External phone aerial

**Michael2** · 1st August 2006, 11:08 PM

Now that the ORANGE CDMA network has been shut down and I've been relegated to the 3 GSM network (half the time roaming on the Telstra network even in suburbia). I'm after a means to trying to recoup my rural mobile phone range. It was so good being out in the bush and even in valleys in the high country having CDMA access.

Anyway, my question is - how good are the big exteral aerials compared to the small stick on glass types?

I did a quick search on ebay and found that both types were rated to a 5dB gain, and a mate who does a lot of car phone installs says he's found no difference between the two (but he's mostly urban). So can anyone tell me how well they perform, is there any feature to look out for? or beware of? etc.

A big 5dB aerial on a bullbar Vs a 5db aerial on top of the windscreen still gives me the same height. I could put a removale aerial on the Kaymar rear light holder, so it can stay low while driving, but still be lifted up for better access - but that means a longer cable and always flexing when the rear door opens.

The Defender came with an older Nokia & car kit installed, so I'll just hook the aerial to the existing phone and buy a $20 prepaid SIM (the 3 SIMS won't work) just for remote area calls.

**Tusker** · 2nd August 2006, 11:08 AM

Answer: next to nothing.

CDMA is analogue. The signal just gets weaker & weaker, much like the car raiom till it drops out.

GSM is a European spec, not designed for long distances. Theres a bounceback in the technology. Get 60 kms from the tower, & the call's gone. From maximum to nothing. May not be 60ks, might be 20, I can't remember. But a high gain antennal cannot extend coverage.

I've got one - it will help here & there where the signal is marginal, and within range. There's one spot SW of Coonabarabran where I can get coverage, whereas with the through-glass jobbie beforehand I couldn't.

Bring on the new 3g on the CDMA frquency..

Regards
Max P

**JDNSW** · 2nd August 2006, 12:03 PM

Originally Posted by Tusker

Answer: next to nothing.

CDMA is analogue. The signal just gets weaker & weaker, much like the car raiom till it drops out.

GSM is a European spec, not designed for long distances. Theres a bounceback in the technology. Get 60 kms from the tower, & the call's gone. From maximum to nothing. May not be 60ks, might be 20, I can't remember. But a high gain antennal cannot extend coverage.

I've got one - it will help here & there where the signal is marginal, and within range. There's one spot SW of Coonabarabran where I can get coverage, whereas with the through-glass jobbie beforehand I couldn't.

Bring on the new 3g on the CDMA frquency..

Regards
Max P

CDMA is not analogue - it is just as digital as GSM, but as you state it has much longer range, and a car antenna really helps, where it does not help much for GSM - and i think your 20km is nearer than 60km!

The "new 3G" is actually a form of CDMA (not compatible with the current CDMA) and because it operates in the same band and is a similar system, should have much the same coverage, except it will have all the 3G bells and whistles including wide band.

**Michael2** · 2nd August 2006, 01:45 PM

Thanks for the feedback, it clarifies things a bit.

It sounds like it's not worth spending too much money on it then. I may as well stand on the roof rack to make a call, either I'm going to hit the repeater or not.

Has anyone used the aerial boosters that stick to the phone. I saw them on ebay. Do they work? If so, it might be cheaper to just stick one of those to the 3 phone. (see pic below)

What if I carried a packet of balloon, a bottle of helium and a long fishing line with a metallic filament in it. I could run an aerial 500' or so up into the air and see what kind of reception that would give me. Provided I didn't use it in a thunder storm

**JDNSW** · 2nd August 2006, 07:23 PM

Originally Posted by Michael2

Thanks for the feedback, it clarifies things a bit.

It sounds like it's not worth spending too much money on it then. I may as well stand on the roof rack to make a call, either I'm going to hit the repeater or not.

Has anyone used the aerial boosters that stick to the phone. I saw them on ebay. Do they work? If so, it might be cheaper to just stick one of those to the 3 phone. (see pic below)

What if I carried a packet of balloon, a bottle of helium and a long fishing line with a metallic filament in it. I could run an aerial 500' or so up into the air and see what kind of reception that would give me. Provided I didn't use it in a thunder storm

I haven't seen the gadgets referred to, but the problem with any better antenna, including the balloon idea is that with GSM it will not extend the range significantly because of the way the system works, although it will improve reception in poor reception areas within the service area. I have read of tests using them from aircraft, and the range is not increased all that much - apparently the system gets confused, although there seems to be disagreement on why it does.
John

**rangieman** · 2nd August 2006, 07:44 PM

Originally Posted by Michael2

Thanks for the feedback, it clarifies things a bit.

It sounds like it's not worth spending too much money on it then. I may as well stand on the roof rack to make a call, either I'm going to hit the repeater or not.

Has anyone used the aerial boosters that stick to the phone. I saw them on ebay. Do they work? If so, it might be cheaper to just stick one of those to the 3 phone. (see pic below)

What if I carried a packet of balloon, a bottle of helium and a long fishing line with a metallic filament in it. I could run an aerial 500' or so up into the air and see what kind of reception that would give me. Provided I didn't use it in a thunder storm

OK funny thing i just bought a phone off ebay and it came with one of these as a free gift

i put it on last night and nothing so save ya bucks its a joke

**Tusker** · 3rd August 2006, 11:33 AM

Brain fade.. meant to say CDMA operates similar to the old analogue..

And I have an idea boosters on phones, ceratinly CB radios, is illegal. Used to be quite common though.

Regards
Max P

**JDNSW** · 3rd August 2006, 04:30 PM

Originally Posted by Tusker

Brain fade.. meant to say CDMA operates similar to the old analogue..

And I have an idea boosters on phones, ceratinly CB radios, is illegal. Used to be quite common though.

Regards
Max P

That's OK - we all have our moments!

Power amplifiers on both phones and CB radios are, as you say, illegal, and are still quite common. I think there is also a limit on the antenna gain you are allowed as well, again in both cases. Generally speaking amplifiers are not very useful except in the case of CB for talking over the top of others and they do extend the range with HF (27MHz) CB, and also extend the range of CDMA, although not as much as you might think seeing you need two way communication, and they do nothing for reception. A higher gain antenna will help though.
John

**Redback** · 7th August 2006, 09:14 AM

Just a comment from the installer of our CDMA incar kit when i asked about an external antenna for it to improve the signal, he basicly said they are a waste of money, the anteena suplied with the kit is the best signal you'll get, he also said i'll sell you one if you want, it means more money for me, but i'm telling you, you'll be wasting $100.

I took his advice, i'm glad i did cause i found out later he was correct, i tested ours against a mate with an external antenna, made no differance, infact his in some places had less signal

Baz.

**p38arover** · 13th August 2006, 10:27 AM

Originally Posted by JDNSW

CDMA is not analogue - it is just as digital as GSM, but as you state it has much longer range, and a car antenna really helps, where it does not help much for GSM - and i think your 20km is nearer than 60km!

Unless it is an Extended Range Cell, it is about 35 km owing to propagation delay (the time for the signal to get to the phone from the GSM base station or vice versa). The issue is that of timing, not signal strength, because GSM uses TDMA - Time Division Multiple Access (it also uses FDMA - Frequency Division Multiple Access but let's disregards that while CDMA is Code Division Multiple Access) - and timing of the multiple signals from multiple phones becomes critical.

This link gives a fairly easy to understand description: http://www.geocities.com/gsmmobilere...mradiolink.htm

Ron

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