FM e cellulari, l'antenna è "embedded"

Da tempo la lobby degli editori radiofonici americani, National Association of Broadcasters, preme perché venga approvata una normativa che obblighi i costruttori di telefonini a integrare a bordo dei cellulari la ricezione in FM, in modo da contrastare, sfruttando la grande diffusione dei telefoni mobili, la tendenza degli ascoltatori, soprattutto giovani, ad abbandonare la radio a favore di Internet e della musica mp3. Una proposta molto controversa, come sempre succede negli Stati Uniti quando si sente parlare di intervento del legislatore. Le perplessità sono tanto più forti in chi obietta che diversi telefonini hanno già l'FM a bordo e che i consumatori possono sempre scegliere se acquistare quelli o modelli con meno features a bordo e quindi un po' meno costosi.

Domani a Washington il NAB apre il suo Radioshow e la newsletter TechCheck pubblica una interessante anticipazione dedicata proprio ad alcuni modelli, in particolare Nokia e Motorola, con radio analogica integrata, che saranno oggetto di un apposito stand alla manifestazione. E' l'occasione per TechCheck di parlare del problema antenna. Tra cellulari e lettori MP3, i piccoli dispositivi mobili con chip FM integrato non mancano sul mercato dell'elettronica digitale e quasi invariabilmente tutti risolvono il problema delle dimensioni dell'antenna ricevente ricorrendo al filo dell'auricolare, una soluzione abbastanza pratica ma non del tutto ottimale, specie là dove l'ascolto viene effettuato con cuffie Bluetooth.

TechCheck cita invece alcuni costruttori che stanno sviluppando interessanti antenne attive integrate, come i chip in silicio, a bordo di piccole schedine PCB, affarini di poche decine di millimetri di lato come si può vedere in questa brochure di Antenova. A bordo di questi chip solenoidi e induttanze e l'elettronica di controllo per variarne le dimensioni "elettriche". Sono le cosiddette antenne "embedded". Molto interessante. I nomi delle aziende citate sono, oltre Antenova, la Ethertronics (entrambe americane) e la britannica The Technology Partnership.

Radio-Ready Cell Phone Showcase at the Radio Show

Including radio functionality in a cellular phone is easily done, and in fact hundreds of millions of cell phones have been made with FM radio (sold mostly outside of the U.S.). At this week’s Radio Show (September 29–October 1, 2010, Washington, D.C. www.radioshowweb.com), an exhibit in the lobby will highlight this fact and include examples of phones that have radio functionality, as well as information on devices which facilitate easy and affordable inclusion of embedded FM radio antennas.

The Radio-Ready Cell Phone Showcase will be located on the Constitution level of the Grand Hyatt, right next to the escalator leading down to the Renaissance level, which is where the Radio Show Marketplace and session rooms are located.Phones on display with FM radio will include the Nokia 5030 and the Motorola ROKR EM35 (shown in the photos at right) as well as phones from Samsung and Sony Ericsson.

The primary components needed to include an FM radio in a cell phone include a tiny FM receiver integrated circuit (IC) or “chip” (which typically measures about 3mm on a side) and an FM antenna.FM receiver functionality is also often incorporated into the ICs that many cell phones already have for supporting wireless Bluetooth and WiFi capabilities, and in these instances the only additional requirement to make these phones FM-capable would be the inclusion of the FM antenna (plus some additional software for providing a user interface to the radio feature).

In most current phones with FM radio, the headset cord that is used for listening to the audio also doubles as the FM antenna, however a more elegant solution is to embed the antenna within the case of the cell phone itself. Both the Nokia 5030 and the Motorola ROKR EM35 have embedded FM antennas. However, neither of these GSM phones is currently offered by any U.S. cellular carrier.

Three embedded antenna manufacturers – Antenova (Cambridge, U.K., www.antenova.com), Ethertronics (San Diego, Calif., www.ethertronics.com), and The Technology Partnership (TTP, Melbourn, U.K., www.ttp.com) – will have posters and literature at The Radio-Ready Cell Phone Showcase describing their embedded antenna technology. Two of these vendors (TTP and Ethertronics) are currently developing advanced embedded antenna designs for handheld FM radio and mobile DTV (low-and high-VHF and UHF frequencies) applications with funding from the NAB FASTROAD technology advocacy program (www.nabfastroad.org). At the Showcase, Antenova and Ethertronics are highlighting the following off-the-shelf antenna products:

Antenova’s M10385 module is an active antenna module consisting of Antenova’s patent pending FM antenna with a matching circuit and low noise amplifier (noise figure of 1.5 dB) in a small, 30 x 5 mm package. The module may be surface mounted on the cell phone host printed circuit board.

Ethertronics’ Tavvel FM-p10 antenna consists of a small (3.5 x 6.1 mm) surface-mountable module and a tuning coil element.This tunable antenna (with a passband of 600 kHz, tuned over the 88-108 MHz FM band) uses a single control line to tune the antenna via pre-set control voltages.