Anyone know of an easy to use Horn Antenna calculator? - Page 1
Forum section: electronics / rf-microwave

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: April 12, 2017, 07:33:10 pm
content: Im interested in building big horn antennas like the seti horn of plenti and smaller horns to test as dish feeds. I would like to build them in the L and S band. I see lots of DIY projects using horns in the X band etc, but I just can't seem to find much information on building them. What im really looking for is an easy calculator like this one for helix'eshttp://www.daycounter.com/Calculators/Helical-Antenna-Design-Calculator.phtmlor this one I use for patcheshttps://www.pasternack.com/t-calculator-microstrip-ant.aspxAre my google skills that bad or are there just no calculators out there for horns? Im really interested in seeing weather small arrays of larger horns can be lighter and more convenient than a dish while getting around the same performance as a 3M or so dish.I have a 3M dish that I just cant set up right now. It seems to me horns can be moved and stored easier along with being light enough that building or buying an AZ/EL system can be pretty cheap. Ive been trying to work with Helix antennas but for some reason they have awfull back to front rejection and I have to twist the helix around the X axis to find the point were it get a "decent" vwsr. Im sure I just need to put more effort in to the whole helix thing but im thinking in the end a Horn is probably going to get the best back to front and no lob spill over to hit the ground and add temperature to the NF. I.E besides a dish a horn is probably the best possible antenna for very weak signal work? Interests being Astronomy, SatCom, Deep Space Network, and maybe even SETI.

author: metrologist
author_rank: Super Contributor
timestamp: April 12, 2017, 07:42:16 pm
content: I'm sure my google fu sucks as bad as yours...http://www.rfwireless-world.com/calculators/Horn-Antenna-Calculator.htmlhttp://www.dxzone.com/dx27031/horn-antenna-designer.htmlhttp://antennadesigner.org/horn_downloads.html

author: LaserSteve
author_rank: Super Contributor
timestamp: April 12, 2017, 09:19:03 pm
content: Not exactly a calculator, but there is speadsheet or two hidden in here:http://www.w1ghz.org/antbook/contents.htmSteve

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: April 13, 2017, 12:41:32 am
content: Thanks a lot. Those are exactly what I was looking for, not sure why I couldn't find that stuff...Can anyone tell me if helix antennas are pretty finicky or if its just my build? My SWR curve was pretty broadband as predicted but after twisting the antenna around to find the perfect spot, at 1454mhz (which is what I wrapped it for) I got at best 6 to 8db return loss, and when I walked around the thing holding a microwave synth tuned at 1.454 the peak signal received never lost any power weather I was standing in front of the antenna or behind the ground plane. I have a feeling my return loss could be improved, but the antenna was not as directional as I anticipated.Also out of curiosity if you build a broad band antenna like a Horn or a Helix but you are only really wanting to use it on a small portion of the spectrum will building a matching network before the feed line give boosted improvement? I would guess obviously yes but I dont see any other projects doing this, it doesn't seem to be common to add a matching network on frequincies over HF, with the exception of micro strip antennas etched on a pcb.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: April 13, 2017, 06:24:27 pm
content: Well here is my front end for L/S band week signals,Antenna ->PSA4-5043+ LNA, +20db wide band, NF less than 1db -> Band pass filter, usually made or chosen (if bought) to be as narrow as possible for the application ->PSA4-5043+ LNA-> +30db LNA made from removing filter and patch from an active GPS -> Downconverter if S band -> Airspy Mini SDRI put the two wide band mini circuits LNA's in the front because they should bring down the whole receivers NF, and I would assume having a wide band LNA in front of the band pass filter instead of a more narrow band one there would help prevent any IMD. Im either using the receiver right at the antenna and sending over ubiquity radios or running LMR600 feed line.At this point it all really comes down to the antenna performance, im sure the receiver could be better too but for now an AirSpy is good enough. I don't know how to use EM modeling software and I have so much going on its not really something on my short list to learn. Basically I just need to figure out the quietest antenna which allows for modest gain (as you can always add another to get more gain). I was really thinking a helix style would be it but ive had a harder time with them than I figured, maybe adding a quarter wave brim/shield around the ground plane would help improve some performance issues. Ive also been wrapping them around ABS pipe so im not sure what the dialectic constant of ABS is but that could be why the ones I see with more of an "air core" preform better?Ive looked in to yagis too, but having to build more than one long boom circular polarized yagi just does not sound fun at all, and im not sure how much better a long boom yagi would be compared to a perfectly built helix anyway. I started with batch antennas but there gain pattern isn't all that great if you want to keep ground temperature out of the mix. So I guess the question is, is a few moderately sized horns going to be the best antenna solution, or are properly built helix antennas just as good?

author: pgo84
author_rank: Newbie
timestamp: May 11, 2017, 06:09:46 am
content: If you want to have an idea about the radiation patterns of your horn antennas, you can try this online calculator:http://hornantennacalculator.blogspot.com/