...and another newbie...

[JusNoGood]

Welcome Chris. I’m from Surrey, Reigate just up the road from you. I whizz down past Pulborough to see kin all the time. I have a silver 1989/1996 SE

[chrism]

Thanks Saltire...I think...
And JusNoGood we'll have to compare 'bits' one day...oo'er...

[dapinky]

And JusNoGood we'll have to compare 'bits' one day...oo'er...

No offence intended to either of you - it's just that those who have been here a while (or ever seen Justins' car!) will know that trying to find anything on it which resembles something fitted to more than 20% of other cars takes a lot of looking for!

That is the "advantage" of owning a Lotus development car which they used for every model and market 'testing' at the factory before flogging it off.

(But Justin is a really great helpful guy who will be happy to chat and drink your tea).

[chrism]

well I'm sure he's very nice anyway...

[GeoffSmith]

DAB is only vertically polarised.
Any metalwork (unlike fibreglass, which is almost transparent to RF) will interfere so a semi-vertical antenna mounted close to the A post pillar will tend to be directional both due to the angle and also because of the earthed pillar acting as a screen/reflector.

[chrism]

Hi GeoffSmith. Thanks for the reply. Good to know for sure that DAB's vertical.

Furrowed brow here doesn't the DAB w/screen sticky have a coppery sticky connector that's necessary to stick to the metallic windscreen and act as a ground plane (ie effectively being the other half of the dipole by 'reflection'?) or have I got it wrong?

I was fascinated by one of your earlier posts about a dipole stuck under the boot lid (but it seemed to go off on a tangent with boot hinge levers, I think) and this could be an alternative for fibreglass-ers like us? I'm thinking your solution was for am/fm tho'(?) but I might be wrong...you gave a length (and I'm going back to find it asap : I think I need to bone up on aerial technology...)

Another furrowed brow moment: You mention 'a semi-vertical antenna mounted close to the A post pillar will tend to be directional both due to the angle and also because of the earthed pillar acting as a screen/reflector.' Sorry not really understanding; are you meaning a 45degree sticky/aerial? And what do you mean by 'will be directional'? (does that mean 'will receive a signal'?)

And does the sticky coppery bit need to touch the earthed pillar to provide moving charges hence magnetic induction, hence a 'reflection'...but the w/screen pillar is vertical... ...so shouldn't the sticky/aerial be vertical, too?

Sorry, not meaning to be challenging but I'd like to understand how to get the best DAB/DAB+ reception for myself and others that might have 'furrowed brows' too.

[Blaster]

Here is a picture of the Bosch DAB aerial in the standard M100 position.

[chrism]

Yep that looks really neat; it's a vast improvement on all those aerials at crazy angles...but I bet that mast is unobtainable now?

Tbh I think I'd prefer to exhaust the boot-mounted option first 'cos it'll mean having to sort the crazy aerial angle, not having to plug the aerial hole and not having to drill out those fused Al/steel A-pillar screws...(which gives me nightmares)

The 'splitter's' already arrived, but I'm not holding my breath. If it doesn't work I'll look at finding a replacement aerial along the lines of yours then brave the sticky/A-pillar debacle if absolutely necessary. The physicist in me would like to know more specifics about Geoff's home-made-dipole-under-the-boot-lid - that really appeals to me...

[Blaster]

Yep that looks really neat; it's a vast improvement on all those aerials at crazy angles...but I bet that mast is unobtainable now?

Looks like your right. I had a quick look for one.

Another good reason for not throwing things away

[Saltire]

Yep that looks really neat; it's a vast improvement on all those aerials at crazy angles...but I bet that mast is unobtainable now?

Looks like your right. I had a quick look for one

I think it became this.

[chrism]

Yes all my i/net searches seem to be leading back to this one and it's very similar to Blaster's.

It looks like it'll be able to cope with the curvature of the body and point upwards, too. Expensive, but if it pulls in the signal and points upwards I reckon it might be worth it

I've got a feeling that it'll need to be earthed(/ground-planed?) somehow, but the Lotus has a separate earth strap in that area under the skin hasn't it? From the dim distant past I get the impression that this earth connection might be circular band held with a nut + bolt (like a battery connector) around the bottom of the aerial post - but it looks like this one hasn't got a long enough post below the skin(?) to connect it to.

(Hmm...I expect someone on the forum has already managed to solve this issue, perhaps?)

[chrism]

A couple of more thoughts...

Just spoken to an ex-Merchant Navy Radio Op, whose skills continue in the HAM radio field.

He absolutely supports GeoffSmith that DAB signals are vertically polarized, but interestingly thought that attaching the DAB sticky to the metallic w/screen 'might not be all that necessary' (- kind of, try it and see...)

[Roger D]

To add to the chat about fitting DAB Ariel’s I recently fitted a combined FM and DAB replacement Ariel using the original rear wing location.

The unit I used only cost £22 from eBay at the following link. https://www.ebay.co.uk/itm/Roof-Mount-A ... 635-2958-0. I have no connection with the seller or their products other than I bought mine from them.

I routed the new Ariel along the original route and took a power feed from the dash clock. I also added an additional earth for the Ariel mount connecting it to the boot hinge earth.

I all works just great and I get good reception for both FM and DAB.

The really neat thing is near identical appearance to. Original (it looks just like the one on the blue Elan several entries above no unsightly stick on bits on the windscreen.

For good measure I also did the same with my S2 Elise replacing the original unit with the same FM/DAB Ariel and that works great as well.

[chrism]

Now that's 'upped' the game and ticks nearly all the boxes (and I'm so pleased it looks the part - like Blaster's Bosch unit)

Finally, 1. does it point upwards ok and dispense with that crazy leaning? And is it easy to 'route'? (haven't got the elan yet...)
and 2. is the earthing straightforward? ie anything to be wary of?

If these last points are ok then it's 'job done' and I won't even bother with the splitter

Just what I wanted to know...Brill ...plus I won't have to lock horns with those dratted a pillar screws

[Blaster]

This is the ground plane in my boot, or what's left of it. Never looked up when fitting the aerial just did it by touch so that's the first time I looked at it.

It works, I will just add it to the list of things the I may get round to doing.

[chrism]

So, is this ground plane the 'earth', or did you run a separate lead like Roger D?

I reckon if you didn't there's not much electrical connection there (if any , sorry) to be an effective earth/reflector/ground plane and my HAM-radio pal might be vindicated...(and it doesn't really need it in a strong, well-supported signal area)

[Blaster]

It does actually make contact but if I had looked before I fitted it I would have done something better.

But it does work, I am in a poor coverage area and it sometimes gets a DAB signal even without the mast attached.

The thing is I am also a HAM.

[chrism]

Al foil or conductive paint, I wonder?

In any case I reckon a separate earth lead won't go amiss whilst under there...

[Blaster]

It is self adhesive aluminium foil. The teeth of the mount bite into it.

[dapinky]

When I replaced my FM aerial I 'repaired' the ground plane with some thick aluminium foil and spray adhesive..... very fiddly to do, but seems to work okay.