What is a Log Periodic Aerial?

We are often asked “What is a Log Periodic Aerial?” and “Should I be using a Log Periodic Aerial?”

Log periodic aerials are used for the reception of Digital Terrestrial TV services such as Freeview

As you can see from the image they look slightly different to a conventional ‘old style’ TV aerial with the rear reflectors that we often see on top of chimneys. One customer once described them to looking like a fishbone. Don’t be put off as a Log Periodic can perform just as well if not better then a Yagi style TV aerial.

A Log Periodic TV aerial offers many benefits over traditional wideband TV aerials. Most notably, you’ll get more consistent signal levels across all Freeview multiplexes, as Log Periodic aerials have a flat signal gain characteristic. This means they work equally well on all UHF TV channels – making them truly “wideband”. By contrast, most wideband “yagi” antennas work less well on the lower Group A UHF channels.

Triax Log Periodics are well built and resistant to element damage, making them ideal for caravan or boat installation where the antenna is frequently taken down and equally suitable for home installation in a loft or outdoors.

A Log Periodic TV aerial is perfect for digital reception as it rejects impulse noise much better than a traditional Yagi aerial. Impulse noise is the largest cause of picture freezing and signal dropout on Freeview reception. Logs also offer much improved rejection of unwanted signals from other transmitters eminating from the back or side of the aerial – due to the Log Periodic’s tight polar diagram.

A good quality log periodic like the Triax TL 28F, will work well on all UK TV channels and be suitable for use on all main and relay TV transmitters in the UK. It is light and easy to install in a loft space or outdoors and can be mounted with vertical or horizontal polarisation.

As there is no large reflector, the wind loading on a Log Periodic aerial is much less than with a traditional Yagi TV aerial, so the aerial can often be mounted on a longer pole leading to much better results than much larger more visually obtrusive aerials. This often amply makes up for the fact that the Triax TL 28F has slightly lower signal gain on the Group B and Group C/D UHF channels than a conventional Yagi-type wideband aerial.

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