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Appendix

Where I put stuff when I can`t think of anywhere else to put it.......

Appendix Index

UHF Channel Numbers to Frequency etc

UHF frequency wavelengths

FM/DAB results

Polar Response Diagrams

Test results (full) of Group A aerials

Test results (full) of Group B aerials

Test results (full) of Group C/D aerials

Test results (full) of Group K aerials

Test results (full) of Group E aerials

Test results (full) of Wideband aerials

Test results (full) of all the grouped aerials

UHF Channel Numbers

In the UK television transmissions are usually referred to by a channel number as opposed

to a frequency. Both the channel number and the frequency are given on all our Channel

Allocation Guides (e.g. the one for Crystal Palace) but the frequencies are rounded down

by 0.25MHz. For example the exact frequency for CH21 is 471.25MHz.

The table below also shows channel number v frequency (and also the wavelengths).

In the case of analogue the channel number is related to the frequency thus :           

                                  Fv = 8n + 303.25

Where Fv = Frequency of the vision carrier in MHz and n = Channel Number.

For digital the channel number is related to the frequency thus :                    

                                   Fc = 8n + 306

Where Fc = Centre frequency of the MUX,  and n = Channel Number.

As an approximation, good enough for most tuners, the digital frequencies are 3MHz

higher than the analogue (although it`s actually 306 - 303.25 = 2.75MHz).

Since most tuners use channel numbers this 3MHz difference is not usually significant, but if you are trying to enter the actual frequency to yours it obviously might be for you !

Some digital MUXES are transmitted with a channel offset and these are + or - 0.167 MHz.

These offset frequencies can be found in the relevant Ofcom documents :

                             for pre DSO                             for post DSO.

The vast majority of digital TVs or STBs can still tune in to a MUX even if it has an offset

and this is also the case in manual tuning. If you have trouble trying to tune in your

MUXES its always worth checking that the tuner is not being sidelined by an offset, though

this should be very rare.

Such is the Black Art nature of RF all aerial test readings are approximate, in fact

as far as I`m aware

no lab will guarantee accuracy better than +/- 0.5dB.

It must be admitted that these particular results are less accurate than that (unlike our TV aerial tests) but they still give a pretty reliable indication of the relative performance of the various antennas.

UHF TV frequency wavelengths

To calculate the wavelength (in cms) divide 30,000 by the frequency (in MHz).

This should be accurate to 0.07%, which is accurate enough for most RF applications....

The “variable” figures result from the directional nature of the particular aerial.

This doesn`t apply to the TV aerials, they`re variable because they`re not even designed to

pick up VHF frequencies !  Note that if the 3 element aerials were pointing directly away

from the transmitter you`d probably lose more than the - 5dB quoted for the FM3.

Though you would be pretty unlucky if you were to align your aerial like that  !

Typical Polar Response Diagrams

Log Periodic Polar Response

Typical 10 Element Wideband Yagi Polar Response

XB14 A Group Polar Response

XB14 Wideband Polar Response

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