I'm a ham radio operator for almost 20 years now, and one thing I have always found very interesting are antennas. Spent a lot of time reading about them and lots of time building them. Far from an expert, but here goes my attempt at "antennas 101"..
All things considered, the Winegard Sensar performs very well. It *is* a compromise antenna for a few reasons.
When it comes to antennas, size matters. The length/size of antenna is directly proportional to the frequencies it is intended to receive (or transmit). Along that line, there is an optimal size for any antenna, anything smaller is a compromise, and generally a big compromise at that.
The amplfier in the sensar head "helps" make up for some of the missing size, however, amplifiers will amplify noise just as well as they will signal - another compromise. It is also impossible to amplify what is not already there.
Anyone who ever used an SWR meter to tune an old CB antenna will understand the basic size principle.
Antennas can be omnidirectional or directional. The radio antenna on the roof of a Sunline is an omnidirectional antenna. This means that it will receive from all directions equally.
The Sensar TV antenna on our trailers is considered directional. Directional means that the antenna will provide the strongest (best) reception in one (or two) directions. Basically, a directional antenna hears really well in one direction, much like what happens if you cup your hand around your ear. You hear really good in one direction, and barely hear in the other. The phenomenon is called antenna "gain" and explains why you need to turn the antenna for the best reception.
The more directional an antenna is, the more "gain" it will have, and the better it will hear in that one direction. It will also need to be pointed more precisely. What the wingman add-on aims to do is make the Sensar *more directional*. If you could draw out the way the Sensar "hears," it would look very much like a figure 8, with the strongest reception occuring perpendicular to the two "bat wing" elements. Once the wingman is added, the pattern would look egg shaped, perpendicular to the elements, but pointed in the direction of the wingman.
I won't claim this doodle is 100% technically accurate, but it should help folks understand the basic principles at play here:
The next big factor at play here is the frequencies involved. The digital TV signals are pretty much in the same place ("VHF" and "UHF") that the old analog signals were. As you go higher in frequency (from VHF to UHF), the signals become what is called "line of sight." It literally means the way it sounds - if you can't "see" it, you will have a hard time receiving it. This is why antenna height is paramount. "See" is in quotes, because it is not 100% literal - things like reflections come into play, but it's darn close.
One other catch with the wingman - due to it's size, you can really only expect it to help on stations using the UHF spectrum. The good news is that in most places the transition to digital moved most stations to the UHF portion of the spectrum. The bad news is that UHF is extremely "line of sight". Another catch - with the move to digital, the channel numbers are an arbitrary reference only and no longer indicate the frequency the TV station is transmitting on. If you want to know that (and most people dont care or even know why they might want to care), you'd have to go look it up.
The final piece of bad news is that as part of the move to digital, a lot of TV stations were forced to reduce their transmit power. This obviously decreases range. The general explanation was that the digital signal would be less affected by the reduced power, however, people's complaints indicate otherwise.
As far as what you can do for a better signal, that's pretty simple:
#1 - Height. The higher the antenna, the better the chances of receiving a signal. Unfortunately, traveling with a 20+ foot mast is probably not very practical.
#2 - "Better" (bigger) antenna. A bigger antenna will increase your chances of getting a good signal. If you are in an area that has moved to the UHF bands for all the digital stations, that's potentially good news - a UHF antenna is much smaller physically than a UHF one.
#3 - Take the time to point the antenna well. A lot of the newer digital TVs have a signal meter buried somewhere in the setup menu. If you can bring that up, you will be able to get a good indication of signal strength as you turn the little knob.
Ideally you would have a very tall mast with quite a large antenna on the top. Talk about adding set-up time
One final note: Don't let someone fool you into needing a "digital antenna." That is, quite frankly, a big crock of you know what. An antenna is an antenna. It does not care what form of modulation is being used (digital, analog, or other).
Hopefully this helps somehow and has not confused anybody further.
- Frank
