I’ll take a photo when I get home. Maybe I’ll also do a comparison, since they are not permanently connected to each other. I recall an improvement that was noticeable, but I didn’t quantify how much.
First picture was 0.4 second at ISO 6400 using existing light, so I took another with a flashlight. It’s essentially the same as this one.
@ExCalbr:
We cannot see the photo, it says “content protected by the owner”.
The photo from Amazon is reflector lamp shown below. In what manner it is placed over the Spider?
We cannot see the photo, it says “content protected by the owner”.
Can you see the pictures now? Right now it’s simply resting on top of the spider. The antenna is held up by a plastic clothes pin.
A 75mm x 71mm turned out to be a slightly better ground plane.
Built a dipole antenna and the overall coverage is better than a 1/4 whip antenna.
http://img03.imgland.net/afOwg1d.jpg
http://img.imgland.net/0aDMLOq.jpg
Coverage with 1/4 whip.
http://img04.imgland.net/N9WIkMr.png
Dipole 150+69+6+69+150.Open ended.
http://img03.imgland.net/_REA7NJ.png
Same Dipole with a closed end.
http://img.imgland.net/Ej89WG4.png
Feed line is 50 ohm.So will this formula work,to optimize impedance.
I’m looking for a sub NZ$50 antenna for AirSpy mini.I have narrowed down to a few options;
5/8 3dBd Antenna
http://img04.imgland.net/tzqPkyr.png
5dBd Collinear Antenna
http://img03.imgland.net/jJ9_9uR.png
from eBay from user stanislavpalo130
7dBd whip antenna from Aircraft Tracking Avionics which looks like BS-1105 with magnetic a base.
http://www.tmrf.co.uk/wp-content/uploads/76_bs1105.jpg
Can anyone recommend which antenna will work better indoors?
Cheers!
@hsran
I have not used any of these, so cannot say. Cannot depend on manufacturer’s or seller’s claims alone.
Member TomMuc has tried and compared many similar antennas, PM him and ask.
This dipole has a impedance matching stub and requires adjustment of cable tap position by trial & error or by test equipment. It therefore deviates from the very essence of this thread which is “Easy Antennas for Beginners” and is for antennas which do not require any painstaking adjustment/tuning.
Feed line is 50 ohm.So will this formula work,to optimize impedance.
Yes, if in the formula you use ZFDR = 50.
With lamp shade placed as shown in your photo, the conical metallic lamp shade is the groundplane, and not the 4 radials.
You should therefore rename it from “Spider” to “Cone-tenna” 
However your cone is too big, more than 1/2 wavelength. Normally groundplanes are 1/4 wavelength. How does your Cone-tenna perform compared to Spider?
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hi
i use 5dBd Collinear Antenna buy on eBay
ebay.fr/itm/Antenna-ads-b-co … 1755304051
It s a very good antenna
you can see my stat
Thanks @LFBDBORDEAUX!
The best indoor antenna so far with great coverage.
(1) Is the connector SMA panel mount / bulkhead?
(2) vertical radials (75 ohms) is also a successful configuration, but popular amongst hams is 45 degree slanting (50 ohms). The reason is ham equipment’s defacto standard is 50 ohms. However TV & Satellite’s defacto standard is 75 ohms.
This is an aerial I whipped up with 1/2 wave dipole sitting roughly 1/4 wavelength of the reflector and 6 metres of cable. I don’t know how it compares with others but It is the best so far, however, I had one with a solid reflector behind it and it increased aircraft seen and positions. It was heavy and not appropriate for the wind at the time. The antenna is pointing due East. The other thing is it may have been a busier time. I can pick up an aircraft in the capture area about 60 nautical miles at 2000’ and aircraft over Melbourne at approximately 11,000’. Anyway here it is:
I overlayed the PlaneFinder graph on the Southern Australia Map to give you an idea (photo shop job.) The green ring was supposed to represent 250 nautical miles but it is a bit skew whiff! You will notice there is a position line to the south west. That is QF64 from South Africa coming through to Sydney. There is not much traffic through that area but it serves to demonstrate signal coming from the rear of the antenna.
You will notice a bare area of positions to the northeast of the overlay. That is due to a building and tall cypress trees located west north west through to a North North East. The photo link below is 180° so looking at the aerial is due West (in the photo,) building North and aerial direction is pointing due East between the tree and the house.
i692.photobucket.com/albums/vv28 … /nORTH.jpg
Not so obstructed but the house roof is in the direction of Tasmania where I received my best position from.
i692.photobucket.com/albums/vv28 … 20copy.jpg
I bought a prostick with filter and the results were telling as indicated in red. Ignore the numbers, I have had outages on the pi and chopped and changed aerials which upsets thing a little.
This is my best range i have noticed so far.
Do you have any suggestions to improve antenna??
Looks great!
Is “1/2 wavelength” the length from tip to tip of dipole, or the length from any one tip to center (where cable is connected)?
A couple of weeks ago I started with a Standard-DVB-Stick with the delivered antenna. RasPi2+Stick+antenna all indoor at the window. I changed the small antenna and installed an old F-16 aircraft blade antenna (Type CNI 22-3A) instead. This increases range and number of a/c. Then I read how to build a small ‘Spider’ Ground Plane; that increases range and number of a/c again.
My DIY-“SPIDER”:
For outdoor installation I bought via ebay a 5/8 antenna, like hsran is asking for and offerd here
http://www.ebay.de/itm/Antenna-5-8-great-coverage-ads-b-flightradar-24-1090mhz-high-gain-BNC-con-/301963132273?hash=item464e67bd71:g:zYAAAOSwwbdWNzS1
The results are very similar to the DIY-Spider, but it’s well protected against bad weather conditions.
The 5/8 antenna is mounted on our balcony, 5 m above the ground. There are some houses close around, but it’s OK.
Maximum range is > 350 km at FL 380. Since I’m receiving with my outdoor antenna, I get approx. four times more reports and number of a/c is more than twice as indoor
My 5/8 antenna:
https://image.ibb.co/h0HcQv/160530_my_ADS_B_5_8_antenna.jpg
See my statistics:
https://image.ibb.co/kW08Xa/160601_statistics.jpg
I would recommend the 5/8 antenna from Stanislav Palo, it’s cheap in price, well made and nearly ready to be installed. You have only to fix/screw on the radials and connect the antenna cable and run your equipment …
I use the Flightaware Pro Stick with the FA Bandpass Filter, this works much better than the ‘standard’ DVB-T-stick.
For the moment, my RasPi2, FA Pro Stick + FA Bandpass filter are installed in PET bottle very close to the antenna 
RasPi2 works with a EDIMAX WLAN stick.
Lot of people have installed Spider outdoors, an did not face any problem.
Have you noticed that the TV antennas & Satellite Dishes installed outdoors on roof top are not better protected than your DIY Spider, and still survive weather for years.
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abcd567
The 1/2 wavelength is from tip to coax connector. I must re check the 1/4 wave but I don’t think there was any noticeable difference. There certainly is a lot of traffic in the states
The gain of 1/2 wavelength each limb is higher than that of 1/4 wavelength each limb, but due to high impedance its advantage is lost.
1/2 wavelength limbs impedance = 300 to 400 ohms
1/4 wavelength limbs, impedance = 75 ohms.
Hence 1/4 wavelength limb dipole has nearly perfect impedance match with coax + receiver which also have 75 ohm impedance.
[quote=“abcd567”]
Performance with the shade was better than without. Also, I don’t think being too big is a problem for a ground plane. Being too small is, though. At some point, there is a drop in improvement when extending the ground plane, but I didn’t think it was 1/2 wave. Note that some radio antennas mounted on the ground effectively have an infinite ground plane.