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Author Topic: New Antenna - first impressions  (Read 9022 times)

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bratters

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New Antenna - first impressions
« on: April 23, 2010, 07:37:23 AM »
At last I’ve got a “proper” 1090 aerial up on the roof. Until now I’ve been content with some goodish results from my supplied aerial high in the loft.

I tried to do some pre-purchase research however until someone comes up with a definitive side by side “Which Antenna” test, there are only our own personal evaluations and opinions to go on with few actual performance comparisons.

I finally opted for the “controversial” Radarmax X2 from Anchor Supplies in Nottingham. I say controversial because this aerial greatly disappointed our friend “Orkney” up north but on the other hand it highly delighted our friend “G0HWC” down south. So this is a third opinion from a man literally in the middle.

My choice was influenced by a sensible price, a local(ish) company who supplied my original RB (and gave good after-sale service in exchanging it when it died) plus the opportunity to deal directly with the experienced radio amateur who both designed & built the product. He also advised on the appropriate coax and connectors and made up the cable for me.

My house is 110 feet asl in a flattish area, with housing on three sides but open fields for 300m to the south. There are some trees around but the serious obstructions are mostly topographical, especially to the south west. The nearest airport is EGNX at 15nm but because of an intervening ridge, 3000 feet is the lowest I receive for landings/takeoffs.

The antenna was gable end mounted with 7m of RG213u coax feeding into and along the loft floor to where the box is sited. There is a 12m USB feed down from the box to the PC in a back bedroom - now converted into a study/studio.

A measure of the aerial’s performance can be judged from the “before and after” pic. below.  This illustrates the much enhanced all-round coverage with even a range increase to the protected southwest. I now enjoy a near 360° field of view with ranges between 150-200nm.

It is worth noting that in spite of the increased height of the aerial (2 metres plus), my previous maximum range of 205nm has shown only a nominal increase. Nevertheless, overall there has been a dramatic improvement in the Polar Diagram with the new antenna.

What the pic. cannot show is the numbers and I have made a rough table.

My initial comparisons are:

MyFlights historically 50-100 standard; 100-140 busy; 140-160 peak.
MyFlights  yesterday 110-160 standard; 160-210 busy; 210-240 peak. 
NB  my timeouts are set at 5secs.

MyLog Aircraft total (0700 - 2200) historically between 1500 - 1650
MyLog Aircraft total (0700 - 2200) yesterday                  1965


Scrutiny of the map shows that the major increase in flight numbers does not come as a result of the expansion to the northeast on the polar diagram. The increase comes mainly from areas that were already covered by the old set-up. Therefore the new antenna is pulling in far more signals from pre-existing areas. I particularly note the disappearance of my “black holes” into which flights temporarily vanished before reappearing further on.

More analysis on the figures is needed and they could be misleading. I suspect that the skies have rarely been busier than they are right now as the airlines battle to overcome their backlogs. When things get back to normal, I’ll have a clearer idea of exactly what the numbers are and from where and how the increases have arisen.

So am I happy with my new antenna? With up to 240 in MyFlights and 150-200nm range in virtually every direction, you bet I am!

The product: http://www.anchorsupplies.com/radarmax.htm

DISCLAIMER
I have absolutely no connection whatsoever with the supplier beyond being an occasional customer. I would have had no reservations about slaughtering this product had it been a dud.

John.

bratters

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Re: New Antenna - first impressions
« Reply #1 on: April 23, 2010, 07:40:17 AM »
Further to my posting, this is the mounted antenna.

orkney

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Re: New Antenna - first impressions
« Reply #2 on: April 23, 2010, 08:40:17 AM »
hello

I am glad this worked for you, however did he actually recommend 7m rg213 since when we bought our one he only recommended rg213 for over 20m and rg8m for 20m and under. Also I noticed with the x2 everyone claims it works so they must have learnt how to tune an antenna not just cut up coat hangers.

I am sorry if we have offended anyone but we are still really annoyed since not only did we loose or money but also it nearly made us forget the whole idea of getting an outside antenna.



« Last Edit: April 23, 2010, 09:53:37 AM by orkney »

bratters

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Re: New Antenna - first impressions
« Reply #3 on: April 23, 2010, 09:40:03 AM »
Hello Orkney

Re Coax: 

Although I only needed 7 metres, I nevertheless specifically requested the best coax I could afford without total overkill. After some discussion we settled on RG213 which they recommended as a quality which would virtually guarantee no losses. The spec. was perhaps OTT but I was not prepared to spoil the ship for a bobsworth of tar.

I was aware of your "difficulties" and with those in mind made sure I checked that the antenna was working efficiently before letting the erector off the premises!

Sorry you had such trouble but obvious can't comment. Is the situation irretrievable?


orkney

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Re: New Antenna - first impressions
« Reply #4 on: April 23, 2010, 10:12:31 AM »
hello

the reason I said about the coax is because I know now that  20m of rg8m is basically ridiculous at 1090mhz because of losses  so I was just wanting to know if they had changed their story on losses or what was the reason for the your short run of rg213u.

"Is the situation irretrievable?"     -yes the only gain our antenna had was £50 to anchor supplies.


smcm

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Re: New Antenna - first impressions
« Reply #5 on: April 24, 2010, 08:59:45 AM »
I don't know this particular antenna, but surprised the manufacturer is advocating the use of SO239 / PL259 connectors at a frequency of 1090 MHz.

These connectors are well known as not being of constant impedance throughout and although they are used up to VHF they are not really recommended for UHF and above.

It's also worth noting that that coax losses are only accurate if the coax is terminated with the correct impedance - any mismatch due to connectors or even the antenna itself can greatly increase losses.

bratters

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Re: New Antenna - first impressions
« Reply #6 on: April 24, 2010, 10:14:20 AM »
Yes smcm - we discussed that and it's also mentioned on their website. N was always an option but they reckoned they could find no differences when testing. Customers get the choice though which is fair enough.

I dunno - sometimes I think these things can get a bit like hi-fi - just where do you stop and at what stage is the difference so negligible that it can barely be measured.  Law of diminishing returns etc...

Have to say for £50 quid I'm not going to quibble - dead straighforward, no pre-amps, no messing and results that have given my hobby a totally new dimension. I've always thought RB was good, but this takes it to a new level.

Now if we can just get those databases sorted out...    :)

smcm

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Re: New Antenna - first impressions
« Reply #7 on: April 24, 2010, 10:55:15 AM »
Hello bratters

I tend to agree about some measurements - I'm sure a dB here or there doesn't make any practical difference.  I'm using a Wimo antenna with a fairly short run of Westflex and this works fine for me, although I have seen some reports that it's not a good antenna.

Also prefer to work on "kiss" principle and keep installations as simple as possible, but don't stint on quality of coax and connectors where possible - the antenna is the most important part of any radio system after all.

Amazes me that folk will buy a £1000 plasma tv, or whatever, but are reluctant to replace their 20 year old tv antenna and waterlogged coax or rusting satellite dish !

dunc8543

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Re: New Antenna - first impressions
« Reply #8 on: May 12, 2010, 03:46:40 PM »
Hi all,

I have just bought the Radarmax 2 like Bratters and thought i would share my experience with you.

I travelled to Anchor Supplies and bought the Radarmax and Airmax aerials after a long and very interesting chat with Rob Taylor, who answered any questions i had and also offered helpful advice.
Upon getting back to Leicester, i was a little annoyed to find that Anchor had forgotten to put the adapters to connect to my radarbox and also my scanner in with the aerials and cable etc.
A swift e-mail brought them winging to Leicester postage paid courtesy of Anchor.
I have today had them both fitted to my chimney and the results are staggering!

Pre Radarmax i was getting 30-40 aircraft on screen at any one time, now it is 140+.
A few moments ago there were 187 showing.

To sum up so far, i am very happy with this item and would recommend it.

As with Bratters I have NO connection whatsoever with Anchor or anyone who works there.

Dunc

bratters

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Re: New Antenna - first impressions
« Reply #9 on: May 12, 2010, 03:51:13 PM »
Have you got a screenshot Dunc?

dunc8543

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Re: New Antenna - first impressions
« Reply #10 on: May 12, 2010, 03:58:14 PM »
How do i do that?

bratters

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Re: New Antenna - first impressions
« Reply #11 on: May 12, 2010, 04:59:59 PM »
File/screenshotshot/savetofile... then add as an attachment to your next post.
You'll possibly find it in C/progfiles/airnavsystems/screenshots.

dunc8543

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Re: New Antenna - first impressions
« Reply #12 on: May 12, 2010, 05:43:29 PM »
Hi Bratters,

Think i have don eit right

Dunc

bratters

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Re: New Antenna - first impressions
« Reply #13 on: May 12, 2010, 07:08:36 PM »
How's the scanner aerial dunc?

dunc8543

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Re: New Antenna - first impressions
« Reply #14 on: May 12, 2010, 08:56:42 PM »
Hi Bratters,

To be honest i haven't really tried that properly yet.

I had it on for a few mins earlier and had some very strong and clear comms from AWACS and as i write this have nice and clear 2 way unknown RAF air-air doing simulated ground attacks.

So i am looking forward to leaving it on all day tomorrow and seeing how it performs.

Dunc