Here is construction details for a simple but effective antenna for 2.45Ghz wireless lan use. This antenna is suitable for feeding a sky mini dish. It will give you a gain of around 10Dbi. Actual gain of course will be dependant of final tweaking of the antenna. Tested with a sky mini dish and has had a good contact over 6km.
The construction of this antenna is simple, and does not need much explanation. The connector should be of N-type or SMA which is suitable for these frequencies. The probe which is attached to the centre pin of the RF socket is made of brass PCB spacers – the type of which you use to support the motherboard in your PC. Get one of these spacers, and file down the thread so it will fit into the bucket on the rear of a type N socket. Make sure this spacer is squared up etc. Next, screw in a screw of the correct thread. When you adjust this screw, the effective length of the probe will change because the screw can be screwed fully in or out etc.
If an swr meter is available for 2.45Ghz, then the adjustment can be made to the length of the probe to minimise the SWR. Put your wlan card on the channel you’ll be using, and adjust for minimum SWR. Alternativly, put the wlan card on channel 7 and adjust, This will then give you a good match over the band.
The hole in the top of the tin opposite the probe is used for adjustment of the length of the probe. Dont forget to use a non-metalic adjustment tool to adjust the length of the probe. A metal tool such as a screwdriver will affect the SWR.
For better results, feed a small dish, such as an old Sky mini dish with this tin – can feed. We have done this, and have gotten great results – over 14Km’s in fact.
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