*Short update at bottom of page
OK, now that we have the poorly written Buzzfeed headline out of the way, here are the results of my first Vivaldi antenna build.
I only tested it for a few minutes indoors and out, and the initial results have me pretty excited to experiment some more. I was able to receive and decode L-Band AERO signals on my AirSpy Mini without an LNA outdoors. Indoors, through a wall, I was able to view the signals but not a high enough SNR to decode. Pretty impressive without an LNA.
Tomorrow I'll try the N3 SDR and a couple RTLSDRs out and also with an LNA and filter in the mix too which are sure to help things out. Might even get as far as putting the downconverter in line and see what I can get in S-Band and beyond. I'll report back in case there are any lost souls interested in my scratchings on these cave walls.
Anyway, Here's a pic of the antenna. Nothing fancy. Just Scissor Cut PCB, wired up with some tiny semi-rigid coax.
After unexpectedly hitting RTL-SDR.com's site I've received a few email question on the dimensions of this particular antenna. It is the 2nd one pictured in the previous blog post with the outer copper cut down to look like this. I'll post the image here so you can print and cut or toner transfer for yourself. There is nothing special here. I made this design in PAINT with elipticals. More below.
As to answer what I've been able to receive well on this so far I've copied ADS-B – Really gets the gain up there over the other antennas I've used, Inmarsat Aero, and some irridium sats among others. I've not put the LNA in line just yet as both of mine seem to be screwing up. Not sure if I'm not getting voltage out of the AirSpy Mini or if the LNAs got fried somehow all of a sudden (more likely – sht happens ¯\_(ツ)_/¯ ).
In any case, I have some fresh LNA boards sitting here and will populate them today with BFP420's. (have a bunch of them) I hope to have an update for you all tonight sometime. It's been busy here, last *ahem* working day of the year and all. With an LNA in line I expect this to perform pretty damn well.
Need scissor cut PCB? Found some 5×8 on ebay here: http://www.ebay.com/itm/Scissor-Cut-Flexible-Printed-Circuit-Board-Material-Copper-Clad-5-X-8/201285628477 – no affiliate links here folks. Mine is 7×10 but you can see I cut it back a bit. The 5×8 should work nicely, worst case scenario you lose a tiny bit of bandwidth at the bottom end.
More to come. If you have questions please use the comment form below, twitter @kd0cq, or email me. chris [at] kd0cq dot com. Follow me on twitter to join in on all my misadventures in radio @kd0cq.
73's for now.
Hi, regarding your airspy problem check the bias t inductor in the airspy. Mine was not soldered and gave intermittent connection – see picture.
Mine turned out to be a blown protection diode in my L-band LNA and the others needed more power.
Very good article about this type of antenna,could you explain how the coax is solderd on to the pcb
I just soldered the center conductor near the rear edge to the top section and grounded to the same area of the lower section.
Does it matter what the thickness of the antenna material is?
What would the minimum size dimensions be to cover 1.090 Ghz onwards?
Could an N connector be mounted near the feed?
Made one of these a while back and mounted it in a WOK dish lid – isolated
(Chinese cooking food dish lid).
Also put two side panels at 45`deg each from the Antenna on the Wok,
And gained a further One S point 6db.
The short coaxial connection for the Vivaldi was cut to quarter wave length
for mid band at 1500mhz, This also helped lower and widen the SWR even more
over a larger range.Can post or send pics if anyone is interested….cheers Tony.
Nice work Chris !
Hi Tony, would like to see the Vivaldi with the wok reflector, must be a thing of beauty.
Is this on 1 sided or two sided PCB material? If two how are they connected? Or left floating?