×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

using a cellphone signal booster

using a cellphone signal booster

using a cellphone signal booster

(OP)
I live in the Philippines and am using the zBoost YX-520I cellphone signal booster to boost our GSM and (900 MHz) and DCS (1800 MHz) in our home. The device uses an omni directional dipol aerial (outdoor) antenna and an omnidirectional whip base (indoor) antenna. As we may have all known both of these antennas have a gain of 1 (o dBi). I get a fairly 3-4 bar signal in the house but I want to extend the coverage of the booster. According to its specs the amplifier base unit has a 50dB ADAPTIVE gain and a 100mW RF Output Power. I am planning to "upgrade" both antennae for them to have gains and can probably increase coverage. These are my questions:

1.) The amplifier, being an adaptive kind, has automatic gain control. As I understand with this, the output level of the amplifier (before it is propagated by the indoor antenna) will stay the same (because the amp adjusts the gain for weak or strong signals) as long as the outdoor signal is not extremely low. So I'm wondering if using a Yagi/Log Periodic antenna for the outdoor antenna will increase the total signal gain of the system?

2.) Conversely, would using an indoor antenna with a gain>1 increase coverage?

3.) What does the RF Output Power of 100mW in the specs represent? Does that mean that the power fed to the indoor antenna is always 100mW? I thought that it depends on how strong is the captured signal of the outdoor antenna?

4.) If I upgrade the antennae of the system, impedance matching is very important. How would I know what impedance (50/75 Ohm) would I get in looking for these two antennae? Do I need to test the input and output ports of the amp? How do I know the characteristic impedance of the RG59 cable that I'm currently using if I also decide to replace this with a better coax cable like RG6?

Sorry for all these questions. I'm really interested in getting this done. I'm a licensed Electronics Engineer but haven't quite practiced my profession on antenna signal propagation yet. I learned all of this way back in College but I already forgot most of the concepts. I hope you guys can help me here.

Thank you very much in advance :) Peace!

RE: using a cellphone signal booster

I can only assume that these devices have an installation requirement for a minimum isolation between the two antennas. It says as much in the Setup instructions: "Insufficient distance between the Signal Aerial and the Base Unit." Read the word 'distance' as 'isolation'. You need to keep this in mind.

Your question 3 is answered by your question 1.

RG59 and RG6-type are both 75-ohms and both use (TV type) F-connectors. Upgrading to RG-6 would probably make only a tiny difference (assuming reasonable cable lengths).

You could cover a larger area by installing the system off to one side and using a high gain antenna aimed to the coverage area from one side. The dual band would complicate this.

A corner reflector could be built with cardboard and aluminum foil to provide increase gain (on the order of +10-15 dBi), perhaps even using the supplied whip as the driven element.

RE: using a cellphone signal booster

(OP)
I don't understand how question 3 was answered by question 1. Does that meant that the output is always 100mW as long as the signal outside is high? So what would a high gain signal aerial antenna do for my system?

With your last two phrases above, are you referring to upgrading the base station antenna and increase the gain by using corner reflectors?

RE: using a cellphone signal booster

You state that the relay has AGC, so it's most likely that the output is maintained at a certain level regardless of what the input is doing, down to the relay's detection limit. That makes the most sense, doesn't it? Otherwise, you'd have varying signal inside as a function of varying signal outside, and the whole point of a repeater is to insulate you from variations outside of your control.

TTFN
FAQ731-376: Eng-Tips.com Forum Policies

RE: using a cellphone signal booster

(OP)
Well, does the term "adaptive" mean the same as AGC?

If so, replacing the outside antenna with an antenna with better gain is just useless?

RE: using a cellphone signal booster

(OP)
Yes I am. Why the question?

RE: using a cellphone signal booster

(OP)
BUMP!

RE: using a cellphone signal booster

Thats a small antenna for outdoors and 800 Mhz, so it's probably a simple printed dipole with a backplane.

I would think that a Log Periodic outdoors would do better than this antenna. A yagi is a higher gain Log Periodic and better.
The Yagi is poorly named, Professor Yagi took the credit, but his studendt Uda did all the work. My Antenna professor in 1979 said to spread the word. Taking proper amount of credit won't get you pummelled for decades.

http://www.wpsantennas.com/high-gaindirectionalyag... just some examples.
Make sure it's both bands, tx and rx.

to save money, you could bend some metal (chicken wire) and make a reflector antenna out of your rooftop antenna. Using a Direct TV dish might be a good start (though that's an offset reflector). The wind is a challenge though.

Good luck,

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close