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...
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...
I looked more closely into the issues here. The concern of the RF engineers is transmit sidelobes. Some of the two-way satellite services heavily re-use spectrum and they say you can easily interfere if your sidelobes are not well controlled.
Yes, the point of focus is off and probably less effective. I am trying to determine by how much. Actually, more than determine - I can do that mostly by testing - I want to calculate it, or at least numerically estimate it.
These are being tested for more point to point links, with a remote...
VE1BLL: Hahaha... thank you for your sense of humor... and patience...
Higgler: Would 28 dBi work? Perhaps. We have the potential to use a variety of antennas.
Motivations are primarily to minimize the total outward facing area required for transmit and recieve for purposes of reducing total...
Higgler, yes, that is a good way to think about it.
Also, I just realized I didn't include the 1 meter Fortec dish URL:
http://www.fortecstar.com/estore/storefront/default.asp?ProductID=27&CategoryID=8
Given that has an offset angle of 24.42°, I would not expect a huge loss of gain from what...
VE1BLL:
Thank you for the reply. Yes, I understand that the dish effectiveness is not uniform. However, I look at the total dBi gain versus the total area, and calculate the average gain per unit of area. This is a good way to look at size and material cost versus signal performance. It is not...
Can you give me a brief introduction to the math or estimating the losses when working with an offset feed dish as if it were a center-fed dish?
From what I can tell, offset feeding is less effective in terms of dBi gain per cm^2, hence my interest in a traditional parabolic.
Thanks for the reply. Yes, I am aware of the broad issues where the beam focus might not be perfect, etc. and that's OK. I am also aware of hacky uses of reflectors and I'm sure it would more or less work.
My bigger concern is to determine the peak gain I might be able to achieve, specifically...
VE1BLL:
It is rather hard to argue with somebody who claims to be an RF engineer with multiple degrees.
I am going to continue to look into patents and see what I can find. The problem is finding anything in the huge volumes of patents out there.
Moreover, the patents explain the theory, not...
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...
I found an excellent resource:
http://www.wireless-bypass.com/documents/rain%20and%20fog%20in%20the%20UNII%20band-2.pdf
Hope this helps somebody avoid all the searching I had to do. Rain fade data over a wide frequency range is very hard to find online at least.
This is so interesting, I wish I had at least some simple example designs I could reproduce, verify, and then modify.
What kind of materials would be of interest for use around 6 GHz?
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...
