best antenna

[abcd567]

I was seeing similar results on the long run of coax with both the DVB-T dongle and the FR24. The preamp doesn't do much good once you have lost the signal coming down the line. An amplifier should be mounted as close to the receiving antenna as possible so you still have a good signal and can boost it going into the longer run of coax toward the receiver.

Yes, you are right. The best location of in-Line Amplifier is closest to Antenna.
Please see where I have installed my pre-Amp in this thread's posts #75, #255, #254.

[abcd567]

a VERY quickly (all of 30mins) made 4 element collinear made with RG59U tied to a wooden stick to keep it strait. I know this is 75ohm cable into something expecting 50ohm's but it hasn't done to bad, no trimming just followed the instructions (it's only on a 1 meter tail)

[ATTACH=CONFIG]3852[/ATTACH]

the antenna was left open ended. proves that not only are these antenna's easy to make its hard to get them terribly wrong too.

Good that you have done test by Network Analyzer.
Now do the acid test: connect the antenna to an ADS-B Receiver (Like DVB-T USB Dongle etc) and plot the maximum distance it pickups the planes.
This will show how good, bad or terribly bad is the antenna.

[SpaxmoidJAm]

i have a dvb-t dongle lined up to do just that, just got to set it up, i'd like to do it on mast but for convience i may just have to settle for the roof space. At least the location would be the same for each antenna.

[abcd567]

If you have a comprehensive home insurance, you are covered for fire, flood, & burglary. You pay monthly or qurterly premium.

If you have a good in-Line Amplifier, located close to antenna, you are covered for a lousy antenna, cheap high loss coax & long run of coax. You only pay one time small amount to purchase the amplifier.

[HighlyCool]

If you have a comprehensive home insurance, you are covered for fire, flood, & burglary. You pay monthly or qurterly premium.

If you have a good in-Line Amplifier, located close to antenna, you are covered for a lousy antenna, cheap high loss coax & long run of coax. You only pay one time small amount to purchase the amplifier.

I have never been an advocate of trying to compensate for a bad antenna or garbage feedline with a preamp. I had a friend who used to spend big bucks on his tower and antennas, then would reuse old lossy coax that had been out in the elements for years. He would mount a preamp on the tower and try to get his received signal level back to where he would have been if he had just spent the money he paid for the preamp on some good coax. The thing I don't like about preamp's is they also amplify noise as well as the signal, so you basically have 'other stuff' being boosted to get down the feed line. Sometimes you have no option but to make a long run of coax and need a preamp to help, but if you can do it all with a good piece of coax you are better off.

[peterhr]

Yes, BUT, people need ot understand that even with a great antenna if you pair it up with cheap coax and/or a long length of it, it will really impact your reception. When I had my DVB-T dongle up with a good antenna it had a fairly long run of coax. I was only hearing planes out to about 350 km, even with the FR24 receiver. When I installed the FR24 receiver on the permanent antenna with a shorter run of coax the reception distance increased to approximately 500 km. That is a major improvement.

Most just need to know what to do to make a reasonably good low cost antenna to get started. Like you they can tweak it later. Let's not drown them in theory before they have started to swim.

Sent from my Nexus 4 using Tapatalk

[abcd567]

Most just need to know what to do to make a reasonably good low cost antenna to get started. Like you they can tweak it later. Let's not drown them in theory before they have started to swim.

Sent from my Nexus 4 using Tapatalk

You are right. We should suggest something easy and practical for beginners.

To start with, the best antenna in my opinion is a Coaxial Collinear. A 3-and-1/2 element is a good choice as it is a good compromise btween skill+effort and results.

If some one wants an easier antenna, a half-wave dipole is good, as it gives much better result than the monopole stock antenna supplied with DVB-T Dongle.

Half-wave dipole's easiest version can be built simply by seperating core & braid for last 68mm of coaxial cable, bending sepatated core 90 degrees up, separated braid 90 degrees down, coax cable itself horizontal for short length, say 150mm, then taking vertical down direction to reach receiver.

An alternate construction method for half-wave dipole, requiring little more effort than above, is shown in my previuos post #255,

[HighlyCool]

Most just need to know what to do to make a reasonably good low cost antenna to get started. Like you they can tweak it later. Let's not drown them in theory before they have started to swim.

Sent from my Nexus 4 using Tapatalk

It's best to know up front what will help them. Don't scrimp on the coax or the antenna; they are the most important part of your system.

[abcd567]

Most just need to know what to do to make a reasonably good low cost antenna to get started. Like you they can tweak it later. Let's not drown them in theory before they have started to swim.

Sent from my Nexus 4 using Tapatalk

It's best to know up front what will help them. Don't scrimp on the coax or the antenna; they are the most important part of your system.

I agree with peterhr that beginers need to know a good practical antena, and improvements can follow. For beginers, knowing all details upfront may be so confusing, they may quit, or "drown before swiming", as peterhr has said.

[peterhr]

Agreed - could the relevant bits be extracted and put into threads - "best antenna - coco with no amplifier", "best antenna - coco with amplifier" and "best antenna for use in a hi-rise window"

So this was the post that started this discussion - who would like to extract the info and start the new threads (Ideally abdc567 since that the is member who has done most work on this) - others then can add detail on improvements. How to build and how to best connect to a dongle. People who buy commercial receivers as a startup are more likely to buy a commercial antenna and not be in the DIY world.

I'd like to encourage first antennas to bamboo poles etc so users can tweak them before sealing them into PVC / fibreglass tubes ... admitted an unsealed antenna attached to bamboo in the wet is not ideal.

[charan]

Now i made a good co-co antenna and its good i tested it for 2 weeks whats the next best antenna to try? for better reception>?

[peterhr]

Now i made a good co-co antenna and its good i tested it for 2 weeks whats the next best antenna to try? for better reception>?

Read through about what's the best way to 'finish' the top of the antenna or increase it's length. What will make most difference is height - can you put it higher?

[charan]

Read through about what's the best way to 'finish' the top of the antenna or increase it's length. What will make most difference is height - can you put it higher?

yes i can but the only problem is if i increased the height of the antenna there is lot of noise building up i donno what to do for that.. someone stated that as EMF and suggested a static bag to cover the dongle but it didn't help can you suggest me anything to finish the top? thanks

[FRC]

Hello everyone,

i´m just following this tread a while and my doubt is about interferences near 1090Mhz.
I just built an antenna from this site: http://www.qsl.net/py4zbz/adsb.htm#b similar to one described earlier.
1.jpg

What a newbie can do to solve this.

Thx.

Marcelo.

[peterhr]

yes i can but the only problem is if i increased the height of the antenna there is lot of noise building up i donno what to do for that.. someone stated that as EMF and suggested a static bag to cover the dongle but it didn't help can you suggest me anything to finish the top? thanks

Hello everyone,

i´m just following this tread a while and my doubt is about interferences near 1090Mhz.
I just built an antenna from this site: http://www.qsl.net/py4zbz/adsb.htm#b similar to one described earlier.
[ATTACH=CONFIG]3860[/ATTACH]

What a newbie can do to solve this.

Thx.

Marcelo.

Have a look at http://adsb.alle.bg/filter/ for designs of antenna filters. [this doesn't look easy!]