Advice on Choosing an Indoor Antenna

[teegee]

My TV Fool report: http://www.tvfool.com/?option=com_wr...f1f0c0c5ae66a8

Recent cord-cutter unable to get the following stations that are important to me Ch 4-1 (WRC - NBC), Ch 7 (WJLA - ABC), & Ch 9 (WUSA - CBS). Sometimes I also lose Ch 5 (WTTG - Fox) & Ch 50 (WDCW - CW). Having a hard time without these - especially the 1st 3. Would like to get these stations consistently along with channels 22, 26, & 32 (all local PBS stations). Also enjoyed Ch 50-2 (local Antenna TV affiliate) which disappeared weeks ago after a storm - but I can live w/o it.

I have a non-powered Mohu Leaf installed (original model, I think). Apartment resident - so roof antenna not an option. Any recommendations on the best antenna to buy?

[rabbit73]

Welcome to the forum, teegee:

Oh, Wow! This looks like a serious multipath reflection problem, with signals bouncing around in all directions.

Your signals are very strong, but you will need to do a lot of experimenting with indoor antennas and their location. If you extend your coax with an F81 coupler you can add more coax to allow more choices of location.

If your apartment has a window that faces SW without lowE glass or a metal screen you might be able to put your antenna inside that window with promising results. If not, you have a lot of trial-and-error ahead.

Maybe you are lucky enough to have a balcony.

Your antenna doesn't have an amplifier, which is good because it probably would be overloaded. Your antenna works better for UHF than VHF-high, real channels 7-13 (not virtual channels).

You might have better luck using a small outdoor antenna inside because it will be more directional to reject some of the reflected signals in that congested area.

[teegee]

Very helpful rabbit73. I appreciate it. Could you recommend a particular outdoor antenna for that purpose?

[rabbit73]

Could you recommend a particular outdoor antenna for that purpose?

That's a tough question for a difficult location, but I'll give it a try.

Most of the indoor antennas are the flat type, which you have already tried.

The reviews of indoor antennas are mixed and varied going from Great to Awful because indoor reception is much more difficult than with an outdoor antenna. When the FCC made their original tests of digital reception, they assumed that everyone would have at least an outdoor antenna at 30 ft. and set the transmitter power levels allowed based on that assumption.

They soon found out that those power levels were not adequate, and have needed to authorize higher power levels for the same coverage areas as analog signals.

However, in your case, the signals outside at your location are so strong that the signal power for your strongest signal is highlighted in red (-11.2 dBm) to indicate possible overload.

So, the problem in your case is two-fold. The strength of your signals inside your apartment is unknown, because the attenuation of the building construction is unknown.

The second problem is multiple reflections of signals that interfere with the direct signals from the transmitters. This is called multipath. The reflected signals arrive at your antenna at a different time than the original signal, which interferes with the original signal and causes errors in the digital stream. The tuner is able to correct errors up to a certain point using the FEC (Forward Error Correction). When that limit is exceeded, the signal suddenly develops pixilation and freezing at the "Digital Cliff" and finally drops out.

In the days of analog television we also had multipath reflections which created a secondary image that we called "ghosts."

Since you have already tried a flat antenna, the only improvements I can think of are to try different antenna locations, try adding an attenuator after the antenna because your indoor signals might be so strong that they create tuner overload, and add a reflector to an indoor antenna to make the antenna more directional to eliminate some of the multipath reflections.
Variable Attenuator
https://www.antennasdirect.com/store...ttenuator.html

The antennas with reflectors that you might consider are made by Antennas Direct. They are more expensive than many indoor antennas, so you will need to decide how much you want to spend on antenna experiments. I can't guarantee that my ideas will work, and would like forum member ADTech to double-check my analysis, because his advice is excellent.

The antennas that I would consider have reflectors, and are primarily for UHF, so you would need an added VHF antenna for real channels 7 and 9.

Indoor Antennas
https://www.antennasdirect.com/store...-antennas.html

All Antennas
https://www.antennasdirect.com/store...-antennas.html

My choices:

ClearStream Micron R Indoor Antenna, Black or Colors
Does have a reflector, but isn't for VHF. You would need to add a separate antenna for VHF with a UVSJ UHF/VHF combiner.

ClearStream™ 1 Convertible Medium Range Indoor/Outdoor DTV Antenna
https://www.antennasdirect.com/store...V-antenna.html

You would need to add the VHF Retrofit Kit for VHF Antenna Reception
https://www.antennasdirect.com/store...rofit-Kit.html

Possible upgrade: ClearStream™ 2V Long Range UHF/VHF Antenna Complete Combo Pack
https://www.antennasdirect.com/store...-Complete.html

DB2e Extended Range Outdoor TV Antenna
https://www.antennasdirect.com/store...r-Antenna.html
You would need to add the VHF Retrofit Kit for VHF Antenna Reception
https://www.antennasdirect.com/store...rofit-Kit.html

If 7 and 9 aren't good enough with the VHF Retrofit Kit, you could add a separate VHF antenna with a reflector like the ClearStream™ 5 VHF Ultra Long Range Outdoor TV Antenna
https://www.antennasdirect.com/store...V-antenna.html

Some cases of multipath reflections are so severe that it has been necessary to enclose the antenna in a metal enclosure, with an open end in front of the antenna, to limit the antenna beamwidth to a very narrow angle.
Chattanooga TN: Got Atlanta But Few Locals
The thread:
http://www.avsforum.com/forum/25-hdt...-locals-2.html
Photos at post 60:
http://www.avsforum.com/forum/25-hdt...l#post21358820

Bill Naivar of Georgia Tech also built an anti-ghosting antenna in a trash can. I see that the link is still listed on Google, but Norton Internet Security has warned me off and blocked me.

[ADTech]

I usually just go straight to the C2V, it's my favorite for use indoor. If you pick the newest version up from Walmart or Best Buy, it should be capable of free standing placement. You could also try the C1 convertible, a close second choice, but you'd have to order the VHF kit separately off our web site.

FYI, the newest versions of both the Micron reflector and the newest version of the VHF-1 module are now made so they will mate together. This has been a rolling change, so there's really no good way to determine what you have until you examine the units.

Because you're a thousand plus feet below the transmitting antennas, your signals will be markedly lower than the levels indicated in your plot. Overload won't be an issue unless an amplifier gets into the system.

[rabbit73]

ADTech:

Thanks for double-checking my analysis, and adding the update on modifications being made.

[rabbit73]

The links to Bill Naivar's Anti-Ghosting Antenna to minimize multipath reflections were blocked by my Norton Internet Security, but I was able to find enough images at Google to describe his experiments, while giving him credit for his images.

Bill's first anti-ghosting antenna was a Winegard PR-9014 UHF antenna in a screened enclosure. See Attachments 1-3.

He used a spectrum analyzer to view the shape of the digital signal to look for signs of multipath. This is not always a fool-proof method to detect multipath as Trip in VA found out. It is possible to have a good looking trace, even when there is a serious multipath problem. This is because the reflections can fill in the dips in the trace. The analyzer records amplitude during the trace, but doesn't account for time differences between the original signal and the reflections according to Dr. O. Bendov in his paper DTV Coverage and Service Prediction, Measurement and Performance Indices.

See Attachment 4 for the bad looking ragged spectrum analyzer trace by Bill, BEFORE using the anti-ghosting antenna. Attachment 5 is the good looking spectrum analyzer trace, using the Winegard PR-9014 anti-ghosting antenna.

Chattanooga: Trouble getting OTA Signal

http://www.avsforum.com/forum/25-hdt...l#post22156611 post 25
http://www.avsforum.com/forum/25-hdt...l#post22172949 post 26

Bill's second antenna was a double bowtie in a trash can which gave better results. Attachments 6-8.

Can you see the anti-ghosting antennas built by Bill Naivar of Georgia Tech in this photo?

I took a standard UHF bowtie antenna and mounted it to the bottom of the can. The metal bottom makes a great back reflector, the can provides the multipath shielding, and the U-bolt that came with the antenna mounts the whole thing on the pole. (I can even use the handles to tie guy wires to so that the wind doesn't move the can.) I mounted a F-81 barrel for the coax connection. And I even got 2 dBmV MORE signal level than my original design!

http://mackys.livejournal.com/713021.html

Attachment 9 is the spectrum analyzer trace for the double bowtie in the trash can.

[Jake V]

LOL - What would the HOA say if you needed to mount your television antenna in a trash can on the roof of your townhouse? What fun!

[rabbit73]

Analog multipath in the UK causing ghosts.
http://www.frisnit.com/radar/

Can you see the ghost image?

[rabbit73]

teegee:

You probably wouldn't want to put your antenna in a trash can, but it made TV reception possible with an indoor antenna for Trip in VA when he was in Chattanooga.

Please let us know how your antenna experiments work out. It might help other people faced with indoor antenna reception problems.

Best regards,
rabbit