Tag Archives: dish

Another strange constellation (Update)

February 6th, 2014

While performing my beacon check on December 16th, 2013 at 8:30 UTC, I stated that all beacons seemed to be at a normal level. Except, when looking for DB0FGB (JO50WB) with the dish heading 85°. There was a constant carrier of about 20 dB 15 kHz up, keying F1ZBK (JN38BP). Expecting a big signal, I turned the dish to France. But the beacon was only 15 dB with QSB, when beaming directly to it at 228°. Then I turned the dish back to 85° and noticed, that HB9EME (JN37KB) joined the party.

2013-12-16 09_30 F1ZBK HB9EME 85deg

DB0FGB, F1ZBK and HB9EME with dish heading 85°

The rain radar didn´t show anything unusual and the F5LEN Refractive index forecast for Europe promised only marginal tropo conditions for this area. Only DL7QYs Condition Index for south Germany has been on a level of 7 (1 = poor; 10 = extreme).

2013-12-16 09_00 F5LEN index

F5LEN Refractive Index

DB0FGB was a bit above normal at about 15 db with little QSB up and down. F1ZBK was constantly at 20 dB, when beaming 85° and around 15 dB with QSB heading 228° (direct). HB9EME was up to 20 dB in 85° and peaking 15 dB in fast QSB when beaming 198° (direct).

Green: Paths from Mainz to the beacons
Orange: Paths of the beacons to the area of the supposed reflection point

I checked HB9BBD, F5ZBS, F1ZBI and others, but couldn´t see any similar effects. The angle was very small. When turning the 3 m dish 5° left or right, the signals disappeared. These conditions lasted for about one hour.

Path DJ5AR to DB0FGB (by AirScout)

Topographic profile between DJ5AR and DB0FGB

The horizon in 85° is about 80 to 90 km off. A plausible explanation could be a strong troposheric duct between the beacons and a reflecting topographic formation.


In issue 2/14 the german magazine “Funkamateur” published an article by Matthias Hornsteiner, DG4MHM “Prognosekarten für troposphärische Überreichweiten” (Prediction maps for troposheric ducting). Matthias explains the basics of ducting and analyses the models, the well known refractive index maps of F5LEN and W. Hepburn are basing on.

So I had the intention, to ask him about a possibility for a reconstruction of the wheater constellation of that day. I have to thank him very much for his comprehensive answer.

As Matthias explained, the situation, shown on the map, was quite common for this, as he describes it, “anti-winter”. But it holds the possibility, that warm air might glide onto cold air at ground level. And indeed, when he reviewed the data of weather balloons launched at Stuttgart on that day, he found indications for a strong inversion in an estimated level of 400 to 600 m over south Germany. That matches!

In a distance of 200 km from here, the the topographic profile shows a formation, high enough to reach the level of this duct, as well as the mountains of the Fichtelgebirge do, where DB0FGB is located. The distances from Mainz to the area of the supposed reflection point is between 200 and 250 km. From F1ZBK and HB9EME it varies between 400 and 500 km. So the total path should have been between 600 and 750 km.


Opening September 21st 2013

September 21st, 2013

While performing a last beacon check before going to bed and all local beacons were quite normal, I took notice of a weak carrier 1 kHz up of F1ZBK on 1296.855 MHz. After optimizing the antenna and using a narrow filter I heard EA2TZ in IN93BF over 1073 km for the first time ever.

2013-09-21 20-50 EA2TZ

Left signal: F1ZBK/B, right signal: EA2TZ/B

 EA2TZ/B as received by DJ5AR over 1073 km on 23 cm

After posting this information in the ON4KST chat, Matej, OK1TEH sent the phone number of EA2TO and told me that Javier is currently QRV on 23 cm from IN83. After exchange of a few SMS he came back on my CQs and we could complete a QSO: A new DXCC, a new square and a new tropo ODX of 1173 km on 23 cm!
When closing down the station I had a quick look on 70 cm. There he was again: EA2TO in SSB. We had a nice chat and for me: A new DXCC, a new square and a new ODX of 1173 km on 70 cm!

Only 2 QSOs tonight, but I am very happy with it.

Rainscatter on 23 and 13 cm

June 20th, 2013

While performing my daily beacon check, a strange constellation around 1296.850 MHz appeared on the display of my SDR. The dish was turned to 254° at that time, to look for F5XBK.

2013-06-19 RS F5XBK F1ZBK ON0NR HB9EME

From left to right: F5XBK, F1ZBK, ON0NR, HB9EME

Combined with strong QRN and radar noise I could copy F5XBK in JN18JS quite normal via tropo but also F1ZBK in JN38BP, ON0NR in JO20KJ and HB9EME in JN37KB via a rain scatter point in JN39LP. Later DB0GP in JN48WQ and DB0AJA in JN59AS could be heard too.

Then I continued to have a look on 2320 MHz where DB0UX in JN48FX, DB0FGB in JO50WB and DB0MJ in JO31UB could be copied via a scatter point in JN39JR.

Beacons heard via rain scatter on 23 and 13 cm

The map shows the location of DJ5AR in Mainz (green marker) in relation to the scatterpoints (blue markers). The paths to the beacons on 1296 MHz are in light blue and on 2320 MHz in dark blue. For that time heavy thunderstorms with flooded roads and cellars were reported for the area of Hermeskeil in JN39.

ISS bounce V: The QSO!

May 23rd, 2013

STS-133 International Space Station after undocking 5

(Copyright by NASA [Public domain], via Wikimedia Commons)

After a lot of tests and improvements have been done in tracking the doppler shifted signals, Jan, PA3FXB any I had another try around 1296.300 MHz this morning. Both of us performed compensation of the own doppler component as well in receiving as in transmitting. We agreed in using  the EME QSO protocol and periods of 30 seconds.

PA3FXB as received by DJ5AR

Jan appeared within my filter bandwidth as soon as the ISS became visible to both of us. His signal strength was peaking up to nearly 20 dB above noise and was easy to copy. The tracked frequency seemed to be stable until the ISS culminated. Then the variation of the doppler shift became so rapid that the compensation mechanism was not fast enough anymore. But that happened to the very last part of our QSO while we were transmitting our final 73s. So I can state that the best signal quality can be expected during the ascending and the descending parts of the pass.

In the meantime I received Jan´s recording. Listen how DJ5AR sounds on his side:

DJ5AR as received by PA3FXB

Many thanks to Jan for his cooperation and his patience in numerous tests before.

This success is dedicated to our fathers, who suffer from the same disease!

If you are interested in a try, do not hesitate to contact Jan or me. You can find us in the HB9Q 1296 MHz EME logger or in the ON4KST microwave chat, when QRV.


ISS bounce

April 7th, 2013

Tonight Jan, PA3FXB and I tried, what we were discussing about for quite a while. There was a prediction of an ISS pass shortly after local midnight and both of us had no other appointments. So we agreed that Jan should make a transmission on 1296.300 MHz as soon the ISS became visible to him and tracking it as long as possible. My part was to monitor the pass of the International Space Station on my SDR. We used 3 m dishes on both ends and Jan had approximately 375 W in CW.

PA3FXB via ISS Beginning

PA3FXBs signal at the very right

Here is the result. Jan appeared with a relatively strong signal (on the very right), faded out and came back with weaker signal strength. I interpret it, that the first appearance was backscatter and the second was forward scatter, what has to be discussed. Doppler was extremely strong and more than 40 kHZ at the beginning.

Time for DX

June 19th, 2012

The NAC is always an opportunity to work stations from Scandinavia on 23 cm. Yesterday I had QSOs  with Frank, IK3HHG and Giorgio, IK3GHY in JO65 over 570 km. The signals were quite poor compared to QSOs before but were accompanied by strange pings – lighting scatter as Henning, DF9IC explained me tonight. So I wondered how the conditions would be this evening and turned my dish to the north. I started with DL0VV (JO64AD / 538 km). After a while I heard OZ9KY (JO45VX / 683 km) calling CQ and could add a new square to my collection. He was followed by SK7MW (JO65MJ / 691 km) with another new square and new country for me. In the meantime more and more stations from the UK logged in at the KST chat. Now the dish was turned to 298°. John, G3XDY (JO02OB / 547 km) could be detected on .215 and after a meep in the chat he turned his antenna to me. John produced a big signal in ssb peaking here 57 with little QSB. It was the second new country for me tonight and square #50 at all on 23 cm.

gn all

The dish is up and running!

May 1st, 2012

After mounting the dish last evening, I was very impatient to see how it works. So I installed the controls for the rotator, fixed some meters of ECOFLEX 15 cable in the morning and started checking the beacons on 23 and 13 cm. It was no surprise but very satisfying that all of them were much stronger compared to the old 1.2 m dish. In the afternoon I had the initial QSO with the new antenna on 23 cm with Giorgio, IK3GHY in JN65DM. As I now know, I only had 5 W but Giorgio heard me with 539 anyway. My report for him was 559 and at the end of the QSO I could copy him in SSB too. Later I had a sked with 9A1Z in JN86DL. The signals weren’t strong enough to complete a QSO but we were able to detect them in the noise. So we will have another attempt when the preamp will be installed and my linear is finished.