UHF is the frequency chosen by Wal-Mart, some other retailers, the US Military, the tire companies and the airlines/ airports for passive RFID labeling and there is some move in Japan and Korea to make UHF the basis of buying things with your cellphone, though no certainty as yet. (the global "NFC" standard for mobile phones is at HF). Unfortunately, UHF will never be one frequency because military and mobile phone companies have got there first, so different countries have radio regulations permitting various parts of a band of about 100 MHz. Within their permitted part, the Europeans typically choose around 868MHz, the US around 915MHz and so on. China and some others have chosen a very narrow bandwidth which also causes problems. RFID label antennas do not usually work at all the frequencies - different ones often need to be printed.
Although most UHF passive tag suppliers lose money, some spectacularly so, several are in it for the long haul and they continue to improve their products.
Checkpoint Systems announced earlier this year the development of several new EPC Generation 2 UHF RFID labels and tags with printed silver antennas. They are designed for broad-band (860-960 MHz) case and pallet applications in the retail supply chain. Checkpoint partnered with Texas Instruments to develop two of the new designs. Combining Checkpoint's attachment process for CheckSi straps with EPC Gen 2 UHF silicon from TI and UHF market leader Impinj, the new family labels and tags were designed to operate across multiple frequencies within the UHF range. Checkpoint's manufacturing platform allows the CheckSi strap to be attached at high speed to various antenna designs without modifications to the strap. The strap itself can be used with most Gen 2 chips available today, is designed to be 'converting friendly'. It can be attached to many antenna designs. The new labels and tags are available in 2x4 inch, 4x4 inch, and 4x6 inch labels, as well as in wet and dry inlay formats.
There are indeed many antenna designs at UHF because optimizing the performance calls for a special antenna for each family of applications and some customers buy the cheapest while others buy the best. There is no agreement about the optimum antenna for a given application and price. Some of the current designs are shown below. Most employ printed silver antennas using inks such as Parelec Parmod™.
Potential for UHF RFID antennas attached to silicon chips in RFID labels is about 50 billion yearly - the chip cost limiting greater sales - and potential for all types of RFID when both logic and antennas or equivalent are printed is trillions yearly. For more read RFID Forecasts, Players & Opportunities 2007-2017. RFID is also being developed in printed form without logic and often without antennas for the highest volume applications, where the tag will often be printed direct like 85% of barcodes today, no label being needed. Vubiq, Inksure, Somark Innovations and new entry (under license) Marubeni - announced this week at the successful IDTechEx conference Printed Electronics Asia in Tokyo - are in this game. See Printed and Chipless RFID Forecasts, Technologies & Players 2007-2017. The largest application of RFID in numbers of tags may be eventually be food, though RFID cards, animal tagging and even RFID pages for passports and active tagging for military forces are far bigger markets by value at present. Read RFID for Animals, Food & Farming 2007-2017.