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Discussion Starter #1
I'm new to antennas. I've done quite a bit of reading on this forum and elsewhere, and I was wondering if someone could help me out with my choices.

I need to build an indoor antenna for an apartment in the NYC area. The bulk of the broadcast towers are southwest of me, but my windows face east. So either the waves are going to make it through the building, or I've got to hope to catch what bounces from the other side of me.

Originally, I was looking at this design:

http://cachefly.oreilly.com/make/television/04/DTV_Antenna_FINAL.pdf



Then I found this site, and mclap's 4 bay design, along with the Grey Hoverman designs which, I assume, are improvements over the link I gave above?

Because I'm building an indoor antenna, I would like to avoid building a reflector if I can avoid it. If it's necessary, or would make a huge difference, than I'll do it. But if it's marginal, than I'd rather leave it out.

That being the case, which of the available designs would give me the best performance under my conditions?


 

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I've learned that the trick to receiving OTA in an apartment when the signals are local, strong and on the opposite side of your apartment window is to eliminate multipath interference.

When the tv signals have to travel through the building to get to your antenna they become weaker and have to compete with tv signals that bounce off another building and come from another direction. With analog this causes ghosting, with digital tv signals this causes drop outs and pixelation.

Here my local station 8.2 miles away with NM reading of 62.8 and on the opposite side of my unit. I can receive this station with just about any antenna. Here is a pic with the channel on my portable tv in the middle of my apartment - notice the antenna is not even extended:



However as I move around the apartment I'll get multipath or ghosting, in your case you'll get drop outs with digital tv because it starts to pick up the tv signals bouncing off different directions.

My advice is get a good directional antenna like a silver sensor. You can build the biquad or the double biquad for more directionality - they are easy to build. You don't need much gain in the antenna. Finding the sweet spot to pick up the signals without too much interference from the bounces is the trick. You might get it with the antenna close to the window or further away. Perhaps best reception will be pointing towards the tv stations or pointing towards a building near you.

A reflector will help because it will pick up only stations in one direction and not both. The silver sensor picks up in only one direction. The biquad without a reflector will pick up in both.

Hope this helps.
 

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Discussion Starter #4
Unfortunately, I'm on the first floor. So, I might need an antenna with greater gain - it's going to be a lot tougher for me than if I had a nice high vantage point.

Also, mounting externally is not an option, it really is going to have to be an indoor antenna.


So, given what hkaye mentioned, I guess I'm going to have to build a reflector after all.


All of that being the case, would the biquad still be my best choice? Or would the Hoverman the PDF I referred to, or the GH, or one of mclapp's 4 bay designs be better?
 

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A GH may be a little too big for indoor apartment use. Did you check out the Stealth Hawk designs?
http://www.digitalhome.ca/forum/showthread.php?t=123803
They are smaller and may be more suitable for indoor reception. There are some flat antennas on the market, but I would suggest building a simple Stealth Hawk and hang it somewhere with your apatment to see what reception is possible and then decide if bigger is worth the bother.
 

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Being on the first floor is unfortunate because tvfool doesn't seem to take into account local obstructions such as other buildings when displaying the signal strength. So tvfool can't give you an accurate signal strength indication.

I can receive my local channel 13 in my underground parking garage with the telescopic antenna extended on my portable tv. However we are not as densely populated here in Kitchener as you are in NYC - so your mileage may vary so to speak.

I would build the biquad anyways to try out. It's the easiest antenna you can build and does have a directional pattern. Even if it doesn't get you any channels it will give you an idea of how well you can receive channels. For example, the stealth hawk is more omni directional with less gain so if you can't receive anything with the biquad you won't get anything with the stealth hawk either.

If you have a lot of buildings around you and can't get anything at all you just might be in a dead zone and even the best antenna it will be a challenge.

If you can receive some of the strongest channels but want to receive more than it would be worth while building an antenna with a lot more gain like a SBGH which is better but of course a little bit more complex to build than a biquad.

My gut feeling says the bigger problem will still be multipath despite being on the first floor because even if the signal is weak - it will be weak from a number of directions.

Hope this is helpful.
 

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The OP indicates that antenna is limited to indoor use only. So, there is actually nothing to point at! Whatever signal is in the room is the only signal the antenna can receive. The Stealth Hawk is low gain and widely bidirectional, so it would best suite to pick whatever signals do infiltrate within the apartment. Hi gain antenna will achieve nothing more than a lower gain antenna if the reception is limited to what is infiltrating within the apartment. Actually, higher gain antenna indoors may actually become a multipath nightmare due to reflections rather than adding any advantage.

BTW: My realtime performance experienced with the Stealth Hawk far exceeds the bi-quad despite the NEC's modeling gain results.
 

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The OP indicates that antenna is limited to indoor use only. So, there is actually nothing to point at! Whatever signal is in the room is the only signal the antenna can receive.
Radio waves travel in straight line. There will be direction the antenna must point to pick up the strongest signal while ignoring reflections from other directions to eliminate multipath that will cause problems.

My sister lives in a condo not facing the CN Tower. I was able to get good reception from the tower by pointing the antenna at the building beside her and picking up the reflection which was stronger than the signals going through the building. Every case will be different so it's just a matter of being aware that reflections coming from different directions are there and a good directional antenna will work at picking up signals from that direction and ignoring others.


BTW: My realtime performance experienced with the Stealth Hawk far exceeds the bi-quad despite the NEC's modeling gain results.
That's great. But the Stealth Hawk still is not a directional antenna as you've stated many times that you can pick up Buffalo no matter direction you point the antenna at. So it's not going to work very well at eliminating multipath.
 

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Discussion Starter #9
I don't find the Hoverman from the PDF or mclapp's 4 bay to be complex to build - at least if I'm not building a reflector. And I know that even people higher up in my building used to have a nightmare getting signals (back when it was analog), so I think it's not unreasonable to bet that signal strength is going to be a challenge for me.

So I'm thinking that it might make more sense to build an antenna with better gain once (with the possibility of adding a reflector) than to have to build multiple antennas. How is the directionality of the Hoverman from the PDF or mclapp's 4 bay, *without* the reflector? Good enough that it might work, or is it a given that I'd have to use a reflector? And how do they compare? As much as I've read from the forum, I never found a clear and direct comparison of the two styles (at least without the reflectors).
 

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I believe since you are indoors you can use a simple reflector such as tin foil or metal screening because you don't have to worry about wind load. But I'll defer to someone like 300ohm who has a lot more knowledge on the subject.
 

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Discussion Starter #11
Ah! So is that what makes it more complex for the average builder? The need to account for wind load?

I was looking at people talking about just using a piece of cardboard covered in aluminum foil and comparing it with the far more complex discussions I was seeing on this forum about grid and mesh specs, and having trouble reconciling the two. :)
 

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The more complex reflectors will have better gain. There's a lot of tweaking discussions of getting better gain on channels - lots of discussion lately of getting reception on the VHF high channels.

So there will be less performance with a simple reflector. How much less - I'm not sure. But a simple reflector + SBGH will have a lot more gain than the biquad for sure and be more directional.

I built this SBGH using a Uhual box for moving pictures/mirrors -



On one side is the antenna and on the other side I used tin foil for a reflector. This antenna worked very well. However I opted for the biquad because with the biquad it was less directional and I was able to pick up the Buffalo and Toronto stations without needing to adjust the antenna. This SBGH antenna has better gain but also is more directional.

btw- better construction techniques than my quick cardboard box model will yield better results.
 

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Nice!

Well, then I'm back to my initial question... for a higher gain antenna in the unfortunate circumstances I'm in, would I be better off with a SBGH, a mclapp 4 bay, or the Hoverman design from the PDF?
 

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The PDF in your link is not a hoverman antenna - it's your typical coat hanger design. I built one of these as my first antenna - worked pretty good - I received quite a few digital channels, however a mclapp 4 bay or SBGH will out perform this coat hanger antenna. For me, the biquad worked better than the coat hanger antenna too.

I would skip this design and choose either the mclapp or SBGH.

I never built a mclapp 4 bay, but I did try a SBGH and would recommend it.
 

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for a higher gain antenna in the unfortunate circumstances I'm in, would I be better off with a SBGH, a mclapp 4 bay, or the Hoverman design from the PDF?
The SBGH like hkaye built in the photo is easier to build than a M4.
In a first floor apartment, you never know whats going on, so you may want to experiment with various models. Location, location, location is going to be key.
 

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Discussion Starter #16
hkaye said:
The PDF in your link is not a hoverman antenna - it's your typical coat hanger design. I built one of these as my first antenna - worked pretty good - I received quite a few digital channels, however a mclapp 4 bay or SBGH will out perform this coat hanger antenna. For me, the biquad worked better than the coat hanger antenna too.

I would skip this design and choose either the mclapp or SBGH.

Thanks for clarifying that!

Well, ruling that out leaves the mclapp 4 bay or the SBGH. I don't know if I've ever seen the GH style antennas built without a reflector. Is that even done?

If not, then the mclapp 4 bay would seem to be the route to go.

If that's the case, would the 9.5 x 9" M4 be the best bet for me? Or would a different sizing be better?
 

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Discussion Starter #17
300ohm said:
The SBGH like hkaye built in the photo is easier to build than a M4.
In a first floor apartment, you never know whats going on, so you may want to experiment with various models. Location, location, location is going to be key.

I understand. I don't mind the complexity of design for the M4, it's still relatively simple. The only complication is if I go with something other than wood for the mast and spacers.

And as I mentioned above, I don't even know if an SBGH can be easily done without a reflector, whereas the M4 can. Since space is an issue for me, that would suggest that the M4 might be the better idea.


If they can both be built without a reflector, than how do they compare with each other?
 

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Should be no problem making either one of those without a reflector.
They'll both work about the same.

Keep in mind though if ya really need some front-back ratio,
then building them with reflectors would be better to prevent interference
from the back side, and a bit more gain in the front. May not be an issue if ur just gonna keep it indoors, etc.
 

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TamSQ you will likely be faced with a multipath signal. using a directional antenna may help to maximize your strongest signal path. for indoor antennas people have constructed the antenna on one side of a piece of rigid polystyrene insulation and the reflector on the back side; it makes for a quick and easy build.
 

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Discussion Starter #20
Thanks. It looks like I'll try the M4 by itself at first, and add a reflector if it needs it.

Thank you, everyone, for your help! :)
 
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