best antenna

[abcd567]

Scroggie:
Software & calculations provide a starting point only.
Finally it is trial and error, trimming and adjusting the built prototype.
I built one based on calculation then startted trimming, it improved, then after a point worsened.
The wire was cut smaller than the length where I got better results.
I had to make another prototype with longer wire, and started trimming testing, but this time I was aware not to cut too much.
DIY antennas are "trial and error" and "a shot in dark". Happy experimenting and good luck.

[Scroggie]

abcd567:
My previous post has gone "unapproved" for some reason but I think it will appear eventually.
In addition to that though I've been Googling coil calculators and found a very good one called Coil64-1.1.7 (Google it - I'm not sure if links are allowed in these posts)
Anyway, using that software and your wire / dimensions it gives your coil a value of 0.212 microH and mine 0.232 microH. Reducing mine to 15 turns and I get something close to your value.
Another option using my wire would be 10 turns closely wound (it is enamel coated) What do you think of that idea? - I think it would be more rigid and a little easier to make.

Scroggie

[Scroggie]

abcd567:
I had a go yesterday with some 1.5 mm copper wire (I don't have any steel and anyway I wanted to solder it to an F connector)
Because my wire was so much thicker than yours I have ended up with an outer diameter of 8.4 mm - the drill I wound it on was 5,1 mm
At first I mounted it in a north facing window and was a little disappointed until I looked at the same direction on my other outdoor antenna/receiver which showed very little traffic to the north of me anyway.
Today I moved it to a south-east facing bedroom window and now it looks very promising. and this is with a coil of a different diameter! The other dimensions are the same.
Now is not the time to get a very sensible comparison given that the daily count of aircraft I'm seeing has dropped from 2500 to 400 but considering the difference between the ranges from an 8 element coaxial colinear at 40 feet and your design in a bedroom window I'd say it's very successful. To only see 22 aircraft at what is normally peak time here is truly remarkable.
Now I need to make another one, weatherproofed and mountable on my ham radio mast!


Scroggie

[abcd567]

Scroggie:
I wound the coil on 3/16 inch dia drill bit which is 4.76 mm dia (I do not have mm size bits).
The wire used is thin steel tie wire, diameter aprox 0.5 mm (see the wire on floor in first photo below).
I used thin wire as I found it easier to shape, and easier to wound on stud of magnetic base.

Initially I made length of upper wire more than 137mm and after making, measured SWR by VNA. It was 2.1
I then bend the tip of wire to reduce length and measured again, and repeated this till I got reading of about 1.57

Optimized Whip Steel Tie Wire-R.jpg



Coiled Collinear and Quarter Wave-2.jpg

[Scroggie]

[QUOTE=abcd567;n184155][B]Wire Collinear with Coil & Ground Plane


(1) SIMULATION: Lower Radiator = 60mm, Upper Radiator = 137mm

SWR = 1.69
Gain = 4.98

Coiled Whip - 60mm lower- Radials 45 degree down.png



That looks really good - I'm going to make one.
My colinears have been very successful but I have no way to do the detailed analysis of them that you clearly do so this would be an excellent antenna to do comparisons with.
Just one question if I could. Your coil diameter is 5 mm - hopefully that's the internal measurement, ie was it wound on a 5 mm rod / drill bit?. I was planning using 1.67 mm diameter copper from the inner of some co-ax I have so if it's the outer diameter it would need to be wound on a 1.66 mm drill which wouldn't be practical.

Scroggie

[petercr]

2 here on a Saturday morning when there would usually be 25-30
4th April Virtual Radar Capture.PNG

[Scroggie]

This is at a time when pre-coronavirus there would normally be 150 - 170 aircraft in range!

[petercr]

My plane count is down to about 1/3 of what it normally is but with cargo still flying between China and New Zealand, I'm still seeing close to my normal Max range...

[abcd567]

Wire Collinear with Coil & Ground Plane


(1) SIMULATION: Lower Radiator = 60mm, Upper Radiator = 137mm

SWR = 1.69
Gain = 4.98

Coiled Whip - 60mm lower- Radials 45 degree down.png


(2) SWEEP- lower radiator length vs SWR

Coiled whip - Lower wire length vs SWR.png



(3) SWEEP- lower radiator length vs Gain

Coiled whip - Lower wire length vs Gain.png

[abcd567]

Wire Collinear With Coil & Mag-mount Ground Plane.

Note: Because of extremely reduced number of flights due to covid19 epidemic, the difference between two whips is not glaring in the graphs. I will re-test after flights are normalized.

Coiled Collinear and Quarter Wave.jpg

.

Coiled Collinear - SWR - R.jpg
.


coiled whip - aircraft-R.png

.

coiled whip - range-R.png

[wiedehopf]

utack:
It depends on what your obstacles are.
ADS-B/1090 MHz is line of sight, so you need a clear line to the aircraft you want to receive (clouds don't count, trees significantly reduce range in that direction)
https://forum.flightradar24.com/foru...-get#post89878

[petercr]

Kind of antenna related - got up on the roof this morning and replaced 3x 5m sections of what looked like RG196 coax (with a 15cm N-SMA stub) with 1x 15m length of pre-terminated LMU400 coax and my range is now in excess of 220Nm to the N / NE plus about 20% better than previous to the E & S / SE.

[utack]

I have received the jetvision antenna, and at a indoor window I have gotten many more messages, but the range only increased slightly (maybe 20nm) over the small indoor antenna
Is this all due to my heavy interference with mobile, and the filter will fix it, or do I have to move the antenna outside to really see the benefits?
FWIW the "strong messages" method gives me 0.1% with agc

[wiedehopf]

Consider upgrading to an blue FA prostick+ or green AirNav Flightstick as well.
Independent of the antenna, those will improve reception.

A spider antenna on the roof with some RG6 or other quality coax that isn't too long, combined with a filtered / amplified receiver should give you 200 nmi of range if the surrounding terrain or houses don't block your view of the horizon.

In short: the spider antenna outside with clear view and proper coax will outperform any antenna that is indoors.
But if you are limited to having an antenna indoors, the FA antenna is one of the best antennas for that purpose.
(just realize that you reception is limited when the antenna is indoors)

[petercr]

+1 for the FA antenna. Home-made is good for starting out or if $ are tight.