Jan 01


I wish everyone a good, happy, healty and prosperous 2017!


Bjorn de PD5DJ


Dec 04

AAI N1201SA Vector Impedance Analyzer

Recently I bought a very handy tool for measuring all my antennas and  “filters” up to 2.7GHz!

Its an new Vector Impedance Analyzer for the company AAI, there are 3 versions of this analyzer, the one I bought is the N1201SA..

– Model: N1201SA
– Working currency  140MHz~2700MHz
– Stepped frequency  1kHz
– Display  2.4cun TFT trdp
– Resolution ratio 320*240(QVGA)
– Battery capacity: 2000mAH(7.4Wh)
– Power consumption <1.5W
– Charge current 400mA
– Charge port USB
– Auto power off can be set 5-60minutes
– Measured parameters  resistence  reactance  standing wave s11
– Resolution ratio 4 number
– Frequency accuracy about 5ppm
– Connector SMA-K
– Impedance measurement range: 0.1~1000
– Standing wave measurement range:1.000~65
– S11(dB)measurement range: 0dB~-60dB
– Working temperature:0~40 degree
– Atmospheric pressure:860hPa~1060hPa


User manual can be found here: AAI N1201SA Manual


This Analyzer made it possible to measure some of my already built antenna creations..

For example an simple Groundplane antenna for 23cm, that was made from calculated dimensions, for 1250MHz,.

As seen on the analyzer,, the best SWR is on 1245MHz, NOT BAD! 😎


More measurements have been done on my 13cm Helical.
This time I was even more impressed!

I have designed/rebuild this antenna from VE2ZAZ his design, and added more turns.

First image:

Shows a broad sweep across the 13cm band, as you can see the SWR stays widely under 2.0 so thats good..
The hops, are caused by the ~2m length of Ecoflex-10 coax it is connected to.


Second image:

Now the range where the antenna is supposed to work in, that is in the range of 2400 – 2404mhz
you can see it is really not bad at all!, the best SWR is on 2408MHz,,

Overall I am more than happy with these results! 🙂



Nov 23

Projects added!

I have finaly found some time to document some recent projects!

You can find them on the project pages animated-arrow-image-0032

Nov 12

13cm S-Band System added to my satellite mast

Today I finished the 13cm S-Band Project

It consist of my newly build 13cm 34 Turn Helical Antenna in combination with the Icom AG-2400 that I previously renovated.


satmast2016 icomag2400

Nov 11

New 13cm S-Band Antenna

Today I have finished a new antenna for S-Band downlinks..

Since the antenna has to go on the satellite mast, and there is not much room for a dish, I decided to start off with a Helical antenna.

I have build several in the past, and took the design from VE2ZAZ

Back in 2005-2007 I had good experience with this helical design, so I did not hessitate and started to build one again.
Only with some more Turns, to be precise 34 turns.. (That is what you max get from a roll of 5m 6mm2 wire from the store 🙂
Theoretical gain of 19dBI

After building this helical, I have set it up for testing, and the SWR was good enough 1/1.3 on 2400MHz 🙂 so no tuning needed further here..

Checkout my project page for more information about this antenna: 13cm S-Band Helical Antenna


Nov 08

Portable Satellite system

This project is from a couple of years ago, begin 2014.

Most of our fieldday trips are HF or sometime oc’casionally VHF related..

But I wanted something new to bring to with me with these trips..

So I thought, Why not build a portable Satellite system!

So I did 😉
Well I did but I had just 2 months to build all before the first fieldtrip started in May that year

The system consisted of the following parts..

  • Portable mast – Homebrew
  • Antenna Rotating system (KR400/KR500)
  • X-Yagi 2m – Homebrew
  • X-Yagi 70cm – Homebrew
  • Polarisation switchbox – Homebrew
  • Antenna Tracker/Interface – Homebrew

As I build many antennas in the past, the Yagi’s I build at the latest minute, but I did try a new element mounting method that I wanted to try for a long time, specially for field days.

For the Antenna tracker I wanted to try something new, I did not want to make another ordinary tracker hooked up via USB or Serial cable to the PC.
No I wanted to just the Phone or Tablet to control it via Bluetooth!
I Just started playing with programming Android apps, So I though “why not combine it!?”


Overview of the complete Antenna system consisting of an VHF X-Yagi 6-El, and a UHF X-Yagi 10-El



Closeup of the switchbox, consisting of 2x CX-120D relaysportasat2


Detailed overview of the antenna construction, note all elements except the Radior are mounted thru the boom.
I have CNC drilled holes thru Nylon bolts where the elements are fixed in.

With a simple nut mount method you can quickly assemble and disassemble the antenna.

portasat3 portasat4


And this is the app, At the moment we speak the app is totally revised.
As you can see, no manual controls at the Control box, just bluetooth connected to phone/tablet or PC.

On my Netbook I had SatPC32 running with Bluetooth connection, worked like a charm!


Nov 04

Rotator Interfaces, and Android App

Some time ago, I have made a “blackbox” version of my Rotator Interface..
I used that interface to controll a satellite setup on fielddays..
Just PC control over bluetooth.

Last night, I’ve implemented the “blackbox” commandset to my regulator interface software..

Although the connection of the interface is only possible via USB (RS232), I have found a workarround to get the interface connected with bluetooth 🙂

This Bluetooth interface the HC-06 is connected to a USB-Serial TTL board. To my PC..


For most Serial devices like CAT control, and my Rotator Interfaces, I use a progam called VSPE.
This program is capable of creating virtual serial ports, and split ports, and even redirect ports.

For Example:

My Rotator interface is active on COM3

I have created a splitter with a Virtual Port on COM13

So multiple programs can connect to COM13 simultaniously, and VSPE directs all traffic from and to COM3

Now my Bluetooth/USB combination is active on COM16

In VSPE I have created a Serial Redirection

COM13 is redirected to COM16 and visa versa..

Now when my Android device is connecting the Bluetooth module, it opens up COM16, redirects it to COM13, and the splitter will connect it to COM3..


And when all is setup and running. this is what my Android app will do with my Rotator Interfaces 😉

Nov 04

Polarisation Switchbox (Temporarily)

For my X-Yagi’s I have made a simple switchbox that switches between Horizontal and Vertical polarisation.

For regular transponder work this is enough, because you switch between the outermost polarisation difference..

Difference between Horizontal and RHCP/LHCP is just 3dB, same for vertical..
But the difference between Horizontal and Vertical is 30dB!

If you are listening with a regular yagi, you will notice a big drop in signal during the pass, If you could switch the polarisation you WILL hear the difference ;-).

I regular have passes that are not hearable for example on Vertical, and S9 on horizontal 😉

My polarisation box consists of 2x Thotsu CX-140D relays, With RG-223 coaxial cables.. and N-Connector Flanges..
The remote is quite simple.. just 2 switches that switch them on or off.




Oct 23

New Satellite Antennas

After finishing my rotator interfaces, I have started with designing and building my satellite antennas.

First of all, I am restricted to a maximum 2m boom due the placing of the satellite mast, near de edge of the roof.

Now looking for a basic design that fits on a 2m boom.

Started gathering information on antennas, my favorites are DK7ZB antenna designs..
They never let me down in the past, so a thumb rule.. “Why change a winning team!?”

As for sats, they operate in a very wide frequency range, specially on 70cm..
Most GOOD designs are mostly low impedance ones, and they are very likely to behave very narrow band.
So I looked for a broadband design.

Most 50ohm designs of the DK7ZB are broadband,, In the terms, of < 1.5 VSWR on the band edges.

I took one of those designs and start playing with these designs in EZNEC (Wonderfull software from Roy Lewallen W7EL)

As the designs on DK7ZB are optimized to work on the lower portion of the 70cm and 2m band (432 and 144mhz) I first needed to rescale the designs to the upper part of 2m (145.900mhz) and (436mhz).
These portion of the bands, are mostly used for Satellite operations.

But still these antennas have to be very broadband, because of for example AO-7 is using 432mhz for uplink (TX!) so a good VSWR is still needed here.

Also a big challenge is to place all elements in the way that a X-Yagi can be made, and also a boom/mast clamp can be mounted.
Here I had to play with the element distances, and after every tweak I had to observer the sidelobes etc. etc..

Anyways, I have came up with some decent designs, and so time came to build them!

As for the DK7ZB designs, In the past I always semi constructed they antenna for testing..
But after building loads of these designs, I have build the 70cm version straight away.

After building these antenna’s, I have measured the VSWR, and they where spot on!, Just perfect on the desired frequency 😉


Here testing the 2m version


Finished contruction of the 2m X-Yagi

2mantennaready  Finished the construction of the 70cm X-Yagi70cmantennaready

70cmsatdipole satarray2 satarray1 satarray3


Oct 20

Complete Station changeover! Back to SATS!

Hi all,

It has been some while ago since my last posting, but lot has changed here.

Several months now I am facing big QRM on HF, lots of PLC and other QRM is killing my HF pleasure 🙁

The Telecom Agency has been here 3 times searching for all these unwanted QRM, but with no luck “yet”, but my case is not closed yet.

Anyways no time to sit still and do nothing! 🙂

Winter is coming, and homebrew season has started here!

So I thought “Why not move up!”

Up has now 2 meanings :), Up in Frequency, and Up in working Satellites again!

For that I needed to modify A LOT! to my station..

First of all, I neede a Azimuth and Elevation Rotator, (I didnt want to loose my “big” mast rotator so bought a second hand refurbished one from a well know radio amateur Karel van Puijenbroek (PD2BNH/ON2KP) he does excellent refurbishing in many brand know rotators.
I still had my Elevation rotator, so that one came on top of this new rotator.

Also I needed a new Rotator interface, Since the old one is used to drive my “big” mast, I needed a second one, dedicated just to the Satellite mast.

But then the challenge came to find the exact enclosure I have used before for my other unit.. 🙁 bad luck out of production…

As I wanted two identically interfaces, I decided to build 2 new ones..





Some 3D printing was needed here, since I had a short on metal Capacitor mounts, I decided to make a simple 3D design and print them myself.. looks very nifty dont you think 😉rotcaps



A closer look at the inside interior, not much has changed here, only I replaced the screw type terminals to connectors, Easy to get the PCB in and out for repair if needed.

rotinside1 The Overal view of the interface, I really like these cabinets, they came from www.eltim.eu you can find them as MODU electronics cabinets, Economica.rotinside2


Second controller almost finished, just waiting for new PCB’s and BLUE/WHITE LCD’s! 🙂rotfront2



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