Central/Eastern USA, Gulf Coast, Mexico, Caribbean

[300ohm]

Agreed, during storms our reception of DC becomes very unreliable.

What present antenna do you have ?

Is it possible to get the antenna higher, so its near the thinner part of the trees ?

Besides the trees, there are hills between you and Balt and DC. Try tilting the antenna upwards a bit, say 10 or 15 degrees. You should be able to do that with most antennas by adjusting the ubolt and bracket.

My experience with corner reflector yagi (and yagi and lpda) type antennas is that they perform worse for the same gain in a tree blocked environment than broadside type antennas like the GHs and the bowties and hoops.

[otadtvman]

We're currently using a broadside type antenna, a CM-3021 4-Bay Bowtie with our old CM-0100DSB pre-amp inside a South-facing, 2nd-floor, bedroom window w/o a screen. This works well for all of DC (in good weather only) and gives us variable reception from Balt. It also performs much better than our old 2nd-story attic antenna.

The Norway Spruce can grow 2-3+ feet per year their first 25 years ... will easily grow to over 100 feet tall ...

These Spruce are now 25-30 yrs old. See link for picture in post #3. A tower is not in the budget. Max height = 2-story house + mast.

OK, I'll tilt the antenna upwards 10 or 15 degrees.

We have a rotator. Balt. (42 mi.), Harrisburg (65-68 mi.), Lancaster (59 mi.), & York (59 mi.) are the alternatives if DC becomes problematic due to the trees.

[Cham]

That sigma antenna looks just too fancy to work well... but it likely works fine.
I would also expect similar results from a GH antenna, but if you want to impress your neighbors the sigma is the way to go.

In theory the full wave loop element should have more gain than the same 1/2 wave element design, but I have not seen a major advantage using director elements in a full wave loop configuration in the low frequency bands. They are more popular in the 1.2-1.8 and 2.4GHz bands due to broadband nature, which is also advantageous for the TV UHF band. The sigma may have more than one loop in the driven element "assembly" to make it more broad band, and the grid reflector also rather non frequency critical.

Let us know how it works if you order one!
-C.

[300ohm]

OK, I'll tilt the antenna upwards 10 or 15 degrees.

I believe youll need a longer bottom ubolt, which is available at Home Depot. I would loosen the top ubolt, then install the longer bottom ubolt with a plastic or durable wood spacer in between the mast and the bracket. That will give you a tilt.

Attaching a wider reflector of say 36" wide by 30" high of 2" X 4" mesh (2" side going up and down, 4" side left and right) to your CM-3021 would dramatically increase your vhf-hi gain and help a bit on uhf gain as well.

See link for picture in post #3.

Well, at least you have about 75 to 100 ft of clear area before the trees. I hope your neighbor realizes its not cheap or easy removing those trees when they get old, heh.

[otadtvman]

Hello Cham,

Originally Posted by Cham

I would also expect similar results from a GH antenna, but if you want to impress your neighbors the sigma is the way to go.

We're not looking to impress our neighbors. Every house in our neighborhood lacks a roof-top antenna as they are all connected to Comcast or satellite TV.

The Sigma 6HD (3' L) or 9HD (4.25' L) are appealing due to their respectable gain and shorter length compared to a 91XG (7.75' L), which makes them less conspicuous & less prone to wind &/or ice damage.

Originally Posted by Cham

They are more popular in the 1.2-1.8 and 2.4GHz bands due to broadband nature, which is also advantageous for the TV UHF band. The sigma may have more than one loop in the driven element "assembly" to make it more broad band, and the grid reflector also rather non frequency critical.

Per Sigma 6HD (6 elements) brochure:

The original design of the new aerials patented by Fracarro, allows a particular directivity (with the maximum reduction in interference) and a maximum gain (17dBi*) and is also high throughout the whole reception band.

The gain achieved is comparable with an aerial twice its length!

*Sigma 9 HD (9 elements) - 18.5dBi

However, the brochure and data sheets don't specify the number of loops in the driven element "assembly"

Can you suggest a basic primer on full wave loop elements? Thanks.

[otadtvman]

300ohm,

Thank you very much for the CM-3021 modification instructions to

Originally Posted by 300ohm

dramatically increase your vhf-hi gain and help a bit on uhf gain as well.

• longer bottom ubolt
• plastic or durable wood spacer
• 36" wide by 30" high of 2" X 4" mesh

Sounds straight forward and simple. However, 4.1 (UHF 48) is the least reliable during a storm.

Norway Spruce last more than 100 years, so our neighbor probably won't have to worry about removal costs.
Norway Spruce windbreak: Our neighbors could not have chosen a more perfect DTV OTA "counter-technology."

[300ohm]

36" wide by 30" high of 2" X 4" mesh

If the CM-3021 is the same as the CM-4221a (which I read it was) make that 36" by 36". That will help UHF even more. (the existing reflector should be 36 inches high) Just attach the 2" X 4" mesh to the existing reflector, so the reflector center will remain 1" X 2" mesh.

[otadtvman]

OK: 36" wide by 36" high of 2" X 4" mesh

Better UHF performance is what's needed most.

Is there more than one quality of 2" X 4" mesh (galvinized?) - that will stand up to the elements longer?

Thank you!

[300ohm]

However, 4.1 (UHF 48) is the least reliable during a storm.

With the wider reflector mod, you should be able to pick up NBC from Baltimore rf 11, and from Lancaster rf 8. One of those should be clear during a storm, heh.

[otadtvman]

Originally Posted by 300ohm

(the existing reflector should be 36 inches high) Just attach the 2" X 4" mesh to the existing reflector, so the reflector center will remain 1" X 2" mesh.

The original reflector is 36" high x 20" wide.

1.) Is there more than one quality of 2" X 4" mesh (galvinized?) - that will stand up to the elements longer?

2.) Is there a recommended attachment method for the 36" x 36" mesh to the existing reflector? Zip ties?

Originally Posted by 300ohm

With the wider reflector mod, you should be able to pick up NBC from Baltimore rf 11, and from Lancaster rf 8. One of those should be clear during a storm, heh.

Sounds good.

Thanks!

[300ohm]

1.) Is there more than one quality of 2" X 4" mesh (galvinized?) - that will stand up to the elements longer?

Yes, there are many different gauges and quality of galvanization or plastic coatings. For reflector gain purposes in this case, the differences between them are going to be very tiny, so even plastic coated is fine.

Is there a recommended attachment method for the 36" x 36" mesh to the existing reflector? Zip ties?

Yes, UV resistant zip ties will work, but its hard to determine their future quality too. To be safe, I would just twist some soft copper or aluminum wire to tie it on to the existing reflector and then clip off the excess ends of the wire to make it neat.

[otadtvman]

Thanks, will do. Will this mod be sufficient to consistently receive all VHF-hi within 45-miles (DC & Balt) or will we need a BLV6F, ANT3100510, YA-1713 or Y10-7-13?

When I tested the CM-3021 on top of the roof, the VHF performance was non-existent for VHF 7, 8, 9, 11, 13.

However, as an indoor 2nd-floor window antenna, we consistently receive 7 & 9, 11 much of the time, and 13 some of the time.

[edtrutone]

mechanical wise the 91xg is like a kia vs Ferrari but w/lifetime warranty. so you cant go wrong. the sigma9 hd has 1 db advantage past 700 MHz so it is useless
as per fracarro charts. i am currently using the blu 420f here in Mississauga. the
sigma series of antennas have a massive reflector of all my collection of yagis.

[edtrutone]

the big plastic driven element of the sigma6 hd are the same as the blu series of antennas.

[otadtvman]

Originally Posted by edtrutone

mechanical wise the 91xg is like a kia vs Ferrari but w/lifetime warranty. so you cant go wrong. the sigma9 hd has 1 db advantage past 700 MHz so it is useless as per fracarro charts. i am currently using the blu 420f here in Mississauga. the sigma series of antennas have a massive reflector of all my collection of yagis.

Gain at ch-14:

I've read many excellent reports on the 91XG. It's the most cost-effective of these choices. 11.8 dBi (~9.65 dBd) @ 470 Hz

The Fracarro sigma 6 & 9HD look appealing due to their respectable gain and smaller size - Less prone to ice &/or wind damage and less conspicuous from the street.
Sigma 9HD provides 14 dBi (~11.85 dBd) @ 480 Hz
Sigma 6HD provides 13 dBi (~10.85 dBd) @ 480 Hz

Which UHF yagi is best able to resolve or minimize multi-path interference? That's our biggest challenge. Thanks