QUICK SPIDER - No Soldering, No Connector


#1

DIY QUICK SPIDER - No Soldering Required, No SO239 Connector Required

Maximum Range Curve By VRS
HARDWARE: Quick 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

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#2

Now, that one is very well made!


#3

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


Location Really Matters ! Try another
#4

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


#5

@ABCD: What does that mean? In comparison, say to the FA antenna. In simple terms! Thank you!


#6

Based on this test alone, I cannot compare antennas.
The instrument I have used measures only VSWR/Reflection/Impedance (R, X).
This instrument does NOT measure the following parameters necessary for comparison.

  1. Antenna Gain
  2. Antenna Directivity/Radiation pattern
  3. Suppression of common mode/unbalanced currents

Ok, then what is the purpose of this instrument/test?
The purpose of this instrument is to tune the antenna.

It checks:

(1) At what frequency antenna is tuned:
The tuned frequency is where the VSWR vs Frequency curve is at minimum.
If it is tuned at lower than design frequency, reduce whip’s length by trimming the whip.
If it is tuned at higher frequency, increase whip’s length by soldering a small piece of wire at top of whip.

(2) How much is VSWR:
If measured VSWR is greater than 1.5, than impedance matching devices should be used.
If the VSWR is 1.5 or less, the antenna will perform good without any impedance matching device.

In case of Spider, some amount of reduction in VSWR can be achieved by adjusting the angle to which the radials are bent-down.

Horizontal radials, Impedance is 32 ohms
Slanting radials 45 degree, Impedance is 50 ohms
Vertical radials (=dipole), Impedance is 75 ohm


#7

Practical demostration of how the inclination of radials affects VSWR and Impedance

Please see attached photos. Readings are:
(1) Spider with horizontal radials, z=26, swr=1.9
(2) Spider with slanting radials 45 degrees, z=67, swr=1.3
(3) Spider with vertical radials, z=73, swr=2.2

CLICK ON THUMBNAILS TO SEE LARGE PICTURES

https://c1.staticflickr.com/1/446/32501334462_b814ba037c_n.jpg . https://c1.staticflickr.com/1/405/32654383295_a06f14e4a4_n.jpg . https://c1.staticflickr.com/1/313/31811480314_35dc93800a_n.jpg


#8

Thought I would share my results of the “QUICK SPIDER” vs. a cantenna. The only thing I changed was replacing the cantenna with the quick spider. The rest of the lineup (~40ft RG6 coax into a Nooelec2+ dongle into a Pi3 with a stock PiAware 3.5.3 install on Stretch). Happy to report that I am getting more planes and postitions reported, so this might be my next incremental change for my second site that has the blue FlightAware ProPus stick. Love seeing more of the planes and positions appear here in fly-over country.

A picture of the spider and cantenna (looking east) if any interest is below. The cantenna is 67mm across and 69mm tall (used to be a can of mushrooms :wink: ) The spider was built to abcd567’s specs in this discussion. Some might say the difference might be because the spider is 10 inches higher than the cantenna. Will think about that one… YOUR mileage may vary…


#9

A brief update on my adventure with antennas and such. I substituted the FA ProPlus stick for the Nooelec2+ dongle, with the same spider antenna, same location, and saw a dramatic improvement in # of aircraft and positions. I suppose this is to be expected as I have a 300ft cell tower staring me in the face to the east, so the filtering helped plenty. Oddly enough, putting a FA filter in line withe the Nooelec2+ dongle made things worse :frowning:

Next, I mounted the spider antenna up on my chimney, to make the reception horizon as unrestricted as I can with the trees and hills around me, FA ProStick Plus dongle. I think I am at the point of diminishing returns, happily - positions and aircraft consistently highest I have ever seen, and my range seems to very closely match my heywhatsthat prediction.

I’m pretty happy with being able to experiment with the no/low-cost antenna recommendations by many, especially the excellent write-ups and testing from @abcd567

I have gone from an average of ~200 planes/10K positions/day, to ~700 planes/90K positions/day and much further out since I started this fiddling.

Here’s a polar map after several days’ running with the new configuration.


and the theoretical plot from heywhatsthat.com (10000 and 30000ft elevations)


Can't get range more than 80 km!
#10

For what it is worth, this is an update to my antenna experiments.

I applied for and was granted a FlightFeeder Orange kit. My goal was to compare the homemade kit (FlightAware Pro-Plus, home-terminated RG6 75 ohm cable, home-made spider antenna) with the FlightFeeder Orange kit (good profesionally-terminated 50 ohm cable, FlightAware antenna, FlightAware dongle, FlightAware filter). The FlightAware antenna is located on my (unused) chimney at the same elevation as the spider about 1 foot to the west and 1.5 feet to the north. The picture below is looking directly to the east. There’s a cell tower roughly 1 mile away, and the regional cable/communications provider’s central office for our town just below our home (the antenna/dish farm).

The cable lengths from the antennae are nearly the same and terminate to a Pi and the FA orange box in the basement. Both gains are currently set to ‘auto’.

I may have had unrealistic expectations that a professional kit would perform better than my home-made stuff. I have been surprised to find the home-made kit consistently gets me more plane and position counts farther out than the FlightFeeder Orange. Not by much, but enough to be significant in all directions during any observation period. So now my interest is renewed into finding WHY that is. I am not likely to move the FA antenna more east to the spider any time soon (aversion to climbing on rooftops). I stand on the shoulders of the folks who have tried different things and shared their experiences here (THANK YOU), and will start with gain adjustments on the Orange, keeping the Pi-Spider setup constant, to see what happens.

This is the sort of thing that keeps my interest in this hobby, especially when I happen to catch balloons from Project Loon floating by in the ‘vicinity’ :slight_smile:

P.S. The FlightFeeder kit that the FlightAware folks put together is top-notch, in my opinion - it’s about as painless and ‘plug-and-play’ as it can get - kudos for a job very well done.


#11

Knowing what I known now, and taking into account where my RPi and antenna are installed - in the garage - the best bang for the buck is still an $8 no-name generic dongle, and a QuickSpider antenna.

Other installations and locales may benefit from pre-amps, filters, high gain antennas, etc., but not necessarily.