Two directions at once, or one big long-shot?

[billg]

Hello experts,

It has been a long time since I've tried to use the ol' rabbit ears, but I recently moved to an older home in Delray Beach, FL, (which is approximately 25 miles south of West Palm Beach and 45 miles north of Miami) and have decided to give cord-cutting a shot since Comcast wants me to shell out $$$ for all-new cabling before they'll let me have a box. The home was upgraded with a corrugated metal roof, which is great for hurricane protection, but terrible for indoor antenna reception. Thus begin my problems...

First, here's my map:

http://www.tvfool.com/?option=com_wr...d243a818aae652

and a similar thing from antennapoint, which really highlights the density of the two distributions:

http://antennapoint.com/antennas/sho...&commit=Search


I started out by testing an old (circa-2006) Radio Shack amplified indoor UHF/VHF antenna placed near the top of our peaked roof, about 12' above the ground. I borrowed this from my office in Fort Lauderdale, where we do a good deal of testing digital reception, so I know the antenna is in good working order. I was able to tune the FOX affiliate, both ION channels, WHDT, and a few others (my TV "found" 12 channels, but only 9 showed up in the list). I was not able to resolve any of the VHF signals at all, despite some serious acrobatics holding the antenna. At the suggestion of a friend, I next tried an amplified Mohu 50. This improved things a bit -- my TV now found 24 channels, and 16 showed up in the list. If I held really steady at one particularly awkward angle I could tune one VHF channel (the NBC affiliate), but in that contortion I didn't get any of the other stations -- I don't care what Mohu says, their antenna is definitely *not* omnidirectional, it's extremely picky about placement, at least in my house.

So, the Mohu went back and I am now looking at rooftop options. My problem is that being between two metro areas, there are two potential sources for me to focus on. All I really want are the four major stations (ABC, NBC, CBS and FOX), plus PBS. Based on the map, it initially seemed like my best bet was to get a directional antenna and point toward the northerly stations in West Palm Beach:

NBC @ 312 deg, 12.3 miles away
FOX @ 304 deg, 13.2 miles away
PBS @ 304 deg, 13.2 miles away
CBS @ 313 deg, 12.1 miles away

The trouble is that there are two ABC options, neither of which are great:

ABC (WPBF) @ 336 deg, 49.6 miles away
ABC (WPLG) @ 195 deg, 35.8 miles away

So it seems like I have a couple of potential options with regard to roof-mounted antennas:

- Get an amplified omnidirectional antenna like the Mohu MH-110585 Sky 60, LAVA OmniPro HD-8008 or Winegard MS-2002, and hope that it's good enough to grab one of those far-away ABC signals,

- Get a long-range unidirectional antenna like the RCA ANT751, Lava HD-2605 Ultra, Antennas Direct C2-V-CJM ClearStream 2-V or Channel Master CM-4228HD and point it somewhere between 304 and 336 degrees (probably aiming more toward the 336 since the signal comes from further away) and hope that I get can pull ABC while still getting the other stations, or

- Get two unidirectional antennas, point one between 304 and 313 degrees, and another at 195 degrees, and then set up some kind of bandpass filter or something so I can combine the two into one signal to go into my one TV tuner

- Ignore all of the closer, West Palm-based stations and just point a single long-range directional antenna toward the bulk of the Miami stations, between 191 and 196 degrees (all between 35-40 miles away)

One thing I really DO NOT want to do is rely on a motorized antenna. We are quite close to the water, and outside electrics don't hold up long in the salt air, no matter how rugged they claim to be. Plus, the thought of having to explain yet another remote to my wife and kids is... undesirable.

So my to the RF experts out there are:

1) Which of the options above (if any) are most likely to work? What would you recommend?

2) Do multidirectional antennas actually work?

3) Based on my map, there's no need for an antenna that gets the VHF low band, right? The lowest channel that I might possibly be interested in tuning is listed as 7

Thanks so much!

[StephanieS]

Greetings Billg,

A reception plot many would love to have!

If you just want the "big 5" - the solution is a Antennas Direct DB8e with one panel pointed to magnetic 315 and the other panel pointed to magnetic 200 will do just dandy on UHF. The DB8e is nifty because it gives a flexibility to adjust both panels to unique headings.

There are enough VHF signals in your reception area that even though likely not fully needed, I'd add a high-VHF antenna along the lines of a Antennacraft Y5713 orientated to magnetic 200.

I would expect you will have a full set of the "big 5" along with many duplicates from each market.

A Antenna's Direct EU385CF combiner would a good choice. This mounts on the mast and you hook the DB8e coax to the EU385CF UHF input and then the Y5713 coax goes to the EU385CF VHF input. Both antennas are combined to one coax heading into your home.

A preamp is likely not needed. You have a large amount of signal.

Cheers.

[ADTech]

Assuming you have no trees, buildings, or other obstacles in either signal path:

DB4e with reflectors removed (drill out rivets) plus a VHF1 Retrofit kit mast mounted above the reflector-less DB4e. The result will be a bi-directional UHF/high VHF system that should adequately cover both your markets.

No low-VHF is needed. The only one on your chart is on channel 6 out of Miami which operates as a pseudo FM station but it will be gone in less than a year when all analog must end in the US.

You will need to get the antenna well up above the metal roof so as to avoid reflected signals that must travel across the roof. I usually suggest a 10' mast on either a gable, wall, or tripod mount

[billg]

Thanks for the quick replies!

To my layman's eyes the DB8e basically looks like 2 DB4e's connected together -- is this a fair assessment?

If so, if I decided to go with the DB8e to be able to point in both directions at once, would it still be a good idea to remove the reflectors? And if that turned out to not work (or make things work), would reconnecting them with some small nuts and bolts restore their effectiveness (since I can't re-rivet anything)?

With regard to mast height and placement, I'm pretty sure a 10' mast on top of my roof is not going to fly -- all of the coding down here is geared toward reducing damage during catastrophic windstorms (e.g. hurricanes), and the code enforcement people are vigilant. However, I do have a large stretch of flat asphalt roof about 20 feet north of the metal peaked roof -- do you think I could get away with a shorter tripod on this section of roof? It's also in the back (north side) of the house, so it'd be less visible from the front (south side).

Finally, I see both of you recommended Antennas Direct antennas, but not the ClearStream ones that they so heavily advertise here and on the site. Any reason for that?

Thanks again!

- Bill

[timgr]

This may be of interest to the OP

http://www.fcc.gov/guides/over-air-r...n-devices-rule

"Masts higher than 12 feet above the roofline may be subject to local permitting requirements for safety purposes."

Seems like the suggested 10' mast is within the letter of the law. I'd follow ADTech's advice to get the antenna well above your steel roof to avoid reception problems. I'd also contact my local safety enforcement agency for a friendly conversation in light of the FCC regulations.

Yes, it looks to me like the DB8e is two DB4e panels connected together. Supposedly the two panels aimed in different directions perform differently than a single DB4e pointed in one of the two directions, ie not quite as sensitive as a single panel pointed at a specific station. The most sensitive configuration is both panels pointed in the same direction.

Not an industry member, but I would guess that removing the reflectors from a DB8e would make it bidirectional the same way removing the reflector from a DB4e would, as long as both panels are pointed in the same direction. I would also guess that if you remove the reflectors and point the two panels in different directions, you could have trouble because you may create a signal multipath problem (phase incoherence between the two panels for a single station).

[ADTech]

This is one of those times where "less is more". The reflector-less DB4e + VHF dipole is suggested for this application

[billg]

Thanks again.

I'm putting together a list comprising the DB4e, all the necessary mounting goodies, cable, etc. Assuming my cable run is unsplit and less than 100' total, I shouldn't need a preamp, correct?

Based on my maps, do you have any guidelines for orientation? I'm assuming that no matter where I start I'm going to be spending some quality time up on my roof while asking my wife to rescan the channels, but, any recommendations would be welcome


- Bill

[ADTech]

I don't see any need for any amps.

Orient the antenna elements so they point east-west. Reception is from directions perpendicular to the elements. Adjust as needed.

[billg]

Originally Posted by ADTech

Assuming you have no trees, buildings, or other obstacles in either signal path:

DB4e with reflectors removed (drill out rivets) plus a VHF1 Retrofit kit mast mounted above the reflector-less DB4e. The result will be a bi-directional UHF/high VHF system that should adequately cover both your markets.

Hi ADTech,

I just received my DB4e and am curious about your statement to remove the reflectors. In the box I see two large pieces: one with the bowties, and one with two square metal grids. The instructions refer to the grids as the reflector, and instruct me to attach the bowties to the reflector using some 5" bolts with aluminum standoffs.

Is your suggestion to simply not use the reflector piece at all, and only mount the bowties? If so, there's nothing to un-rivet, right? I'd simply not connect the bowties to the other piece?

Thanks!

[timgr]

I'm not ADTech but I own a DB8e which has similar construction. I recall you need the upright that the reflectors are mounted on to enable mast mounting. I'd assume it also make a difference in the strength of the support for the bowties.

[ADTech]

You have to drill out the rivets that hold the grids to the reflector support spine. There's no other way. If re-assembly is later required, use standard #10 hardware.