OE8WOZ

Hairpin filter for Es'Hail 2 (AMSAT P4-A, QO-100)

My first experiments to set up an hairpin filter for the 13cm band (2.4GHz). The deal is to get the right passband and proper SWR - ideally w/o trimming. So I had to do some trial rounds to get the proper parameters for the PCB material my supplier is using.
I think I hit it quite well, see yourself (S21/dB, S11/SWR).I set the frequency on purpose a bit "upwards" to get the maximum distance to the LO frequency to filter out. As shown, the filter can so ~25dB for a 2m LO setup and ~40dB for 70cm LO setup. So I will go for 70cm LO which will ensure I keep out-of-band bins on transmission 40dB below the in-band bin.
This measurements are w/o additional LNA mounted, next is to add ERA-2 amplifiers and biasing/12V supply to come to ~0dB attenuation in the passband region:
 /ownpics/Hairpin_2400mhz_nogain.png
/ownpics/Hairpin_2400mhz_s21.JPG/ownpics/Hairpin_2400mhz_s11.JPG
It will fit in a standard metal box for shielding (measurements in mm):
 /ownpics/Filter_PCB.JPG

Hairpin filter for the 9cm band:

For my 9cm transverter project I require a simple to use filter to extract the proper USB after mixing. So I re-used the data for the 2400GHz filter and scaled it properly. I ensured that a 2.4GHz and 3.4GHz filter is used on the very same PCB (and I separated it manually myself).
I have to say that the higher band is harder to design and to hit the right frequencies. At least the frequencies are a bit low, so I can cut the PCB traces a bit to tune it into the 3.4GHz region. The 9cm band is probably also the reasonable limit for using standard (but thinner) FR4 material...
This measurements are w/o additional LNA mounted:
/ownpics/Hairpin_3400mhz_nogain.png
/ownpics/Hairpin_3400mhz_s21.JPG/ownpics/Hairpin_3400mhz_s11.JPG
 The PCB size is the same as for the 2.4GHz filter above.
For development, I use my self-made Excel script to generate the structures for simulation and PCB layout (direct import as copper layers). Then I simulate everything in QUCS Studio.
/ownpics/Microstrip_Development.jpg

My experiments with microwave antennas from 1-24 GHz (mostly Vivaldi)

I did quite some design experiments with "Vivaldi antennas" (or correctly named tapered slot antennas - TSA).
Some are for large bandwidth, some are for power. I often use them for experimental setups as they are much leaner than parabolic dishes or yagi antennas and still provide a good SWR as load and at least "some" directivity.

My best variant "Vivaldi V5" for the 13/9/6/3cm ham radio bands

 /ownpics/Vivaldi_V5_Size.jpg/ownpics/Vivaldi_V5_SWR.jpg
For the main bands it is obviously a λ/2 antenna with quite nice and flat SWR over a broad range.
As you can see it is also resonant on 23cm (presumably λ/4 only), but I didn't do further investigations there.
I have some antennas left, if you are interested pls. contact me.

Coming soon

  • a compact 9cm transverter (ZF: 144MHz/<=30dBm, RF: 3400MHz/>=13dBm, LO: 3256MHz/~13dBm)
/ownpics/TR3400.jpg
          Some promising gain and noise figure measurements...
/ownpics/Noisefigure_3400MHz.jpg
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