All About Symbian - Nokia (S60) and Sony Ericsson (UIQ) smartphones unwrapped

  #1  
Old 22-07-2006, 02:49 PM
BigRedBall BigRedBall is offline
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Question E61 - CR-47 Cradle - use with external antenna

Hi folks. I posted a while ago about external antennas for the E61. I've now got the phone and the CR-47 cradle (to allow an external antenna to be fitted) and have been attempting to use them with a Panorama GTAE antenna (at the left side of this page). This antenna will only give me GSM reception (if and when it works) - that's all I need. I can use WiFi for data access.

However, it doesn't seem to give me any noticable benefit in signal strength. I realise there's an issue about cable length and quality - the antenna came with 'CS23' cable, which I hope and assume is sufficient. The cable length is quite long at the moment - I plan to cut this down but I would like to establish that the antenna is actually doing something first. I tried it in a moderate coverage area and it seemed to make no difference at all to signal strength. Also, I've also tried the phone in GSM only mode, and again the aerial made no difference.

The phone doesn't seem to 'register' that it's been placed in the car cradle. I would have thought it would switch to a set profile when placed in the cradle, like Handsfree or something. At least then I'd have some sort of indication that it was actually using the antenna. So the questions are:

1. Can anyone who uses the CR-47 with an external antenna tell me what I'm doing wrong?

2. Is the phone supposed to indicate that it's connected to the cradle?

3. Any have tips for mounting antennas? e.g. correct orientation and placement on a house window

Many thanks in advance for any suggestions.

  #2  
Old 22-07-2006, 08:13 PM
bodstrup bodstrup is offline
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Wirelessly posted (Nokia E61: Mozilla/5.0 (SymbianOS/9.1; U; en-us) AppleWebKit/413 (KHTML, like Gecko) Safari/413)

Well, the antenna give you only 4 db og gain, roughly doubling the output of the transmitter. Subtract the loss in cabling and you are probably back at 0 db/no gain or worse. I am using a 15 db antenna to boost signal for wireless LAN, that is a increase in power of a factor32.



I think you need to look at a 15-30 dbi gain antenna - which might be a 1 foot or more parabolic disc.



The value of the antenna you show is mainly to "move" the phone antenna outside a shielding, metal car, not to provide gain over the phone antenna placed outdoors..



Regards, Michael

Last edited by bodstrup; 22-07-2006 at 08:20 PM.

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Old 23-07-2006, 04:47 PM
BigRedBall BigRedBall is offline
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Thanks for your advice once again, Michael.

I take your point about the antenna - I will need to find one with higher gain. However, I don't think I can use a parabolic or yagi antenna as I don't have line-of-sight with the cell tower. Can you or anyone suggest a decent whip or pole-style antenna with gain in the range you suggested, 15-40dB?

  #4  
Old 23-07-2006, 05:35 PM
bodstrup bodstrup is offline
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Antenna Gain

A 15-30 db whip antenna does not exist to the best of my knowledge.

An antenna is a passive amplifier, working by focusing the avaliable energy.

Imagine you have a certain amount of play doe ( :-) ) - that is the energy transmitted from your phone.

The reference antenna, called an 'isotropic antenna', would transmit an equal amount of energy in all directions, giving you a perfect sphere. Range would not be great, but the signal would go in all directions.

A whip antenna gives you a doughnut shaped field of radiation, like squeezing the playdoe ball, making it wider but less high. The whole in the doughnut is equal to the antenna (thus small) and radiation (for a vertical antenna) is transmitted mainly horisontally and decreasing as you go towards vertical.

A long whip gives you a flat and wide doughnut, greatly extending the range, but still covering 360 degrees. That's why a high gain whip antenna is not used to cover many floors of nearby buildings. Only floors at roughly the same level as the whip would get a strong signal.

What you want is probably a maximum of 180 degrees but likely a lot less. To acomplish this, reflectors are used to bounce energy forward in the main direction. A high-gain parabolic disc have just a few degrees of (strong) transmission field, the field resembling a pointed cigar..

You may not have a direct line of sight to the transmisison tower, but the energy that does reach you does come from some direction, perhaps a reflection from a building. If you can get hold of a directional antenna you might be able to find the ideal direction of your antenna and increase both the strength of the received signal and the likelyhood that your signal is registred by the tower.

Sounds like an ambitious project though.

Get some inspiration from a site like the following:

http://www.wpsantennas.com/index.asp...S&Category=159

Regards
Michael

  #5  
Old 24-07-2006, 01:23 AM
BigRedBall BigRedBall is offline
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Thanks again for your advice, Michael. It's extremely useful. I'm learning as I go here and you really seem to know your stuff!

I don't really have the money for a commercial antenna, so I think I'm going to try some home-made solutions, like building a quad sector antenna (possibly with a parabolic dish as well) or a waveguide antenna, using the many WiFi antenna tutorials on the Internet as my guide. Where necessary, I'm going to adapt the dimensions from WiFi's ~2.4Ghz to 2.1Ghz, the frequency of the base station I want to connect to (I might as well go for UMTS reception seeing as it might be a lot of work anyway!).

I will probably blog my findings, so I shall post the link to blog entries here for anyone who is interested.

  #6  
Old 30-07-2006, 11:22 PM
BigRedBall BigRedBall is offline
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Hey guys! I built a biquad antenna - and it works pretty well. Here is my write-up:

Earth: Mostly Harmless :: How I got mobile phone reception where there was no signal :: July :: 2006

I got listed on the Make: blog!

Thanks for all your help, folks!
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  #7  
Old 09-08-2006, 08:51 PM
peab1 peab1 is offline
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I've just installed the CR-47 handsfree holder for the E61 in my Mini and connected the antenna, replacing a previous holder for smaller 6100 pop port Nokia. However, now when the E61 is firmly in the holder it charges but when making a call does not automatically turn the radio off and go through the car speaker system etc, so you can't talk to the other caller. But if I put my old Nokia into the CR-47 it works beautifully.

Could there be a problem with the setup of my E61 which is preventing connection?

What is "Active Diverts" and how do I switch them off if I need to?

There is also an indicator in the top righthand corner of the screen - a tray with an arrow pointing upwards. What does this mean, I can't find it in the manual?

Thanks guys!
 

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