Ham Radio

Wednesday, July 15, 2009
Dual Band Satellite Yagi
It's been just over a week since I installed the 10-element yagi in the place of the 435 MHz IO loop and as you can imagine, I have been testing it out at every opportunity. Unfortunately like the previous experiments once again I was disappointed with this time 10-elements against the single IO-Loop's performance. The new yagi appeared to be poor in comparison.
So, now that I have finished for the summer holidays I decided today would be the day that I got to grips once again and sort out my home brew dual band satellite yagi/beam antenna. I had been toying with scrapping the driven element and replacing it with another IO- type loop. I dropped the antenna and set about fitting the 435 MHz loop, I used the original element/boom plastic clamps and with a bit of measuring and a few adjustments I grafted in the new loop as the now replaced driven element (DE).
I then used the original (now spare) driven element as a reflector and re-positioned it behind the loop at the required gap. I now had 6 elements (D) in front and 2 elements at the back of the loop (Ref). I ended up with a couple of spare elements which will be used in any future experiments that I am sure I will be trying.

Once I connected the feeders I set the 435-MHz IO-Yagi to vertical polarisation fixed above the horizontally polarised IO 145-MHz beam. I decided to set the 435-MHz antenna vertically to see how it performed receiving the FM Sat's such as AO-51, SO-50 and AO-27. I will be busy testing to see the results over the next few days.
I tried it out on a couple of local FM repeaters on 433 MHz and noticed that one repeater was S-5 on my Co-linear (Vertical) whilst up to S-9+30 on the IO-Yagi. The modified yagi seemed to be putting the RF in and out in the desired direction and giving a good front to back ratio. Before I can complete the evaluation, I will see how well I get up into VO-52 vertically polarised at 30 degrees elevation. Don't be too surprised to see the IO-Yagi part of the antenna set up back to horizontal in the next post!
posted by Simon Davison @ 5:08 pm  
4 Comments:
  • At 9:14 am, Blogger g4ilo said…

    Interesting experiment. I wonder if the real reason for your disappointment is the sharper beamwidth of the long yagi means it's much more critical to point it exactly at the satellite? The broader IOio design lets you aim in the general direction and still get some RF where you want. I await the results with interest.

     
  • At 7:09 pm, Blogger 2E0HTS Simon said…

    Hi Julian, thanks for your comment it is always good to hear from others especially when its good advice!

    I believe your view on the antenna being more critical in aim than the previous broader pattern is spot on and I can see how the results could show this. Now that I have been playing Satellites for a while I have hopefully got better at aiming the antenna in the right direction hi hi. The IOIo has been a good apprentice op antenna and with a bit of luck I am ready for a more directional ant like this latest one.

    Today's results have been good so far, excellent reports via VO-52, but still struggling with the FM birds. I can hear the FM Sats slightly stronger with the loop yagi rather than the dipole driven element. Its early days but fingers crossed it appears to be working quite well so far.

    Will be posting the information after more tests.

    73 all the best and keep up the good work. I always enjoy reading your posts.

    See you on Planet Ham.

    Simon

     
  • At 4:52 pm, Blogger M.T. Jones said…

    I'm considering building an IOio for sat comms. Can you forward any further info?

    Thanks!
    KK4AXX
    Mobile, AL USA
    Grid EM50vo

     
  • At 8:58 am, Blogger Simon Davison said…

    Hi tnx for the comment follow the link for build dimensions
    http://2e0hts-hamradio.weebly.com/-radio-equipment--homebrew-antennas---download-area.html
    Good luck hope to hear you via satellite soon. Best 73

     
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