FlightAware Discussions

Antenna Ground Plane

Sure, I understand that (and I agree).
However. abcd’s results above indicate ‘his system’ which incorporates a PCB antenna is a poor performer.

Without a reference for the FA filter+orange stick combination in comparison to the green Airnav stick, it could just as well be that the problem is not the antenna.

Pretty sure in some previous post the green Airnav stick performed very well with the apparently quite interference rich environment in Toronto :wink:

It may be that the interference is partly from below, that would make dipole antenna especially handicapped in that location when not combined with adequated filtering.

Yes, absolutely.

20chr

Your comments are valid if someone wants a “performance” antenna. If you look at the OP’s first post, he is not looking for it. What he is looking to is a “starter” antenna.

A “performance” antenna is either a good commercial antenna (like Flightaware or Jetvision), or a DIY antenna made by an experienced hobbyist who has necessay technical know-how, skill and test equipment.

A “starter” antenna is the one which can be purchased at dirt cheap price, or a dirt cheap DIY which can be built very easily by a novice without any technicel know-how, does not need much skill, and without need for test equipment.

Both the PCB antenna, and mag-mount whip, cut to 1/4 wl, and placed on a metal plate, fall under gategory of “starter” antenna.

P.S.
When I wanted “performance” antenna, I purchased Flightaware 26" antenna and am using it for Station # 76000. :slight_smile:

The OP actually asked for a portable antenna.
After the question was answered, the thread started going off topic.

Does that describe you when you built your first coco?

No, and all my attempts to make high gain colinears (coax & wire) have failed, and that is how I learned what I have said in my last post.

.

:ast night at about 1:00 am I swapped the two antennas. Waiting for stats to build up. will need few days.

As a quick check, the instantaneous message rates and plane count on two instances of dump1090-mutability:

Station 5252 :
Mag-mount 1/4 λ GP (cookie can)
1m RG174 coax
FA Filter + FA Prostick Orange
instance-1 of dump1090-mutability & piaware

.

Station 6396
PCB 1/2 λ Dipole
1m RG174 coax
RadarBox24 FlightStick Green
instance-2 of dump1090-mutability & piaware

I’m sitting in a hotel foyer in Russia trying to look at the status on s phone. It appears that 6396 was doing slightly better and when you changed them over the difference became marginally more obvious.

Does this mean the pcb dipole was initially better and the difference was moreapparent when you changed it over or have i misinterpreted the situation.

Thanks,

S
P.S. it is raining cats and dogs in St Petersburg

I see this more as normal deviation. My station is where it is since weeks including the antenna position. But i am having ups and downs per day in the same range

Bit you have only one station

S

Thank you @geckoVN for the nice technique for messages less than 20 characters. :slight_smile:

[spoiler]20char[/spoiler] = 20 char

Just now (2 pm EDT, today Sept 14), increased gain of both stations 5252 & 6396 from 45 to -10 after noting following:
Messages > -3dBFS (1.8% of messages)

Will watch the results.

image

Could it be that the dipole is in a bad position? There is a shadow behind it, is that a window frame? If that is the case it would need to be a 10 cm higher.

The entire area behind the blinds in this photo is glass. The lower window frame is 50 cm below the PCB Antenna. These is a middle frame which is also 10cm above PCB antenna, and then again there is glass up to ceiling. Please see attached sketch.

EDIT: May be the the two pieces of adhesive transparent tape I used to stick the PCB antenna to blind is giving you impression of shadow of a window frame.

image

Maybe you got a dud antenna, mine always seemed to work rather well.
Or your mag base cantenna is just very good :wink:

Or yet another possibility: interference which is blocked by the can lid but can couple into the PCB antenna from below!

I am considering to remove the PCB antenna from blind and place it very close to mag based antenna, but I have to find some sort of support for it. (also expecting objection from wife. It is currently tapped to the blind, is of same color as blind, merges with it and barely visible)

Just now (4 pm EDT, today Sept 14), reduced gain for both stations 5252 & 6396 from -10 to 49.6 after noting following:
Messages > -3dBFS (24.2% of messages)

image

Being nowhere near as knowledgeable ( I am still a raw newbie…) as most here, might other variables affect these PCB antennas other than their design? Such as whether that particular version/ design actually is mounted inside a PVC tube or supposed to be ? Admittedly not a huge impact, but I have been curious exactly what effect it has.

I have an experiment I want to do with “failed” collinears that I quickly assumed were not so good, but never actually went so far as mounting them inside PVC. The only coaxial collinear I made that was awesome was the first one I made, where I naively and confidently built it, mounted inside pvc pipe , then tested it. All other “failures” I tried to test naked and unfraid and maybe should have at least slid them into pvc to see if the resonance was improved ( assuming they were minimally off in dimensions)

TLDR: unless you have the same exact PCB ( or other) antenny bare or not bare in the same location you cannot compare.

Sorry, i misunderstood your statement saying the station is performing better with new antenna compared to before