Technical rationale for a horizontal polarized FM dipole to transmit (92.6 Kilkenny)?

Antenna

Technical rationale for using a horizontal polarised dipole aerial to transmit on FM? (92.6 Kilkenny) ?



Here is a picture I took some months ago when I was in the area - of the transmit aerial of 'Dreamtime Radio 92.6FM', an 'institutional' station off the Callan Road on the outskirts of Kilkenny city, run by 'SOS Kilkenny' at a campus for people with intellectual disability.

What is the technical rationale for using a horizontal polarised dipole to transmit on FM?
Doing this with one dipole results in significant RF power 'wasted' straight up into the sky and also down to the ground immediately below the aerial, - RF power which would be providing more coverage across land with the same of lesser transmitter power if the same dipole was vertical?
As it is coverage would be OK broadside to the horizontal dipole, but reducing to serious nulls off the ends of it ( a figure-of-8 sort of pattern).

I presume it is deliberately done to limit coverage? , especially to car radios which generally poorly pickup horizontal-only polarised signals (compared to vertical or mixed) .
Driving just a short distance away on the public road outside, some distant RnaG transmitter(s) started to make their presence felt! (the low modulation of dreamtime not helping either)

'Dreamtime' is easily the smallest FM radio station licenced in Ireland. Similarly licenced hospital stations in Ireland do not have such severely constrained coverage as this.
The station didn't have RDS when I heard it.

Dreamtime 92.6 is on for limited hours (30 hours over weekdays?) every week and shuts down completely outside of hours (no automated music service the rest of the time unlike similarly licenced hospital radio stations)

They were on a different FM frequency (90.9) when they first came on some years ago but later were moved to 92.6MHz

Came across a video which shows what their studio looks like:
https://youtu.be/ID223Bxy038?t=35

Losty Dublin

In certain circumstance of a low tx site such a set up can allow signal to lift up and then outwards. Kilkenny, being a town of narrow stone buildings and several slight hills, may be one such circumstance where it's slightly better to do this than relying on a regular aerial.

JDxtra

Done in error as opposed to some intentional reason I would say. If they have low modulation and no RDS as well, they may not have access to professional help.

The BAI will restrict the broadcast hours and ERP of the station. There is no advantage to them of further limiting their range by mounting the antenna the incorrect way.

godfrey

Nothing about that installation looks like it was done by an RF engineer. Polarity and proximity to the building and the ground are definitely not what's on their licence spec.

They're probably enjoying low heating bills by roasting the output stage of the transmitter though! Someone put an SWR meter on that yoke...

In my opinion.

g

Losty Dublin

JDxtra wrote: »

Done in error as opposed to some intentional reason I would say. If they have low modulation and no RDS as well, they may not have access to professional help..

Even low power BAI stations are required to have competent professional transmission engineers. If an error then this would should have been spotted at some stage over the years, or indeed a tx blow out.

Tax The Farmers

Horizontal polorisation has never been the norm/standard for FM broadcasting in Ireland. Historically it was the case in other countries but most of these places shifted to mixed, slant or circular polorisation when portable/car receivers became ubiquitous.