Pointing A Directional Antenna EXACTLY At A Tower

[prcguy]

I think both techniques are required.

1) If you swing a yagi looking for a peak you are likely to get a reflection from a water tower or building.
2) Calculating the expected direction informs you that you are "on the mark" as far as the peak you find. If you have a scanne like the BCD536HP, the bar graph is rather tiny and not intuitive.

If anyone knows different way to skew the 6 dB points accurately with that scanner I would love to know. I guess I could insert a 3, 6 and 9 dB pad and figure out the actual bar that responds.

There will be cases, for those inside the simulcast footprint where the F/B or a side null will be be useful to help reject an interfering site. In that case the nose of the yagi might be off center with the direction. In other words trading 3 dB signal for 10 dB interference rejection.

You can detune 2dB, 3dB, 6dB, even 10dB as long as you can measure the exact level either side of peak then split the difference. I believe I found about 4dB was good for the DirecTV Slimline dish and that’s what the published procedure dials up. Big satellite dishes can degrade to less than 1dB during an auto peak as you don’t want to affect service by moving the antenna too far.

 

[Ubbe]

Probably better to use an accurate S meter then detune off one side until it’s degraded about 6dB or 1 S unit, note that direction, then go through the peak to the other side until it’s degraded the exact same amount then park it in the middle of those two readings.

Isn't that how we in all times have tuned everything from filters to yagis to sat dishes and carburettors in engines and practically anything that needs tuning? Detune to one side and then detune to the same amount of loss to the other side and choose their middle point. Otherwise it can be difficult to know if you are tuning something correctly and you will also get a feel for if anything are unsymmetrical, the loss comes quicker at one end, that then might need to be investigated.

For simulcast antenna direction using a non-simulcast scanner you could end up with a better result not to aim at the strongest site that have other sites too close in angle to it, but instead aim at a weaker site that are more alone in that direction that will give a greater signal level difference to other sites. If you manage to attenuate the signal down to -100dBm then the signal from other sites could be down in the noise floor and have no impact on the signal quality. Enabling the scanners attenuator for that system will usually help to come down to those signal levels.

/Ubbe

 

[dlwtrunked]

I think both techniques are required.

1) If you swing a yagi looking for a peak you are likely to get a reflection from a water tower or building.
2) Calculating the expected direction informs you that you are "on the mark" as far as the peak you find. If you have a scanne like the BCD536HP, the bar graph is rather tiny and not intuitive.

If anyone knows different way to skew the 6 dB points accurately with that scanner I would love to know. I guess I could insert a 3, 6 and 9 dB pad and figure out the actual bar that responds.

There will be cases, for those inside the simulcast footprint where the F/B or a side null will be be useful to help reject an interfering site. In that case the nose of the yagi might be off center with the direction. In other words trading 3 dB signal for 10 dB interference rejection.

I have found the best thing to do in this regard is to use an SDR (AGC off or tune the SDR to a nearby unused frequency) and watch the SDR spectrum display paying attention to the frequency of interest and I use an Arrpw Antenna DF loop. Works very well and in fact, with a directional antenna, I use this for DF/fox hunting with excellent results. I once did this my way with another person using a beam antenna on a non-SDR to locate an interfering signal on a repeater . The results were good for both but I got my bearings in far less time and effort with better accuracy.

 

[slicerwizard]

+1 for use a cheap SDR dongle.