QUICK SPIDER - No Soldering, No Connector

[Dxista]

@abcd567

That is equal to infinite number of legs.

That was the idea. A solid, angled, ground plane.

@abcd567

Since performance vs number of legs follows law of diminishing returns , not much improvement is expected, but no harm in trying.

Correct, but the point of diminishing returns is not known. I think, based on readings for HF, that 16 radials are close to the limit.

Building a QuickSpider with 16 radials may be a PITA. An existing 8 radials supported aluminum foil umbrella would make a Quickie-Spider 16+.

[SoNic67]

And will add approx 1% to the gain.
That’s how diminishing returns law works - it doesn’t mean it stops working, it just mean that the increase is becoming less and less relevant.

[Dxista]

@SoNic67

And will add approx 1% to the gain.

Over an 8, 16, or the ‘solid’ ground plane?

[SoNic67]

Ah, it was a guess - the 8 to solid ground. All the professional antennas I saw have 4 ground legs. Probably that’s the sweet spot.

[Dxista]

I recently purchased a 6M (50-54 MHz) ground plane antenna. It also has 4 radials only.

The increased number of radials (>4) is usually found in discussions about 1/4 wave vertical antennas mounted at ground level.

[abcd567]

SIMULATION RESULTS

SIMULATION 1 OF 4 - Radiation Pattern, Gain, SWR

Whip & Radials 65 mm

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SIMULATION 2 OF 4 - Frequency vs Gain & SWR

Whip & Radials 65 mm

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SIMULATION 3 OF 4 - Element Length vs Gain & SWR

Frequency = 1090 MHz

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SIMULATION 4 OF 4 - Angle of Tilt of Radials vs Gain & SWR

Whip & Radials 65 mm
Frequency = 1090 MHz

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[wiedehopf]

Can you make the angle of the radials a variable and plot the SWR for 1090 MHz?

[keithma]

Remember to subtract 2.15dB on the gain figures 'cos these plots are dBi which is against an isotropic aerial.

I’ve tried to make one as a reference aerial but the design requires unobtainium and I couldn’t find any

[geckoVN]

@keithma

the design requires unobtainium and I couldn’t find any

Try the guy on ebay who sells 'roundtoits!

[wiedehopf]

@keithma

Remember to subtract 2.15dB on the gain figures 'cos these plots are dBi which is against an isotropic aerial.

Well considering the gain of the FA antenna and quite a few others are given in dBi as well, dBi seems fitting.

[keithma]

I really don’t like dBi, manufacturers use it to make their aerials look better than they actually are. I appreciate it’s a reference point but I just find it misleading.

And don’t start me on aerial makers who claim their dipole has [say] 5dBD gain (over a dipole in free space). That’s another technicality to make an aerial look better. There’s one charlatan in the amateur radio aerial business who claims his dipoles have 7dB gain over a dipole.

But I digress so I’ll get off my soap box now and go and stand in the corner.

Thanks for the plots @abcd567

[abcd567]

@wiedehopf

Can you make the angle of the radials a variable and plot the SWR

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

[abcd567]

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

[wiedehopf]

@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

[abcd567]

@wiedehopf

I’m not sure, did you ever try the wedge approach with the quick spider?

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

Franklin-Spider Antenna (for advanced users)

 

 

[abcd567]

@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.

[abcd567]

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

 

[abcd567]

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

[abcd567]

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

[mikkyo]

Great seeing your design, analysis and functioning protos!

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