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Author Topic: 9 Db Collinear Antenna  (Read 3241 times)

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9 Db Collinear Antenna
« on: August 17, 2010, 01:01:06 AM »
Hi all thought this may be of Interest to all those looking for a little extra range from their Radar box and don’t want to use a preamp.
Ok before we start a point that needs to be said ,as this antenna has a lot more metal up in the air compared to a standard half wave antenna or the antenna supplied with the unit, you may by more prone to a static discharge problems causing your radar box to become deaf or to stop working ,this is partly due to a poor design in the radar box front end ,so I always disconnect the antenna when not in use and when the weather is looking bad . So the risk is yours should you decide to use it. Sorry Air Nav, great product but this is one area that really needs to be looked at If the Radar box is to be used safely on an outside antenna, but that is a topic for another day.
The 9Db figure is calculated not measured as I don’t have access to the test equipment do that but as you can see from the screen shots It works very well. My original antenna was a half wave dipole 20 feet off the ground , this was removed and the Collinear was fitted in exactly the same place using the same feed cable.
All this aside there is no substitute for a good location so if you stuck between buildings or a lot of trees you will not get ideal results no matter what antenna you use, my location is fairly clear from obstructions. Remember at this frequency propagation is line of sight  or like a torch beam so even a wet tree will act like a shield.     
Rather than fill up this forum with pages of details anyone interested in the construction info can send me an Email and I will be more than happy to send them to you . This antenna is very easy to build all you need is soldering skills , a multi meter , some PVC pipe ,coax and your away.
Email   [email protected]
This antenna type of antenna has been around for a long time so I am not laying claim to its design I would just like to share its benefits for other to enjoy.
See before and after screen shots from my location here at my work. A second antenna was built for home ,it is higher and more than trippled the range but I did not take a screen shot of before I used this antenna, sorry.
Cheers , Geoff.