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Extending Mobile Signal Aerial for Gates

Postby jeremymbwilson » Fri Mar 27, 2020 8:26 am

I am renting a house that has electric gates and have installed a sim card in the controller so that I can send a text message to the gates to latch them open or closed as needed. The problem is that the little aerial to catch the 4G signal for the sms messages is tucked (a) behind the brick gate posts and (b) behind a very large tree. I would like to move the aerial to on top of the gate posts, but there is not any slack in the wire.

My question is (well, are !):

1. Do I need special wire to extend the signal to the aerial or will any wire be sufficient ?
2. As long as I get a waterproof connector, will that be OK for me to extend the aerial wire or do I need any special connector for a 4G aerial ?

Apologies for my ignorance, but I know very little about 4G wiring, etc. !

Many thanks in advance.

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Postby Mr White » Fri Mar 27, 2020 11:30 am

Believe it or not cable for aerials such as you have is calculated so that it will work as expected. If its length is wrong (altered) it can detract from the signal. (Will not work as it should)
Also the cable is often a specific impedance for the task (Again so it does not detract from the signal)
Joints in such cables can also cause problems. Not to mention it will be a screened cable.

All that said, can you not move the whole controller or failing that get in touch with the manufacturer as there may be an aerial extension kit available.
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Postby jeremymbwilson » Fri Mar 27, 2020 12:04 pm

Thanks, Mr White. I never knew that there was so much involved. Unfortunately, moving the controller would involve a lot of work, so I might just have to learn to live with it - frustrating, but one of those things.

I will investigate the aerial extension kit idea, though.

Thanks, again.

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Postby ericmark » Sat Mar 28, 2020 11:16 am

As @Mr White said, aerials are complex, it does not really matter what frequency the same principals are valid, but as the frequency goes up effects are more marked.

We would see phrases like correctly terminated, and this did not simple mean ensure screws tight, it refers to matching the impedance, also length of cable, I remember with a 2 meter wave length thinking I would tidy up cables by cutting off the extra, and had to make up new cables as my signal strength was reduced.

However with my hobby there were meters both built into radio and after radio which could measure power out, power in, and most important power reflected back into the radio.

If the leads are connect lengths and all it tuned correctly 100% of the signal will be transmitted, but if not some of the power is reflected into the radio which can cause over heating and cause components to fail, the CB guys called is SWR stands for standing wave ratio, which is the percentage of signal transmitted compared with signal reflected.

The meter for high frequency was not too expensive, but as the frequency goes up so does the price and also the leads used to connect it mean it becomes inaccurate and instead of wire pipes are used, some radio hams do play with micro waves, but the maths is beyond my ken.

So mobile phone frequency is not simply one, and where using multiple frequencies it gets really complex, even with a site hand held radio if the rubber cap was knocked off the stub aerial that was enough to cause the radio to interfere with other site radios, and become deaf.

There may be a car kit you can use, but it would likely be easier to move the whole radio.
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