FEED for parabola
do you know about some book, which is the best about parabolic antenna ? Exactly about feed. I know basic theory about it, but I need some type of feed, about parameters etc. Or some picture feed. I need find the best feed and I need some inspiration. The antenna must have good gain and good spillover (class 2 or rather 3). The class is problem, I have dish with high f/D (>0.3) and without rim.
Thank
There are numerous references. Try Kraus and Silver as a starting point. Balanas, Lo, Jasik (and the following editions) are also good references. Transactions on Antennas (IEEE) will have plenty to look through. .
Thank,
but I need some practical design, rather. My target is find feed with ideal radiation pattern = it is good gain and good spillover of parabolic antenna. I know absolutly ideal theoretical radiation pattern of feed - it is in attachment, but how can I do it ? - it is not possible :) But I try find very similar result.
By "practical" I take it that you want a pre-made solution. Contact Andrew or Seavy for numerous off-the-shelf solutions. Hardly any thinking or design work will be needed. Only cash is required.
Thank,
i need only inspiration, so what kind feeds are possible, for example: hat feed, horn feed, loop antenna as feed and so on, do you understand me ? I need inspiration what form is good.
I'am working on a Horn feed for a parabolic reflector. It's going to be a conical horn which is in turn fed by a circular waveguide.
Hi, I am not sure, if I understand exactly, can show me picture ? Thank
"Antenna Theory and Design" by Stutzman and Thiele, Chapter 7, Section 7 has a good discussion about feed antennas for reflectors, and many references.
Is your antenna a parabolic dish with circular aperture, or a parabolic cylinder? For a parabolic dish, you have a very small f/D of 0.21 (a very deep dish), and you seem to want a feed with an inverse taper to generate an almost uniform aperture illumination. Is this correct? Do you have a very special application in mind? The high illumination of the reflector edge will have a significant effect on the antenna performance for many applications (high spillover; high sidelobes...)
The usual practise is to taper the feed so that the illumination at the edge of the dish is reduced by 10dB or so. This typically gives a reasonable compromise between efficiency and spillover. A popular choice from earlier days is to use a dish with f/D around 0.41 - 0.44, where you find that a simple open-ended circular waveguide of diameter around 1 wavelength gives quite a usable feed.
Thank, I have this book, but about the earlier edition, try me name of chapter.
Yes, it is parabolic dish with circulat aperture. f/D < 0.21 is problem where is D > cca 1 m :(, there is about >0.36. Expressly I have problem with class of antenna, i.e. spillover and sidelobe. The "10 dB edge" is high, I need about 20 dB reduced. Open-ended circular is good, but in the E - plane have very high sidelobe, and this cause spillover of parabolic antenna. Circular waveguide have problem, that the field is not uniform. A tried dual mode feedhorns, it is OK, but very frequency-dependent :(
Added after 3 hours 16 minutes:
I am trying find book:
Microwave Horns and Feeds by A. David Olver, Institution of Electrical Engineers, Peter Clarricoats
have it somebody please ? Thank !
I have the 2nd edition of Stuzman & Thiele. The Chapter is titled "Aperture Antennas" and the Section is "Feed Antennas for Reflectors".
Your problem sounds non-standard, and I doubt that the solution wll be in a book of this type.
It seems you are trying to under-illuminate the reflector quite strongly. If a Potter-type horn is too narrow band, have you looked at a corrugated feed horn? There are some overview-type articles on this type of feed by Granet & James.
I dont know, what I edition have, because I have not first page :) - but i think, that is 1st edition, because this chapture is not here.
Yes, of course, the Potter-type is good, but only for one frequency, it is very frequency-dependent, exactly for 10.3-10.65 GHz is it possible, but for 10.7-11.7 GHz is useless. Corrugated feed horn - I am experimenting with it at now.
W1GHZ 10 GHz online Antenna book