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Everything posted by Bosse

  1. Because different receivers and transmitters uses different brands of connectors, and cable connectors wich you might use, comes in different brands, it is not useful to express recommended cable-lenghts in inches or millimetres, reason is the dimensions of the connectors are not completely standardized and exact dimensions are essential, when making a matched transmission cable for use with equipment wich is not perfected. However, for my "old type" lawmate receiver, I have made a goof proof patch and I used Radiall connectors and RG-174 cable from Bedea. Components used are ( in ELFA n
  2. Ok, Feeling like I need to come back to this subject. I have not had the opportunity to make any flight or other tests recently. I am still conviced Bi-quads are great, only remember they are polarized, horizontally or vertically or at some other weird angle inbetween, you migh find great. Bi-Quads are the turbo-version of patch antennas in my oppinion, let it be they are somewhat more awkwarad in design, still they are quite simple but with high gain. Whenever I have some test results, I will come back on this subject. Best regards, Bosse
  3. As I assume Cyber-Flyer means, It is always best to make empirical studies and adjust the setup accordingly. Empirical approach is the final blow on a problem of this kind !!! However, strictly empirical way of looking at a problems, does not give as much feedback as the theoretical way does. Both are completely essential. Best Regards, Bosse
  4. Hello Cyber-Flyer and everone else ! Terry, I assume, you have already found out that you can use a wave-guide also known as a horn, not only as an antenna by itself, but also as the active element in a dish or parabolic antenna, wich is also the truth for some other antenna designs. (they are called parabolic but how many of them are parabolic and not spherical ?). The horn itself has a quite narrrow reception aperture, or beam-witdth as people like to call it. I have no numbers right now but you will easily find out if you look around on the net, I think it is less that +/- 10°. The
  5. You are right about the wind, or as I think of it, the turbulence. Best Regards, Bosse
  6. Cyber-Flyer. I think I know the reason of your objection now hehe. I guess you say "work with half wave-lengths" I say (or my source says), "work with ODD multiples of 1/4 wave lengths" Well, it is excactly the same, with one exception: the first multiple, or the first maximum you will find in the cable. Essentially I guess we agree ! Best Regards, Bosse
  7. It is quite possible a transmitter does not have an output impedance of for example 50 Ω, enventhough the manufacturer says so. Same goes for coax-cables. 1/4 wave gp antennas might not have an impedance near 50 Ω just because 1/2 wave ones do. This would force us to carefully adjust cable lenghts unless we use Baluns, wich would require us to know the excact impedance anyway. I wish I could afford a DIP-meter, Field-Strenght meter and a Network Analyzer. I would gladely make exepriments and tell you then. This is old well documented stuff. However, since it is a bit complicated, i
  8. Terry, About Di-poles with reflectors. I am sorry I can't tell. However, I do have a extremely strong feeling the reflector, or director, if used, does not change impedance. It should be 73 Ω according to my feelings I guess you have looked at one of those round antennas with a di-pole as driven element and one round reflector as well as a round director ? I think those looks good myself. However, right now (just like the wind changes), I look more at wave guides (horn designs), for my next receiver antenna. Best Regards, Bosse
  9. Last thing I want to do is to make you sour but the "Odd multiples of 1/4 wave-lenghts" rule is what I have read. I could be wrong. (that happens regularly) I would be grateful to be enlightened. Best Regards. Bosse
  10. That's why I was smart enough to add "theoretically" To be safe, it is always best to use theoretically matched cable lengths. If you have access to instruments, you can tweak your setup from that point and get the best results. If you use almost perfect components, cable length will affect performance just like the books says. (just keep lengths short and forget about the millimetres) If you start wrong, from a theoreticl pow, and you can not check your performance with help of instruments, you might find it hard to find the right formula of success. Best Regards, Bosse
  11. I mean, theoretically, if you use Yb2normal's ground plane antenna design, you can forget about excact transmission cable length, just keep it short to reduce loss. Best regards, Bosse
  12. I mean it should be odd multiples of one quarter of one wave-length. Best Regards, Bosse
  13. The length should be odd multiples of one wave-length (approx 20.5 mm). You should concider whole transmision cable as being the whole length (including connectors), that is whole lengt of shielded transmission cable including all connectors, even those in your bought equipement. If the load on the reciver or transmitter is perfectly matched, this is not theoretically important however. Best Regards, Bosse
  14. Only by looking at a ground plane antenna, I get the feeling it is un-balanced. It has at least four ground plane radials and only one radiator. I never try to be smart. I just like to discuss and share what is important to my and yours interests. Best Regards, Bosse
  15. You might wonder why I spend time in investigating why this antenna works so well. I think it is very important to to investigate reasons of good results, thats all. Discussing reasons of less positive results can be interesting too, but this is so much more interesting. Best regards, Bosse
  16. Hi Mike. I looked at your pcb layout and software design. I have not analyzed it thoroughly but on a brief look, it looks good. The requirement of a FMA co-pilot might not be written in stone. By designing the airframe properly, no FMA co-pilot would be required. If rudder throw is limited to a degree suited for the airframe, it should work anyway. I have indeed tested the FMA co-pilot with good results but it is not a requirement for level flight after all. Old principles in aircraft stabilization still applies. Dihedral and properly selected airfoil makes the airframe dynamically
  17. Heres a pic of one, taken at ESCF in MSFS2002 Best Regards, Bosse
  18. I have seen those original photos from Iraq. To me, it looks just lika a hoax. Best Regards, Bosse
  19. I use one from Traco Power in Switzerland. However it might look expensive, it seems to work great. They have a whole range of DC-DC converters. Mine converts 4.5..7 V to 12 V @ 500 mA. It seems like it does not transmit noticable interference to either its leads or to the air. Best Regards, Bosse
  20. You might wonder why I do not build a pusher instead. Well, it is all compromise. I require a scale model, STOL performance and some interesting historic records, as well as suitablility as arial fotage airframe. Not to mention I got a real Fi-156 only 2-3 km's away and I have free access to it every day Best Regards, Bosse
  21. I agree, a very good thread ! The airframe is important. Currently, in my first stumbling steps in arial video fotage, I use a very old design trainer from the 60's. If properly trimmed, it flyes perfectly stable and it can in fact be flown without control (free flight). It can carry a payload of 500 grams without much difference in flying characteristics. It is a Graupner Taxi (I). However, It is not perfectly suited for my personal requirements, so I will soon start building a new airframe. I will build a Fi-156 Storch semi-scale model in 1:6 or maybe 1:5 scale, and use it not
  22. I found out the other day, that the angle between the elements of a dipole, governs the impedance. 180° gives 73 Ω and 90° gives 36 Ω. The ground elements of a grund plane antenna, are bent to an angle of 135° relative to the active elements (or -45° relative to horizontal plane) , wich gives an impedance close to the wanted 50 Ω. Conclusion: Yb2normal's Ground Plane Antenna is likely to have an impedance close to 50 Ω, wich is good. Best Regards, Bosse
  23. Per, Have you had any success in contacting your CML distributor (wich should be "EU components"). I talked to their Girl in Stockholm, guarding their phone. She couldn't even confirm they are in fact a distributor of CML components here... At first she said (after some talk with some person sitting next to her, they would indeed sell to private persons, depending upon what products in quesion.. ?? But when I mentioned the particular chip I wanted, She said they don't have it and they don't sell to private persons anyway, Djävla skragga (darn scrag...) They do not reply on e-mail eit
  24. Ensignnolo, I am with you. People tend to see threats in things that are hard to imagine or understand. Journalists love to express new kind of threats in order to make their paper rag more interesting. If anyone wanted to spread havoc, he or she would probably use simple methods, just like they have done so far. I do not want to mention what they might do in the future. However, delivery system of a mass destruction weapon, will probably be an ordinary human, possibly willing to become a hero. Such a system is very easy to program, you just have to tell it what to do, in plain speech.
  25. I'm with Terry. I think gps feedback is "cheating". It has advantages. However, it it threoretically not a robust system. It is potentially a "moment 22" system. A radar does not have to get position data from the objects it is supposed to track. If it was, it would of cource be redicoulous from a military point of view. Extremely light model aricrafts, or other model aircrafts wich you might not want to put a GPS recevier in, can not be tracked by a system relying on GPS feedback. Best Regards, Bosse
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