Ground Plane for FA Antenna?


#1

Has anyone tried to put a ground plane on the FA antenna? Thinking old steel, aluminum pizza pan with a hole in the middle, slipped over the top. Rests on the mounting pole…

Not worth the trip up to the roof?

Scott


#2

Not worth the effort, the antenna is designed to work without a groundplane. You would probably adversely affect the reception pattern if you did.


#3

Try it, but I don’t think it’ll help. It may actually degrade the radiation pattern. The following quote is from the RTL-SDR Blog:

“From the image it looks like the antenna may be a sleeved dipole + whip + impedance matching design, or something similar. This design is somewhat of a collinear design thanks to the additional whip which also gives a flatter radiation pattern with more gain direction out towards the horizon. These antennas are omnidirectional (they receive equally from all directions) and have a higher gain compared to most other omnidirectional antennas, but their radiation pattern is flattened and directed more towards the horizon. This is a good thing for receiving planes that are far away as they will be at lower elevations, but aircraft at higher elevations relative to your antenna may be received poorer. Although, it is likely that any aircraft at high elevations to your position will be closer to you anyway, and thus have a stronger signal making the reduced gain at higher elevations less important.”


#4

I just though of something about a ground plane for this antenna, How about putting it into a mast pipe, just the base portion and the mast pipe being the same length as the antenna itself?


#6

That thought was probably worth keeping.


#7

It is a question worth asking, i too have wondered if this would assist as when i changed from my Spider to FA ant i dropped range and hits and wondered if this was due to no ground plane.


#8

I wonder if mounting the metal bracket atop a metal pole, versus a non-conductive pole, makes any difference to the antenna’s operation.


#9

Must be conductive, else no radiation would be absorbed or reflected. The use of a ground plane is to electrically double the effective radiation length - - typically from 1/4 wave to 1/2 wave. When properly installed, the RF pattern can be ‘pulled’ down to lower the skyward waste and ‘push’ the horizontal reach. The ‘ground plane’ is as the name suggests, grounded and must not connect/touch the live portion of the antenna.


#10

I have an old metal (steel) pizza pan just dying to have a thrill ride on top of my house. Will report out early next week how it goes.

But hmmmm, grounded. it will touch the base of the FA antenna (well grounded).


#11

I was just wondering if the design of the FA antenna will result in any variation in performance when mounting it on a metal vs non-metal pole. I believe, but am not certain, that for the FA antenna it makes no difference since the antenna is already well balanced internally.


#12

If you changed nothing else, then it sounds like you have a connection problem. There is no way that a spider will out perform the FA antenna (unless defective of course).


#13

Check the plug going to the FA antenna, or adapter, if using one. I had the same performance between the Quick Spider and the FA antenna, until I checked the adapter.

Performance with the FA antenna now is 50-60% better than the Quick Spider.

As mentioned on another thread, ensure the N male plug is of the same impedance (50 or 75 Ohms) as the female N socket on the antenna. The impedance itself is not the problem, but the internal dimensions, they are different.


#14

@Dxista I have an N Female to Female F connector from an Amzn seller that visually looks correct with the larger 50 ohm center pin socket, but when I screw it into my length of LMR400 cable it is dead/open circuit . It meters OK so its not electrically defective but appears to be short a few threads and simply does not fully make contact with the N Male on the cable.

I think there are a lot of substandard connectors afloat in the market and I’m accumulating a pile of junk- I know I would appreciate leads on where to find quality hardware without wasting a bunch of money. (If not permissible to publicly post that kind of info here on the FA board, perhaps via private message.)


#15

@belzybob I believe my issue is due to the high gain of the Antenna where the spider is not, also the FA blue dongle also amps up the signal. My scans tell me that i have heaps of 800 and 950 noise due to mobile towers hence the high gain and amping just increase the noise, where as the ground plane on the spider has less noise going to it.

My FA filters should arrive today so hopefully that will at least dump the 800 to 860 noise (not confident for a 950 reduction).

or when my saw filters come from a slow boat from London may assist with the reduction of 4g signal… Lets see if i get a range boost soon…

@skip20092017 the adapters i have, are both the thicker male pin, do you know if that is the correct pin for the Ant? I bought a Ntype to sma cable from GPIO Aust for the Antenna and also a Ntype to Ftype adapter (currently using) and both pins look the same.


#16

@coxyb76 Every possibility that is the case. I was using various ground plane and small co-linear antennas with passable results. Then I put some real time into building a three element co-linear and then got no aircraft at all! I wrote that one off and bought a FA antenna. Same result, no aircraft! After reviewing the signals around me, I realized that the increased gain had taken the dongle into overload as the interference level was now much much worse.

Fortunately a SAW band pass filter did the job.


#17

Some two-and-half year old posts. My help.


#18

One more post from archieves


#19

Other than asking the 14 years old dude behind the counter how would you know if the adapter is 50 or 75 if you dont have both to compare? Is there something the old multimeter can do?


#20

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I used trial-and-error method. Purchased several connectors, each one from a different vendor, but none solved the problem. Finally I added a Filter, and all connectors started working OK :slight_smile:

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In Feb 2016 I have made following suggestion to FlightAware in my post quoted below:

“I suggest FA ask Amazon to include with antenna sale, the option to purchase various different connectors (to be chosen by the buyer) and ship it along with the antenna in the same box. This will help the buyer a lot and avoid mistakes in ordering connectors / pigtails / patch cables, and will save time in procuring these after the buyer receives the antenna.”

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#21

I actually ordered the pigtail with the FA Pro dongle from GPIO, https://www.buyraspberrypi.com.au/shop/sma-male-to-n-type-male-pigtail-cable/ Icompared the N type to me generic N to F type adapter and they look identical.

I can get a sma to f type adapter to connect to my RG6 or maybe ill just fork out the $30 and just buy 5 meters of SMA extension cable. https://www.jaycar.com.au/low-loss-sma-extension-lead-5m/p/WC7824