Handy SPIDER - No Soldering, No Connector

[ab cd]

Handy SPIDER - No Soldering Required, No SO239 Connector Required

Maximum Range Curve By VRS

Hardware Used for Range Curve Plotting:
Handy Spider >> 12 ft / 4 m RG6 Coax >> Generic DVB-T (black) >> Orange Pi PC

Trial Run - Indoor Near Large Window

HOW TO MAKE

Please see these posts also for previous Versions:

(1) May 2015

(2) September 2016




STEP 1 - Stuff Required

STEP 2 - Cut Coax Into Required Pieces

STEP 3 - Remove braid & Insulation

STEP 4 - Bend Wires

STEP 5 - Assemble Radials

STEP 6 - Bend Down Radials 45 Degrees

.

 

[ab cd]

ENHANCEMENT FOR OUTDOOR USE

1) Apply a rapid setting (5 minutes) sealant like 2-part epoxy, or silicone, or hot melt glue, or similar at the point where radials enter the outer jacket of coax.

2) After installation. wrap the F-connector in tape to prevent moisture ingress. You may also use outdoor type F connector which are water resistant

 

[ab cd]

Testing of Quick Spider by Antenna Analyzer

VSWR=1.2, R=59Ω, X=5Ω, and S11=-20 @1090 MHz

Plot of VSWR vs Frequency 137.5 Mhz ~ 2700 MHz.
Marker at 1090 MHz, minimum SWR at marker

 

[AnirbanSen]

If I don't have a VNA, is there any way I can find out the sweet spot in a coax?

 

[ab cd]

If I don't have a VNA, is there any way I can find out the sweet spot in a coax?

If there is a way without VNA, it is trial and error. Start with a longer than calculated length, then keep trimming little bit at a time to improve performance, till performance starts to drop instead of improving. Stop there and go back a step or two.

 

[AnirbanSen]

What are the tell-tale signs from looking at @weidehopf's graphs1090 program?
SNR? ADS-B rate?

 

[ab cd]

What are the tell-tale signs from looking at @weidehopf's graphs1090 program?
SNR? ADS-B rate?

"ADS-B Message Rate" is the prime graph to consider. SNR comes next.

On "ADS-B Message Rate" graph if, "Messages > - 3 dBFS":
- Is less than 5%, no need to reduce gain.
- Is more than 5%, reduce the gain in steps of say 2 or 3 dB, then wait for an hour or more, then check "Messages > - 3 dBFS" on the "last hour" graph

.

LAST HOUR GRAPH

 

[AnirbanSen]

"ADS-B Message Rate" is the prime graph to consider. SNR comes next.

On "ADS-B Message Rate" graph if, "Messages > - 3 dBFS":
- Is less than 5%, no need to reduce gain.
- Is more than 5%, reduce the gain in steps of say 2 or 3 dB, then wait for an hour or more, then check "Messages > - 3 dBFS" on the "last hour" graph

This is my current. Coax spider. Radials somewhat mangled due to a hate crime.

Will be testing a similar thing on the roof, a SO239 4-legged spider (the other 4 legs - soldering did not stick despite several attempts) and also a PCB 3dbi gain antenna. There's also a bandpass filter. The LNA materials have still not arrived.

 

[AnirbanSen]

ENHANCEMENT FOR OUTDOOR USE

1) Apply a rapid setting (5 minutes) sealant like 2-part epoxy, or silicone, or hot melt glue, or similar at the point where radials enter the outer jacket of coax.

2) After installation. wrap the F-connector in tape to prevent moisture ingress. You may also use outdoor type F connector which are water resistant

View attachment 2581

If the radial wires were insulated, i.e. a single core 18SWG copper electrical wire was used and the insulation removed upto only 2.1mm (which goes into the coax), how would it affect the antenna functioning? Does ground plane require the wires to be insulated?

Would a ferrite bead help in using a handy spider? Where should it be placed?

 

[AnirbanSen]

The silicone paste makes a blob so that water flows from the center to the edges.
Its about 3-4mm in height. Would it affect the performance of the antenna at 1090MHz?

The core wire is 64mm from coax end till tip. (Now 3-4mm being covered in paste)

 

[ab cd]

View attachment 2915
The silicone paste makes a blob so that water flows from the center to the edges.
Its about 3-4mm in height. Would it affect the performance of the antenna at 1090MHz?

The core wire is 64mm from coax end till tip. (Now 3-4mm being covered in paste)

Covering whip with insulation (paste) does not make any difference in performance, particularly if insulation covers only on a small part of the whip.

.

 

[AnirbanSen]

Increase in messageswith the rooftop antenna and 20dB amplifier.

Increase in aircraft distance

Message rate. Note that Messages > -3dBFS is 1.4% in the last 24 hours. dump1090-fa gain is set to AGC (-10).

Thanks for the stellar designs and advice. Much appreciated.

 

[foxhunter]

I will try to build this DIY antenna over the weekend.
Is this a regular SAT cable? Anything special to be considered?

 

[foxhunter]

Today it is a rainy day, and i decided to build my own first DIY spider based on this tutorial.

Looks more like made by a three year old kid, but i wanted to do some testing first.
And yes, it's an improvement straight away.

This was the point i changed the connection of the antenna to the DIY one:

And the spider itself.... stop laughing!!!

 

[ab cd]

You built 4 radial version and got some improvement.
Build 8 radial version, you will get more improvement.

 

[foxhunter]

I know, but i wanted to test it first.

Next step is visiting a tool store for getting the required stuff.

 

[AnirbanSen]

"ADS-B Message Rate" is the prime graph to consider. SNR comes next.

On "ADS-B Message Rate" graph if, "Messages > - 3 dBFS":
- Is less than 5%, no need to reduce gain.
- Is more than 5%, reduce the gain in steps of say 2 or 3 dB, then wait for an hour or more, then check "Messages > - 3 dBFS" on the "last hour" graph

View attachment 2854


.

LAST HOUR GRAPH
View attachment 2855

My > -3dBFS was showing around 11-15% on AGC. When I set gain to 48, it became less than 1%
At the same time, my ADS-B signal level dropped from -8/-10dB to ~ -18dB.

What does this mean?

 

[wiedehopf]

It means use a gain of 49.6?

Maybe you might want to read this: https://discussions.flightaware.com/t/thoughts-on-optimizing-gain/44482

 

[AnirbanSen]

I am about 10Km away from a busy airport. I would prefer longer range over quality of nearby flights.
That said,
at +49.6 gain, strong signals are about 1.2%. At AGC, strong signals are 23%+.

 

[wiedehopf]

AGC is equivalent to a gain of around 55, so it's quite a jump.

Test both 49.6 and AGC and see if AGC gets you extra range (it might not).
If it doesn't get you extra range might as well have better close in reception.