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  • Users: blueandwhiteg3
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  1. blueandwhiteg3

    Help With Reducing Adhesion With Casting Tooling for Zinc & Aluminum

    I am trying to prepare some casting tooling to cast zinc and/or aluminum. My goal is to cast a shallow parabolic dish, approximately 70 cm diameter. I have at my disposal a friend who's an expert metalworker, but he doesn't know casting, and I'm not entirely sure what I want them to produce to...
  2. blueandwhiteg3

    Dual-reflector system on a parabolic for many feeds

    I have been trying to determine the best way to handle many feeds / radios operating on a single point to point link, as much as 10 to 20 feeds would be nice, operating in the 5-6 GHz range. I have been thinking that a dual-reflector approach might work, one small secondary parabolic-like dish...
  3. blueandwhiteg3

    Problems with re-using Ka/Ku band dishes for 5-6 GHz (C-band)?

    I have a number of Ka and Ku band dishes I'd like to consider re-using in the 5.2 to 5.9 GHz range for point to point links. I would replace the feed with a centered feed of some type, for a more traditional parabolic approach, rather than the offset approach. However, I observe the dishes are...
  4. blueandwhiteg3

    Why are commercial satellite dishes oval - not round?

    Basically all small and medium satellite dishes (1 meter and less) are not quite round. Some dishes are oval and horizontally wider, vertically taller for multiple feeds, wider angles, etc. Others are vertically taller. I have several dishes here, from the little 18" DBS dishes to big 1 meter...
  5. blueandwhiteg3

    Wide Angle Multi-Radio Coverage via Simulsat / Offset Parabolic?

    I'd like to cover a wide area with many independent, very high gain radio 'beams' so to speak. I am basically shooting towards the horizon in all directions, so the beams' "height" only needs to be a few degrees in most cases. The key is getting enough beams to shoot around part or all of the...
  6. blueandwhiteg3

    Parabolic Design Basics for 5.25-5.825 GHz

    I am looking for a few design suggestions for a parabolic-type antenna for use in the 5.25-5.825 GHz range. It will be used for RX and TX purposes. Actually, saying I want design suggestions might not even be right... I'd like some indications as to the concepts and directions I should explore...
  7. blueandwhiteg3

    Ethernet Line Speed & Switches

    Can anybody please confirm... if I have a single gigabit client on a typical gigabit switch with, let's say, 10 fast ethernet (100 mbit) clients, can the gigabit client mostly saturate its link talking back and fourth with the fast ethernet clients? I believe this is the case, but I realized...
  8. blueandwhiteg3

    802.11n and polarization

    802.11n can use multiple spatial streams and OFDM to increase throughput. The specification ranges from 1 to 4 spatial streams. Does anybody have an indication as to the degree of benefit from using a single parabolic-type dish and feeds with varying polarizations in a fixed, point to point...
  9. blueandwhiteg3

    5-6 GHz Rain Fade for Link Design

    Can anybody refer me to a good resource for rain fade / weather-related signal losses in the 5-6 GHz band when doing point-to-point terrestrial links? I have lots of resources for higher microwave bands, but very few for the 5-6 GHz band. I want to look at designing a link in these bands, but I...
  10. blueandwhiteg3

    6 GHz parabolic dish materials

    I'm exploring the idea of putting together my own parabolic dish(es) for special applications where off the shelf is not satisfactory. The transmitter would not put out more than 28 dBm around 6 GHz. I would like some suggestions / ideas / input on the material selection and its response in...
  11. blueandwhiteg3

    Tungsten & Tungsten Carbide Alternatives

    Can anybody suggest alternative metals/alloys with properties in terms of hardness, impact resistance, stiffness, abrasion resistance, etc. in the range of tungsten and tungsten carbide? I'm specifically looking for a metal or alloy here, not a ceramic or composite. Cost is not a major issue...
  12. blueandwhiteg3

    Designing a ceramic metal matrix composite

    I'm trying to put together a ceramic metal matrix composite (prepared using hot isostatic pressing) and I'm a bit new at this, so I'd appreciate some comments. In particular, I would like input on the proposed materials' compatibility, viability, suggested ratios, suggested particle sizes for...
  13. blueandwhiteg3

    Hot Isostatic Pressing Primer?

    Can anybody give me a quick primer on hot isostatic pressing? I have an application where I would like to explore making a part using some kind of a metal-matrix composite / cermet. The objective is extreme hardness (for abrasion resistance) combined with a little more impact tolerance than...
  14. blueandwhiteg3

    Where to find beryllium metal sheet?

    I'm looking for a small sheet of beryllium metal, approximately 1 mm thickness. Size is not too important, 2x2 cm or larger would be suitable. Does anybody have ideas where to find this? I know this is an expensive metal ($1000/kg commodity) but it's also not that dense, so it's not like a...
  15. blueandwhiteg3

    Basic optical modeling software

    Please, be patient with me, this isn't my area of expertise! I'm thinking I need to look at some optical design / modeling software. I would like to model the light transmission properties of various material systems I am experimenting with. For example, I might wish to model the light...
  16. blueandwhiteg3

    Assessing degree of convection under near-vacuum

    I am trying to work out how significant a factor natural convection is under near-vacuum conditions, assuming normal, somewhat moist air. I am looking at using a vacuum for insulation purposes. Essentially, imagine a thick panel (20-100 cm) with a vacuum space inside for insulating purposes...
  17. blueandwhiteg3

    Simple plastics modeling software

    I'm finding that I am working with a few different projects involving plastics, particularly transparent plastics, and need to model their physical parameters. I suppose there might be a bit of glass or metal in there too, but it's mostly about the plastics. The designs aren't so complex that I...
  18. blueandwhiteg3

    Stable, soluble phosphorescent/fluorescent compounds?

    I'm wondering if there are any water-soluble compounds with phosphorescent/fluorescent properties that are stable under light? The objective is to disperse them within an aqueous base. Compounds that are insoluble tend to block other wavelengths of light excessively. Thus soluble compounds are...
  19. blueandwhiteg3

    Highest vacuum readily possible with pumps?

    I am wondering how strong a vacuum I can create using relatively inexpensive (sub $1000) vacuum pumps. I have been shopping around and the best on the market seem to be in the 12-20 micron range. Is there anything much better out there? I've also heard that as you approach the peak vacuum...
  20. blueandwhiteg3

    Impact resistance of boron nitride & other ceramics?

    I'm looking for some information on the impact resistance of boron nitride and other ceramics. I've been looking for data like this online and the data has been at best incomplete. Or comparing different impact values. Can anybody point me to some good data? Or provide a rough outline of how...

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