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Best Loft Aerial?

 
 

What's the best Indoor aerial or outdoor aerial for home or caravan? Best Loft Aerial?

Aerials designed for indoor use are generally poor performers

Aerials designed for indoor use are generally poor performers because they are small and have few "elements". Size matters - don't let anyone tell you that it doesn't! Most "indoor aerials" have little or no gain but manufacturers try to hide this fact by incorporating a "high-gain booster" then boasting that the aerial has, say, "a twenty dB gain" when in fact it has nothing of the sort. The booster gets the signal above the threshold of the digital tuner but it's a very noisy signal which (if it gets a picture at all) is likely to suffer from "dropout" and "freezing".

This type of aerial with unsupported reflector stubs is useful only as a loft aerial. It is easily bent by birds and wind, so I don't recommend it for outdoor use unless it is a type that has a strong supporting frame or a mesh design.

Note that this one is very short so, despite possible claims to the contrary, it has a very low gain and is useful only in a strong signal area. Length is most important.


Links to items on this page: Vision "Focus" V10-040 on a shed. Vision "Focus" V10-040 through a window. The shorter V10-030 aerial. Notes on indoor and loft aerials. Booster. Aerial comparison graph. Advantages of a Log-P Gable end aerial kit. Loft aerial kit. Caravan owners

THERE'S NO SUCH THING AS A "DIGITAL AERIAL"!
See
http://www.paras.org.uk

Dear Martin,

I'm self employed and work from home in Crewe doing electrical wiring and repairing electronic equipment - mostly TV sets. I use a large garden shed as my workshop and a 12 foot pole supports my minidish and TV aerial. Until recently I was using a Unix 52 aerial to give me a signal for testing TVs and Freeview receivers. Because we are surrounded by tall buildings the signal is terrible and analogue pictures were full of "ghosts" caused by the reflections. I added a masthead amplifier but that didn't help and I was convinced that the aerial system was as good as I could achieve.

Then I read about your Vision "Focus" V10-040 log-periodic aerial and, although I was sceptical, decided to give it a go. The results are nothing short of amazing! Analogue pictures are now crystal clear and Freeview pictures no longer suffer intermittent pixelation.

I attach a couple of photos to show you my set up. Thanks!

Terry Boyd, Tardis Electronics, Crewe.
17 May 2008

The Vision

The Vision "Focus" V10-040 log-periodic in place.

It has no reflector and is not easily damaged by birds or wind.

The Unix 52 - relegated to the scrap pile!

The Unix 52 - relegated to the scrap pile!

Vision

This Vision "Focus" V10-040 log-periodic aerial at only £15.75 is about 1.3 metres long and 0.3m wide but takes up very little vertical space because it has no reflector screen. It is exceptionally resistant* to "impulse noise" from road vehicles and house wiring, making it ideal for installing in your loft or bedroom or on top of your wardrobe.

If you are sick of "pops", "cracks" and "picture freeze" caused by impulse noise, this aerial could be your answer. It's the best "loft aerial" we've found - even though it wasn't designed as a "loft aerial"!

It's one of those well-kept "trade secrets" which only professionals know about. But now you do, too!

Order this Vision "Focus" V10-040 and solve your reception problems.

Aerial alignment meter

DTV Digital Terrestrial aerial signal meter for Freeview.

Aerial alignment meter.

More info.

Note: The log-perodic aerial is inherently "wideband". As transmissions will be stronger, and with more transmitter areas overlapping, once analogue is switched off, it may be necessary to cut out unwanted signals by fitting a band filter. If multiplexes are swapped to different frequencies in the future, it will then be much easier to remove (or swap) the filter than to change the aerial (as would be required if a "grouped Yagi" aerial were fitted). For this reason, plus the others mentioned on this page, we strongly recommend installing a log-periodic aerial (with filter if required) wherever possible.

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Aerial upgrade kit

Suitable for digital Freeview in most UK locations.

The closest you'll get to a true "digital" aerial.

Gable-End aerial kit looks similar to this
Gable-End kit looks similar to this

 

*Bracket and bolts not supplied in chimney kit.

To mount aerial on a chimney, please order a separate chimney mounting kit with bracket(s) as well. (You must not drill a chimney.)

If you need additional cable or parts, please add them to your cart, separately.

 

Complete gable-end kit comprising:-

  • 40 element log-periodic aerial
  • Aluminium pole 6' x 1.25" diameter
  • Galvanised steel wall bracket 12" x 12"*
  • 2 x U bolts
  • 4 x wall bolts*
  • 15 metres WF100 cable (choose colour)
  • 10 x cable ties
  • 100 brown cable clips with nails
  • 3 x TV plugs
  • 5 x WF1 'F' plugs
  • 1 x male-female adapter
  • 1 x silicone grease
  • Optional 4-way adjustable-gain masthead amp (with power supply to plug in near TV)

AERKIT1 "Focus" V10-040 complete gable-end kit £39.99

Straight pole 6' Cranked pole 6'

Include 4-way Masthead Amp with PSU £19.95


Below: For chimney mounting (please order a separate mounting kit with bracket(s) as well).

AERKIT6 "Focus" V10-040 complete gable-end kit £37.99
Bracket not supplied.

Straight pole 6' Cranked pole 6'

Include 4-way Masthead Amp with PSU £19.95

Aerial upgrade kit

suitable for digital Freeview in most UK locations. For loft or room mounting.

Aerial upgrade kit in loft

Horizontal or vertical mounting.
Pole can be screwed into loft rafter or suspended from ceiling rafter in a room.
Or aerial may be put on top of a cupboard.

Complete LOFT kit comprising:-

  • 40 element log-periodic aerial
  • Loft spike (mounting tube)
  • 15 metres WF100 cable (choose colour)
  • 100 brown cable clips with nails
  • 3 x TV plugs
  • 5 x WF1 'F' plugs
  • 1 x male-female adapter
  • 1 x silicone grease
  • Optional 4-way adjustable-gain masthead amp (with power supply to plug in near TV)

AERKIT2 "Focus" V10-040 complete loft/room kit £29.95

Include 4-way Masthead Amp with PSU £19.95

We are getting a lot of questions about this so we've asked the manufacturer for clarification.

It appears that, in order to get rid of impulse noise effectively, the aerial bracket must be "grounded". If you suffer from impulse noise problems in the loft, we suggest that the aerial be clamped to an 18 inch "spike" (see below) and that the spike be screwed through a large area of aluminium foil to form a ground plane. An alternative might be to connect the aerial clamp to a cold water copper pipe using copper wire. Any such grounding arrangements should be kept well away from mains wiring.

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The Vision "Focus" V10-040 has 40 elements. Unless you know you are in a strong signal area, this is the one to use. Very popular with narrow boat and motor home owners!

Accessories

Vision V20-1127 amplifier

If an additional boost is required, our Vision V20-1127 amplifier gives adjustable gain between 12 and 20 dB, which is adequate for most installations. Ideal for long cable runs or "deaf" receivers. Preferably fitted close to aerial (for best results - but may be used further away if there's absolutely no alternative) and powered by its own separate 5 volt power unit which can be located downstairs.

Also available with 1, 2 or 4 outputs so that you can feed cables to several rooms without signal loss.


the Vision

For difficult locations, read about the Vision "Duo" V10-stealth Log-periodic wideband aerial array.

Click Here


Indoor Aerials

Note: indoor aerials are notorious for causing problems because the signals can be reflected by nearby walls, roof tiles, pipes, wiring and even human bodies! The result can be signal cancellation, causing complete or partial loss of some channels. The positioning of the aerial can, therefore, be extremely critical. Even after you've got it "right", if something gets moved (even a metal object next door) the signal could be affected.

In general, aerials should be mounted as far from the TV set as possible because TVs radiate interference. Obviously the last place you want a receiving antenna is next to a transmitter of interference! For the same reason, the cable from the aerial to the TV should be double-screened.

Because of signal reflections and interference, the positioning of an indoor aerial is absolutely critical. An inch can make the difference between receiving all channels perfectly or none. (Each time you move the aerial you must rescan the channels until you have them all. After that do not rescan!) I'd start by keeping the aerial as far from sources of interference as possible. The major source of interference is the TV set itself. (How many times have you seen an aerial perched on top of the TV and "wavy lines" on the picture?) Other sources of interference include electrical wiring and electrical equipment - especially equipment fitted with a thermostat. So don't do the ironing next to the aerial!

If you think you have problems of interference, move the Freeview receiver away from the TV set (a source of interference) and switch off all other equipment in the house, including TV sets, DVD players, fluorescent and energy-saver lights, computers and central heating.

Placing the aerial on top of (or above) a metal structure can sometimes help. Try a metal CD rack or a (cold) radiator. Try varying the height. In a bedroom, on top of a wardrobe is often a good choice.

The best place for an aerial indoors is usually in front of a window which faces the direction of the desired transmitter.

the aerial may be fixed directly to a ceiling with a couple of thin metal straps

As an alternative, the aerial may be fixed directly to a ceiling with a couple of thin metal straps with holes in both ends. Make a wooden frame and screw that to the ceiling. Fit LED strings around the frame. Make sure the aerial works (with the lights switched on) then finish by screwing a square of plywood to the frame. Make it overlap the lights. Paint it to match the ceiling (or as desired).

The cables can run above the ceiling or in plastic trunking.

Note: fluorescent tubes will create a lot of interference so use LED lamps.

Is your Freeview receiver a good one? (Many cheap modern ones have very poor tuners that require a strong aerial signal. You can waste a lot of money on aerial systems when it's your cheap supermarket receiver that's at fault!)


Loft Aerials

A Loft Spike

A Loft Spike can be used to support the aerial in the loft or suspend it from a ceiling.

Loft aerials can be troublesome because they are so close to house wiring, human bodies in the bedroom, water tank (reflections), roof (attenuates signal - especially when wet). Make sure that the roof is not lined with a reflective metallic layer! Arrange the aerial so it is pointing through tiles, not bricks. The centre of the loft is often the worst position for interference. Try to place the aerial away from the centre.

Make sure that cable is fully shielded type and does not run parallel to any mains cables. If the aerial itself is picking up interference then you might be able to shield it with a "ground plane" at least 0.5m below it. However, the chances of success are small. If the cable is picking up interference then try amplifying the signal from the aerial with a very low-noise masthead amplifier and attenuating it at each receiver. This will have the effect of minimising any unwanted interference picked up by poor quality cable. (Of course the best cure is to replace the cable with the proper stuff - WF100 or similar.)

If the signal is very strong, you may need to use a passive splitter (not amplified) and maybe even fit an attenuator at each receiver if the signal reading is still high.


as soon as I took the aerial into the bedroom and pointed it through the window glass, the signal was perfect!

I had no success with this Vision "Focus" V10-040 log-periodic aerial in my loft. Clearly my roof must have some material which attenuates the signal.

However, as soon as I took the aerial into the bedroom and pointed it through the window glass, the signal was perfect! Even the houses, opposite, didn't appear to degrade the signal.

Opening the window and sticking the aerial outside (see photo) made no apparent difference, so the double-glazing window glass was obviously having no discernible effect.

I'm 33 miles from Winter Hill transmitter and the "Wolfbane" predictor gives 36 dBuV/m signal and suggests an "amplified extra hi-gain CD" aerial. Wrong! This is a low-gain log-P without an amplifier. Perfect results!


miniature TV set

This is the miniature TV set which I use for quick aerial alignment. The screen displays in black and white but that's adequate and it cost me only £24 off eBay!

It's also my "sniffer" for locating sources of interference.

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Aerial Gain

All aerials have an effective "gain" or "amplification factor". This is normally compared with a "dot in space" and the unit of measurement is the "dBi" (decibel isotropic). A more realistic measurement indicates how much more gain the aerial has than a simple "dipole" aerial and the measurement is the "dBd" (decibel dipole). You'll find most web sites quote "dBi" because it is 2.15 greater than "dBd" so it looks better!

A log-periodic aerial is made from a row of dipoles connected together. Each dipole is tuned for a slightly different frequency, making the gain of the aerial almost constant across the UHF band from channel 21 to 69. It is inherently "wideband".

A "Yagi" aerial has one dipole, a reflector, and a number of director elements which, in combination, make the aerial directional and help to reduce the pickup of signals from the sides and behind. However, a log-periodic aerial is inherently very directional and ignores signals from behind and to the side. It is said to have very small "side lobes". A Yagi is inherently a "narrowband" aerial but it can be designed to spread its gain across much of the UHF band, with some "droop" at the top end and even more at the lower end of the UHF band. See typical graph, below.

Aerial Gain comparison

You can see that the log-periodic typically has a gain of less than 9 dBd whereas a good wideband Yagi can have a gain as high as 13.5 dBd around channel 57, falling away drastically towards the lower end of the UHF band.

In some cases a wideband Yagi will be a good choice if your transmitter provides channels between, say, 40 and 69. However, if your transmitter uses channels 21 to 37 (Group "A") then a Group A aerial would work better, since its gain is concentrated there. Indeed, a log-periodic would probably work at least as well as a wideband Yagi for Group A transmissions.

Although a log-periodic has a relatively low gain, it is more immune to picking up impulse interference and unwanted signals from other transmitters. This fact means that it's possible to amplify the signal from a log-periodic more than from a Yagi, without causing problems. A Log-periodic will often give surprisingly good results, compared with a wideband Yagi. It's also smaller and has less wind resistance than a Yagi. It's estimated that a log-periodic aerial would be suitable for around 85% of installations in the UK.

Q. Can a log-periodic be used for a "group A" transmitter?

A. A log-periodic is a true "wideband" aerial, which makes it suitable for use anywhere (unlike a so-called "wideband" Yagi whose gain falls off drastically at lower frequencies.) However, if there's a risk of interference from other transmitters, it's possible to connect a "group A" filter so that only the lower frequency signals are passed.

For more Freeview help click HERE


The coaxial cable is fed up the lower tube to the front of the aerial

The V10-040 uses a printed circuit board with soldered sockets. The coaxial cable is fed up the lower tube to the front of the aerial and an 'F' connector is fitted. This is screwed to the socket then the assembly is pressed into the square-section tubes so that the sharp corners of the sockets bite in and make a firm connection. All connecting parts should be coated with silicone grease before fitting. This will keep moisture at bay and help prevent corrision.

silicone grease tube

For long-term reliability of ANY outdoor aerial, we recommend that you remove the plastic caps, give all connections a generous helping of silicone grease, then replace the plastic caps. This should greatly reduce the risk of corrosion.

silicone grease syringe

Read our complete log-periodic assembly instructions HERE.


What are the advantages of a log-periodic aerial?

What are the advantages of a log-periodic aerial?

  • Good immunity to interference
  • Low wind resistance
  • Low profile - inauspicious
  • Low weight and size - easy to install
  • Robust construction
  • Wideband
  • Ideal for analogue and digital reception

Will I need a masthead amplifier?

If you are in a weak signal area and have a long cable run, or if you are in a medium signal area and wish to split the signal.

Where can I use the aerial?

  • Indoors
  • Outdoors
  • Caravan/Motor home/Narrow boat etc.

If you are looking for a Caravan Aerial, please read the report HERE.

 

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©2006-2011 SatCure

The Freeview Bible eBook

Piping TV around the house

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