Advice Needed Can Anyone Recommend a Group B Aerial

Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
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26,783
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
The aerial can only be tuned at one frequency, which I would assume is mid band (or slightly higher - 700MHz ?).

Only a far more substantial construction than those on sale will have a match anywhere close to 75 Ohms without the associated mismatch, the designs I have seen play about with the spacing between the dipoles, some maufacturers don't even bother deviating from the dimension formula.
 
Markjose

Markjose

Young one with a hobby
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294
My Satellite Setup
Fixed 1.1m 13E and 28.2e motorised 1.1m
My Location
Wokingham
You will receive signal via the back of the log periodic and much stronger than when using an aerial with a reflector, particularly when as in Bracknell, the transmitters are almost perfectly aligned from front to back of aerial. Isn't a problem with most newer tuners, as they can filter channels by transmitter data, selected in the tuning menu. Before the TV software became as selective, I used to have to filter out the "bonus" London channels received via the rear of the aerial to prevent the TV using the first region found as the main channel set and causing breakup.

Interesting.... looking at the polar pattern it doesn't show any gain from behind.

http://www.farnell.com/datasheets/1702913.pdf

Do you have more information to back your theory up as i'm very interested in reading.

Thanks
Mark
 
Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
Staff member
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26,783
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
What you could do is turn the aerial towards Crystal Palace and see if you also receive Hannington on a rescan
 
rolfw

rolfw

Believe it when I see it Admin.
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37,798
My Satellite Setup
Technomate 5402 HD M2 Ci, DM7000s, Transparent 80cm Dish, Moteck SG2100 DiseqC motor, lots of legacy gear. Meters: Satlook Digital NIT, Promax HD Ranger+ spectrum analyser.
My Location
Berkshire
Interesting.... looking at the polar pattern it doesn't show any gain from behind.

http://www.farnell.com/datasheets/1702913.pdf

Do you have more information to back your theory up as i'm very interested in reading.

Thanks
Mark
It's not theory, just what I know to be the case. I fit these and other types of aerial regularly and even aerials with reflectors will allow some reception from the back or side. Because it has no theoretic gain from the rear doesn't mean that it won't receive a signal, just that the aerial won't amplify it, so given that the Crystal Palace transmitter throws out a lot of signal and Bracknell is well within the reach of the footprint, you are likely to receive usable signal on some multiplexes.

If you turn it round and point to Crystal Palace, you are bound to receive a partly usable signal from Hannington.
 
Last edited:
Markjose

Markjose

Young one with a hobby
Messages
294
My Satellite Setup
Fixed 1.1m 13E and 28.2e motorised 1.1m
My Location
Wokingham
Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
26,783
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
You don't have to disrupt the - highest quality - install already in place for this experimentation.:cool:

Where have you fitted the log periodic by the way ?
 
Markjose

Markjose

Young one with a hobby
Messages
294
My Satellite Setup
Fixed 1.1m 13E and 28.2e motorised 1.1m
My Location
Wokingham
You don't have to disrupt the - highest quality - install already in place for this experimentation.:cool:

Where have you fitted the log periodic by the way ?
On the hotbird mount pointing just below the CP Antenna.

Seems to be working pretty well, Positioned the antenna behind the dish so the antenna works as a wind break.
 
Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
26,783
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
On the hotbird mount pointing just below the CP Antenna.

Seems to be working pretty well, Positioned the antenna behind the dish so the antenna works as a wind break.

In light of the absence of any other wind break up nearby.

What about the cell towers, do you turn them off when you go outside, wrap yourself in foil (or pay somebody else to be irradiated ?)
 
Markjose

Markjose

Young one with a hobby
Messages
294
My Satellite Setup
Fixed 1.1m 13E and 28.2e motorised 1.1m
My Location
Wokingham
In light of the absence of any other wind break up nearby.

What about the cell towers, do you turn them off when you go outside, wrap yourself in foil (or pay somebody else to be irradiated ?)
No Cell Tower on the roof yet ;) No plans either.
 
RustySpoons

RustySpoons

Sleepy Hollow
Messages
2,207
My Satellite Setup
50E - 30W
CM 1.2m Polar Mount/Jack
65E- 65W
Gibertini 1m OP100 - STAB HH100 - Inverto Black Ultra 0.2 Twin
Mutant HD51
Edision Primo IP S2
Dreambox DM800HD
Venton Unibox HD2
Sony Bravia 50W829 DVB-S2 Tuner
My Location
South Wales
Log Periodic:
 
Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
26,783
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
I installed a log periodic earlier today (Antiference LP28F) and the specifications are for an almost level gain between Channels 21 - 68, no more than 1/2 dB over the whole range.

Front / back ratio is 27dB (frequency not specified) which I assume to be the difference in signal if the antenna was turned 180 degrees around
 
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