The 900 MHz Band Plan provides for Low Capacity Two Frequency (LCTF) point-to-point fixed links in the paired frequency bands 854-857 MHz and 930-933 MHz. The planning arrangements and assignment and licensing guidelines for LCTF services are contained in Spectrum Planning and Policy Document 06/93 (PDF 452kb). The LCTF channeling arrangements are based on provision of 50, 100 or 200 kHz channels. LCTF planning has also been based upon use of notional 2 metre grid-pack antennas.
In January 2003 a Survey (PDF 116kb) of use of sub-notional antennas and application of Advisory Note AW in the 854-857/930-933 MHz bands was undertaken. It found that in about 75% of cases notional antennas, or better, were being used. It was also found that in cases where sub-notional antennas had been approved they were mainly sub-notional by only a small amount (a few dB if gain is taken as the basis for the assessment). However a small percentage of approved sub-notional antennas had performance that was significantly below that of the notional antenna. The study also showed that in about half the cases where sub-notional antennas had been approved the Advisory Note AW which states "The licensee may be required to replace the antenna with another having higher performance in order to facilitate efficient spectrum usage" had not been applied.
As an outcome of the survey Supplementary advice (PDF 15kb) to assigners concerning use of sub-notional antennas and application of Advisory Note AW in the 854-857/930-933 MHz bands has been produced. This should assist assigners by providing clearer guidance about how the notional antenna guideline should be applied. This should help to achieve and maintain more consistent assignment practices in this band.