Hi Diego, first of all I'm not an expert on antennas, so this is afaik. RF waves are made of two fields, electric and magnetic. Electric field won't pass through metal, this actually means that most of its energy will be reflected, though a little part might. This depends on how thick the metal is and other properties of the material and you will have to test if its enough for you (given a strong signal) but it's not a good practice at all. Magnetic field in the other hand will pass through metal, though there are special antennas to capture each field (typical monopole/dipole antennas are used for the electric field, and those with a loop made of conductor for the magnetic). I don't know if there are magnetic field antennas for those technologies. Also, you might find special antennas to put outside the case which aren't easily removed, just wondering. Hope this is right and helps! and double-check what I'm saying anyway!
Place an antenna inside a metal case. There are some difficulties,Because The signal strength will decreases!
You can call E-lins technology(szelins.com) for details! They are antenna Expert!
Diego, inside a standard metal case your GSM and GPS module will receive nothing. What about to read the M2M IoT Cookbook?
April 2014 @ M2M Journal http://www.m2m-alliance.com/fileadmin/user_upload/pdf/m2mJournal/140402_M2M_Journal_low.pdf
The example of a locating device based on cellular modules (GSM, HSPA, LTE) and GNSS modules (GPS, Glonass, All Galileo) explains how to develop a complex IoT / M2M-device with embedded antennas. The person, who has to develop a telemetry device, ignores the part of GNSS. The 20 years of experience in the development and consulting wireless devices is included in all chapters. The integration of antennas has been paid special attention. The antenna is the key to success with any wireless application. The simulation, and the result, is a quad-band GSM antenna and is explained in detail.
Each developer can easily copy the result without the use of mathematics. In the example of the vending machine, the self-made, integrated antenna not only saves the external antenna, but also the coaxial socket and installation as well. The same antenna can save the expensive SMT mount cellular chip antenna in a locating device and is easily adapted to the Epsilon R of the housing. Other sub-themes are power supply and choice of carrier (USSD, SMS, CSD, DTMF, GPRS) approvals. Typical mistakes of first-time users are addressed too.
The developer selects the antenna design first and then builds the device around the antenna. This results in a large cost saving for hardware and installation. At the vending project the estimated saving was 4,000 installations x $ 10 = $ 40,000. The integrated antenna with the optimised ground plane is so good that during redesign the switch and the coaxial socket to the external antenna were excluded.
ABOUT THE AUTHOR HARALD NAUMANN
More than 25 years in radio communication with a focus on wireless data communication. Today he is working with Future Electronics as a Field Application Engineer for wireless applications.
Harald Naumann • Field Application Engineer for wireless applications •
harald.naumann(at)gsm-modem.de • www.gsm-modem.de/M2M/m2m_iot_cookbook/
Origin text with photo: http://www.m2m-alliance.com/fileadmin/user_upload/pdf/m2mJournal/140402_M2M_Journal_low.pdf
Many thanks again to the M2M Journal team for printing the abstract.
Do not hesiate to ask for a copy of the IoT M2M Cookbook.