC pipe.”  The MFJ-1800 comes with a standard “N” connector, and I used a CABLE-X-PERTS CXP1318FN 3-foot jumper to connect the MFJ-1800 to the K5GNA downconvertor. 

 


The MFJ-1800 antenna is actually quite fragile and should be mounted inside 3-inch PVC pipe if it is installed where it is exposed to the elements.

 

I was anxious to compare the performance of the antennas to see if the 15 dBi Yagi would outperform the 12 dBi dipole and corner reflector.  I used the MFJ-1800 to work three passes of AO-51 when it was in V/S mode.  On the first pass (16 degree maximum elevation) I was unable to hear the satellite; however, it was a Sunday evening and AO-51 may not have been switched over to V/S mode until late in the pass.  I tried a second pass (35 degree maximum elevation) and had much better results.  I could hear the downlink and managed to make four contacts; however, the downlink signals seemed to be weaker than with the dipole and corner reflector, and there was considerable fading.  I tried a third pass (14 degree maximum elevation) and heard many stations, but was unable to complete a contact.  Whenever I called another station, significant fading made it impossible for me to tell if the station I had called answered me. 

 

So, what did I learn about the MFJ-1800 antenna in this first attempt to use it for V/S mode?  Amateur radio operators soon learn that the gain numbers published in antenna advertisements are commonly exaggerated.  Also, note that in the MFJ catalog description shown above, both 15 dB and 15 dBi gain are used to describe the antenna.  My very limited use of the MFJ-1800 suggested that it may have less gain than the K5GNA dipole and corner reflector.  I discussed the performance of the MFJ-1800 antenna with two friends that have had more experience working with higher frequencies.  Both Andy Mac Allister, W5ACM, and Jerry Brown, K5OE, felt that using the 3-foot jumper cable to connect the MFJ-1800 antenna to the K5GNA downconverter might have caused significant signal loss.  Jerry’s exact words to me were “If you want to make a fair comparison, get a M-M N-connector and directly couple the antenna to the downconverter.” 

 


The MFJ-1800 antenna coupled directly to the K5GNA downconverter with an M-M N-connector

 

The March 13-19 and May 2-3, 2006 periods of V/S mode on AO-51 provided a good opportunity to test the MFJ-1800 antenna coupled directly to the K5GNA downconverter.  I was pleased to find that the MFJ antenna appears to outperform the K5GNA dipole with corner reflector.  Using the MFJ antenna, I operated an AO-51 pass with a four degree maximum elevation from the top of a parking garage where I had a clear horizon and made three contacts, and a five degree maximum elevation pass I made one contact.  I also tried a pass with a two degree maximum elevation from the same parking garage using the MFJ-1800 antenna and I heard a carrier on the downlink frequency, but was unable to detect any voice or modulation.  During an earlier period of V/S operation on AO-51, I operated from the same location on two eight degree maximum elevation passes and struggled to make two and three contacts with the K5GNA dipole and corner reflector.  On higher elevation passes I did not observe any significant difference between the two antennas.  With either antenna it was common to make five to eight contacts depending on how many people were working the higher elevation passes.

 

I also observed that it was necessary to rotate the K5GNA dipole with corner reflector quite frequently to compensate for fading of the downlink signal.  The MFJ Yagi antenna did not appear to be affected as much by fading and required less rotation.  I must also state, however, that the K5GNA dipole with corner reflector is very sturdy and rugged, while the MFJ-1800 antenna is somewhat fragile.  Another drawback to using the MFJ-1800 is that it is quite directional, and I sometimes lost the bird for short periods of time until I repositioned the antenna to point more directly at the satellite.

 



The bottom line is that the MFJ-1800 antenna allows me to work lower elevation passes of AO-51 in V/S mode than I can with the K5GNA dipole and corner reflector.  The slight difference in performance of the two antennae on high elevation passes may result from the directivity and difficulty aiming the MFJ Yagi directly at the satellite. My purpose in posting these observations is to make others aware of this antenna and its possible use in working satellites.  After all, experimentation and learning is what satellite and space communications are all about. 

 


E-mail - afmattis@hal-pc.org

Created: October 26, 2002 by Allen F. Mattis
Last Updated: December 24, 2011