Antenna


Choice and location of antenna can make all the difference in your installation.  XL Provide a range of standard antenna for most circumstances, however - should you need something out of the ordinary - please don’t hesitate to ask! Please remember to check the local regulations before installing any gain antenna.

Here is a brief summary of some of the antennas most commonly used for radio data modem installations along with hyperlinks to their data sheets. XL are always pleased to discuss your application and to offer advice on which antenna is the most suitable for your application.  Remember if you need range, you will need to sight the antenna as high as possible to get it into free space. Always check that you are complying to local regulations regarding transmission power.  If you require something not listed then please ask, it is more than likely that we can help you.



 

Antenna Cables 

In order to place your antenna in the prime location i.e as high as possible and in free space, XL can provide low loss cable with suitable connectors to your specification.

This is a useful too to calculate loss incurred from long cable runs http://www.timesmicrowave.com/cgi-bin/calculate.pl

 

Simple explanation of DBD V DBI

If you can imagine looking at an antenna from the side and ‘seeing’ the RF field that is generated it would look like the patterns shown below.

You can see the (Gain) difference in dBi verses dBd. Also you can see the pattern shape when using a Yagi and the gain in one direction.

 

Antenna Length Calculation

300 divided by the transmit frequency in Megahertz will give you the wave length at the transmit frequency.

 

Divide the wave length by four and you will arrive at a quarter wave antenna.

 

Get out your digital calculator!

 

Therefore:-

 

300/458.5MHz = 0.654 Metres or 654mm /4 = 0.163 Metres or 163mm

 

Thus a ¼ wave whip at 458.5MHz is 163mm

Remember to measure the ACTUAL antenna minus any base it may have.

 

 

http://xlsystems.co.uk/KG-2222.pdf

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