LPFM_Radio : Message: Re: [LPFM] RSM Comment on Power etc.

It's absolutely rediculous to think that 1 watt or even 10 watts on 107.7 is going to affect professional equipment over 1MHz away. It must be some sort of political thing.

There was some argument by RSM that there are some aging equipment being used in aviation, but even so, even ancient valve technology of the 1960's are much more narrowly filtered than that.

Regarding circular radiation antennas, I want some! I've discussed this at length with a someone who makes his own FM antennas.

You see, the regulations allow 500mw in both planes, that is horrizontal and vertical plane. Only transmitting in the vertical plane means radios need a vertical antenna to receive the signal best.

A circular antenna radiates in all planes vertical, horizontal and everything in between. Because of this, the gain the the antenna is -3db less than a single plane antenna because the power is spread in other planes, but in reality you get as many listeners as you did before, due to people using slant antennas, or bits of wire lying on the floor, etc. They will receive your signal much better.

But, according to a radiation meter, you are now only transmitting 250mw eirp, so you can now double the transmitter power and transmit 1 watt in 2 planes legally. It will definately increase coverage, and you'll also find much less fluttering while driving.

It's well known that horizontal radiation travels much further than vertical due to the magnetic waves of the Earth, and they also pass through trees much better.

However, I believe circular antennas by design have some gain in one direction, so unfortunately you need 4 antennas at 90 degrees to each other to get a full 360 radiation pattern.

They are not cheap, however, as they need precise measurements to get the radiation rotating properly. A slight mis-measurement can cause phase problems. But I hope to have 4 of these one day.

Ross.

----- Original Message -----

From: Gavin Stephens

To: LPFM_Radio@...

Sent: Thursday, March 08, 2007 8:00 PM

Subject: [SPAM-LOW] Re: [LPFM] RSM Comment on Power etc.

I was actually hoping perhaps that 5W was still on the table for lower frequencies but from that shared info Allen, well, at least we have gurl's for guard bands in NZ.

1 Watt is still better than 500mW. I haven't taken notice of how far a watt in mono would go.

I can understand the importance of the higher frequencies power pushing over a Watt. ILS systems start from 109MHz up. Although I think the lowest I've punched in a simulator in NZ was around 109.5MHz in Dunedin.

Speaking of using a watt and getting off topic a little, has anyone else done some experimenting with a circular antenna with 500mW yet? If so what there results where with such a low power. Also anyone used 45 degree mounted dipoles to provide more clock radio reception?

Gavin.

----- Original Message -----

From: Allen

To: LPFM_Radio@yahoogroups.com.au

Sent: Thursday, March 08, 2007 5:50 PM

Subject: [LPFM] RSM Comment on Power etc.

Hi all,
I share the following message which is just in from my contact at RSM
Cheers
Allen

----- Original Message -----
From: Jeff Hicks
To: Allen Little
Sent: Thursday, March 08, 2007 5:34 PM
Subject: LPFM Power Increase to 1 Watt eirp.

Hi Allen

As discussed on the phone this morning Radio Spectrum Management has
not been able to gazette the increase in power of the LPFM GURL to 1
Watt eirp because it has been necessary to perform further
engineering work on the effect that LPFM transmissions at the higher
power of 1 Watt eirp would have on the aeronautical Instrument
Landing Systems (ILS) which are used at major airports
around New Zealand to assist aircraft to land in inclement weather.

This work is being progressed urgently and we will have a result
shortly.

As also discussed please advise any LPFM groups that you are talking
to that while a power of 5 Watts eirp for LPFM was discussed in the
early discussion paper that the Ministry distributed and while this
paper is still on our website, there is no possibility that the
LPFM will be increased to the 5 Watt eirp power level. The
instruction from our Minister was to consider increasing the LPFM
power to 1 Watt eirp and that is what we are currently
working on as outlined above.

Regards

Jeff Hicks
Acting Manager, Licensing
Radio Spectrum Management
Ministry of Economic Development
PO Box 2847, Wellington 6015, New Zealand
Phone: +64 0508 776 463
DDI: +64 4 470 2307
Fax: +64 4 499 0797
jeff.hicks@med.govt.nz
http://www.rsm.govt.nz
Connecting you to fast, easy and effective radio spectrum services
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