QUICK SPIDER - No Soldering, No Connector

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Added to the post under following heading:
SIMULATION 4 OF 4 - Angle of Tilt of Radials vs Gain & SWR

Effect of inclination of radials on VSWR and Impedance

Please see attached photos. Readings of test equipment (RF Vector Analyzer) are:

  1. Spider with horizontal radials
    Z = 26 Ω
    SWR = 1.9

  2. Spider with slanting radials 45 degrees
    Z = 67 Ω
    SWR = 1.3

  3. Spider with vertical radials
    Z = 73 Ω
    SWR = 2.2

Photo 1 of 3 - Horizontal Radials


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Photo 2 of 3 - Slanting Radials, 45 degrees


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Photo 3 of 3 - Vertical Radials

2 Likes

@abcd567

I’m not sure, did you ever try the wedge approach with the quick spider?
Probably similar to the whip antennas, but might be relevant to have some numbers here :slight_smile:

Did not try the V-Stub, but did try U-Stub 3 years ago.

Franklin-Spider Antenna (for advanced users)

 

 

@wiedehopf

Simulation shows that if the radials of spider are not tilted 45 deg down, but kept HORIZONTAL , the SWR will reduce to 1.5

I have to built it & test it. Cannot totally depend on simulation results.

Vspider-3

I have already tested the V-Stub desing using a mag-mount base on a metallic cookie can lid. It should work if used on QuickSpider with HORIZONTAL radials

The 8 HORIZONTAL radials of QuickSpider will effectively replace magnetic base+cookie can.

Mag Mount Antenna’s Whip Replaced By V-Stub Wire Collinear

 

V-Stub QuickSpider With (1) Slanting and (2) Horizontal Radials

Done detailed Simulation of various combinations of lengths of upper & lower wires for:

  • 45 Degree Slanting Radials (SWR 2.14)
  • Horizontal Radials (SWR 1.47)

NOTE:
Simulation results are yet to be verified by actually building both the above versions of V-Spider, and:

  1. Conducting SWR measurements + tuning (trimming) of upper wire
  2. Putting the tuned (trimmed) antenna to trial run by connecting it to DVB-T >> RPi.

 

(1) 45 Degree Slanting Radials

 

(2) Horizontal Radials

 

LATER ADDITION:

Increasing width of V-Stub’s mouth from 35 mm to 45 mm slightly improves SWR & Gain

V-Spider-Horizontal-Radials-45 mm vee

Ok, I just now finished V-Stun Quick Spider.
SWR = 1.23

Placed about 30cm besides FA antenna & connected to dongle /Pi for 10 minutes. Seems good, much better than standard 1/4 wave spider. Cant say with surety how good, as traffic is very low at this hour.

The white core insulation piece at top, and an extra short piece of wire in it is for sliding up/down to adjust length of upper wire and consequently adjust the SWR.

CLICK ON IMAGE TO SEE LARGER SIZE
CLICK AGAIN TO SEE FULL SIZE

Vspider-built

2 Likes

Great seeing your design, analysis and functioning protos!

Makes me wonder how the model would do with 35-40 degree radials.

The SWR will improve gradually from > 2 to < 1.5 as the tilt is reduced from 45 deg to 0

SWR-vs-Tilt-of-Radials

 

What’s with negative tilt? :slight_smile:

Here you go. Sweep from tilt -70 degrees to +70 degrees.
(-) is tilt UP
(+) is tilt DOWN

SWR-vs-Tilt-of-Radials-2

 

image

Nice chart, based on some work I did years ago, the radial angles affect radiation angles of the reception. Do you have a similar gain chart? or radiation pattern. For those not as familar with antennas, radiation pattern from the side also implies gain pattern. Not much gain is needed at the high angles overhead, and trades that for higher gain primary lobe near the horizon. Nice work on your antenna, I particularly like the sliding top sleeve to adjust the top length.

Cutting was a nuisance. If I cross the sweet point, then I have to solder a piece of wire. Sliding sleeve allows tuning without cutting the wire, and is pretty easy. Once sweet point is found, solder the sliding piece in position. :slight_smile:

 

image

 

 

image

1 Like

Interesting plot. you have about 4db gain with your configuration. The V notch is much easier to control than a coiled wire configuration. Nice and innovative design. Well Done.

1 Like

This is exactly the reason I have gone for V-Stub.

Coil is extremely dimension sensitive, and hence unsuitably for DIY, just like the CoCo is. It is best made using industrial techniques & test instruments. I have tried several coiled antennas, but all failed to perform better than standard 1/4 wavelength Spider, some even performed worst.

The advantage of V-stub design is that you can keep dimensions of lower wire and V-Stub fixed, and just adjust the length of upper wire to tune the antenna to minimum SWR.

1 Like

Has anyone build & tried this DIY antenna?

SWR = 1.23 (measured)
Gain = 3.8~4.3 dBi (calculated by simulation)

Comparison of V-Stub QuickSpider with Bench Mark Antenna (FA Antenna)

FA Antenna >> 30cm RG316 pigtail >> FA light Blue Filter >> FA ProStickPlus (blue) >> OrangePiPC
V-Stub Antenna >> 100cm RG174 pigtail >> Radarbox24 FlightStick (green) >> RPi4

Flightaware 26" Antenna on left side of window
V-Stub Quick Spider on right side of window
Horizontal spacing between antennas = 30 cm

NOTE: The paper behind V-Stub was placed while taking snapshot, as without it the thin wire of V-Stub was not clearly visible in the photo.

 

20200808_212050-SWR

 

08082020_FA_aircraft-8h-r

 

08082020_VStub_aircraft-8h-r

 

08082020_FA_rate-8h-r

 

08082020_VStub_rate-8h-r

 

08082020_FA_range-8h-r

 

08082020_VStub_range-8h-r

 

2 Likes

Did you use this gain to advantage in doing the above comparison?

S

I dont understand what do you mean by “using the gain to advantage” while comparing two antennas. These are compared “as is”.

If you are referring to gain setting of dongles, then both dongles were set at gain 48.0