Ask an expert: Aerials, the misunderstood and/or marginalised component?

Ask an expert

Surely the radio aerial, with possibly a signal amplifier present for weaker signals, could be regarded as being the equivalent of vinyl’s cartridge and phono amp stages? If achieved then consequently, we may have more choice and availability of aerials and magazine reviews. Imagine going into a hi-fi shop to discuss an aerial/amp combination that gives a warm sound, or a bassy one? Or best matches a certain tuner?

Should we give more consideration to the electrical/technical spec? And surely it would help if aerials were able to be moved - in direction and length - for best performance? And what about the interconnect, yes, the aerial lead itself? Is it really enough to use a piece of old telly aerial lead you found in the loft? Hardly oxygen-free is it?

Like a cartridge too, an aerial needs alignment. It needs to reject unwanted noise, while being good at pulling in the wanted. And it ought to be maintained for cleanliness to keep performing at its best. As for a signal amplifier, or connecting leads, those could be subjects in themselves.

As it stands, radio is the poor relation in these matters, which commonly go undiscussed.

Ah yes - aerials! What a great subject. I agree with you that the aerial is the source as far as tuners go and like all sources the “rubbish in, rubbish out” maxim applies. To be specific, if the aerial feeds rubbish into the tuner, the tuner will feed rubbish out to the system, being unable to filter it all out. High gain aerials, that is the big ones with many elements (horizontal rods), have high ‘gain’ in the direction of the transmitter, but low gain (good rejection) to all other (off axis) signals. This reduces noise power over the bandwidth of the received signal, as well as rejecting a.m. interference from traffic, off axis transmitters and even DAB interference.

The down lead similarly should be good enough to avoid degrading this signal, by screening out all further interference, since it too can pick up extraneous signals. Good down leads will have low signal loss and effective screening. You can read an interesting observation on the sparse screen braids currently found on cheap cable at www.wrightsaerials.tv/topics/coaxial-cable-screening.shtml.

A good aerial and downlead will, together, feed a strong, clean signal to the tuner. A point to bear in mind is that all VHF/FM tuners need around 1mV per station to go into full quieting (minimum noise) and this is quite a lot of signal. In locations where the transmitter is 20 miles or more away a high gain aerial, often atop a high mast for a clean line of sight to the transmitter, is necessary to get 1mV from the weaker stations. Ideally, a head amplifier will be unnecessary, but it may be a good idea if the cable run is long. A good aerial makes a tuner sound very smooth and deep in its sound staging. It’s an investment well worth making in my experience.

As DAB signals are often weak, a DAB aerial is vital in many locations too, to avoid the nasty breakup sounds described a ‘burbling mud’. DAB aerials are smaller than VHF aerials and mount upright. Sadly, because DAB Mpeg 2 compression is so crude, a technology from the late 1980s, there is less to redeem here, sound quality wise.

Popular amongst hi-fi enthusiasts are high gain aerials from http://ronsmithaerials.com (no www). And finally, for those of you interested in your transmitter, you’ll find a picture of it, possibly on some wind swept hill, at http://tx.mb21.co.uk/. Check out the (desktop) Wallpaper section for some lovely scenic aerial shots, with countryside, snow, moon and what have you in the background. It’s amazing how romantic aerials can be!