It should be noted first and foremost that I am not an antenna design expert. I have tried to explain how this antenna and the Gray-Hoverman antenna work and how, but tried to leave out the real technical details to others. I have just taken what has been designed, modeled and successfully used in the field, and applied it to my situation. If you want greater understanding of how this antenna and the Gray-Hoverman works, please goto digitalhome.ca, and there is a whole forum section dedicated to OTA antenna design. Formidable users are 300ohms, stampeder and mclapp among others.
The Mclapp-4 is another type of UHF antenna. It is designed on the bowtie philosophy. There is the simple DIY bowtie antenna that someone has made a YouTube video of, buy bending some coat hangers which forms the elements, then connecting them together with wiring called phase lines. This design, though has worked very well for people, there are a few flaws. The elements, or whiskers are only 7", which will work for many higher frequencies, but misses the entire UHF spectrum. The other big issue with this simple design is if looking at the the perspective of the balun, the signals from both sides of the elements will be out of phase, so lose of signal integrity.
Enter the Mclapp. The Mclapp was designed and modeled in 4nec by an individual nic'd "mclapp" that frequents the digithome.ca site. The big differences is that the base unit uses 9.5" whiskers, and the phase line at each end is twisted. The longer whiskers allows the antenna to pick up a wider band of UHF frequencies, while twisting of the phase lines keeps the signal in phase as seen by the balun.
So why build this antenna since I already have built the Single-Bay Gray-Hoverman? Supposedly the Mclapp is slightly better at picking up the upper UHF frequencies. The Gray-Hoverman starts to decline in gain with going above channel 50. Since there are a few channels I want to try and get that are in the upper region of the UHF band, I may have better luck with the Mclapp. The second reason, and I have to double check this is that the Mclapp is also slightly better at getting VHF-Hi channels, and analog signals, while the Gray-Hoverman is supposed to be slightly better at picking up the low to mid UHF frequencies. So the plan is to use the Mclapp, pointed at the CNTower to get the Canadian broadcasts, then build on the Gray-Hoverman and make it a dual bay, pointed towards the South of East to try and get some of the fringe Buffalo channels, CHCH and SunTV.
The current build of my Mclapp is a 4-bay bowtie. It doesn't have a reflector yet. I'm trying to find a cheap screen...something as simple as an old oven rack from a trashed stove. The bowtie elements are cut coat hangers, the phase-lines are the left-over ground wiring from the 2-10AWG wire I picked up for building the elements of the Gray-Hoverman. This wire is copper at 14AWG. I used some of the self tapping screws that I used in the Gray-Hoverman design, as well as the extra PVC 3/4" conduit. I only had to pickup some more PVC 3/4" "T"'s. The feed/balun was from the GH project, which I soldered to the mid-point of the phase lines. The total cost of the antenna is well under $20.
I used the basic design details that can be found here:
Specifically the 4 bay 9 1-2 element layout.pdf and the 4 bay 9 inch phase line.pdf
The basic diagram is shown below:
Excuse the poor showing of twisting the phase wiring. It's a little hard to show the overlap, but basically when twisting, I tried to keep the distance between the two phase wires at a constant...approx 1.25".
I will be adding photos soon. I'm going to be wiring in the balun tonight so hopefully I'll be able to get some real values.
Here are some pics of the actual build:
This antenna was used primarily as an experimental to introduce me to the world of OTA. I was intending on using this antenna for Canadian broadcasts from Toronto, but learned that mixing antenna types was not a very good idea. For my practical application, I'm using two Gray-Hoverman antennas in my attic. Please view that page for the latest details on my OTA quest. This antenna will now be relegated to being used as a demonstration model for friends and family to try out. If I do end up using it, I will point it west bound to pickup stations from London and beyond and try and see what happens when three antennas are combined...even consider having my own "Antenna Farm".
I soldered the balun to the phase lines last night, and then put it up in the livingroom to try out. The difference between testing this to testing the Gray-Hoverman was that I opened the blind so I could maximize any signals coming into the house. Well pointing it in different directions I was able to pick up the standard CHCH (11.1), SunTV (15.1), CW23 (23.1), CTS (36.1) and WNYB (26.1, plus 26.2). This was the first time I was able to get 26.2, from the livingroom. In addition, I was able to get CBC (5.1), though this depended on the antenna placement. The most exciting thing was that I pointed the antenna towards the SE and picked up ABC (7.1). This is the first time that I have been able to receive one of the real big American broadcasts. Yeah, I did pick up PBS with the GH on the second floor of my home, but ABC is one of the reasons I'm trying to do all this, so it was nice to see.
So is this antenna better than the Gray-Hoverman? Some would say yes as I picked up ABC which I haven't been able to do with the Hoverman, but the test conditions were different. The Mclapp-4 I was able to prop up and lean it against a tri-pod for better clearance. The Gray-Hoverman always just sat on the floor, leaning too far back, so it never got a clear signal. The other thing was that last night, I raised the livingroom blinds to hopefully get better signals (which was proven by getting ABC), which I never did with the Hoverman. I still feel that a dual-bay GH will work wonders in getting those American broadcasts (ABC/NBC/PBS/CBS and Fox), and this antenna will be very successful in getting the Canadian feeds I'm trying to get (CBC/CityTV/Omni1/2/TVO/CTV anc Global). I'm still debating whether to add a reflector or not.
I tested the antenna out some more on the second floor of the house. Moving it around to various locations, I was able to scan in most of the above listed channels, PBS again (like with the Hoverman), and somehow scanned in CBS (4.1), though it wasn't watchable. Reason why that is confusing is that I had the antenna on the opposite side of the house to where I thought I should have picked it up, and the antenna was backwards, so the backside of the antenna was getting the signal. So it is really confusing me as to how I has able to get it period, meanwhile ABC is in the same direction, yet I wasn't able to scan in that channel.
The more dissapointing thing was that other than CBC, I haven't been able to get any other channel transmitted from the CN Tower clearly. It clearly can get a signal on most of them, but it is too weak to lock on anything. So if I still can't pick anything up in the attic, I still have a couple of options: 1) to throw on a grid reflector, and 2) been looking at an in-line line amp like the KT-100G from Kitz Technologies. If worst comes to worst, I can temporarily use this antenna pointed SE and pickup CHCH, SunTV, CW23, ABC, and hopefully CBS and PBS until I get the dual-bay Gray Hoverman built.
After unsuccessfully testing a DBGH last night, I went back and tested the M4 tonight. I'm still looking for a cheap reflector to use with this antenna, but decided to see what I could pull in again. The test conditions were good: outside temperature was around 10 degree Celsius, and it appeared to be a little overcast. The test location was the dreaded livingroom again, with the antenna pointing in the SE direction. Tonight though it was a very successful test run. When I loaded WatchHDTV, the first channel to load was CBS (4.1)...well this is the signal results:
The signal was good, and had a picture. This was the first time I have ever been able to get a good video feed from this channel. I then turned to ABC (7.1) which I have gotten in the past from this test location. Here is the scren cap:
I then went into the WatchHDTV setup and added NBC, PBS, and tried Fox. I was successful at getting NBC (2.1, 2.2, 2.3) and PBS (17.1, 17.2 and 17.3). This is the first time I was able to get PBS from this test location, and the very first time...EVER in getting NBC. Below are the screen caps of the first sub-channel of each:
I also took a capture of CW23, even though I have repeated successfully received this channel in the past:
In additon were the usual CHCH (11.1), SunTV (15.1), CTS (36.1, 36.2) and WNYB (26.1, 26.2)
The attempt at getting Fox:
A total of 15 digital channels (2.1, 2.2, 2.3, 4.1, 7.1, 11.1, 15.1, 17.1, 17.2, 17.3, 23.1, 26.1, 26.2, 36.1, 36.2) tonight. A very successful test indeed. Tonight was a good night, and much needed after flopping with the DBGH tryout.
I finally caved and picked up a roll of 1"x2" galvanized steel mesh for a reflector and have been testing my M4 with a reflector for the last little while. The reflector steel is 14AWG and measures 36" wide by 40" high. Though lately I've been pretty successful and consistent in getting ABC, NBC, CBS, CW23, CHCH and SunTV (along with CTS) from the living room, I was able to get this antenna up on the second floor tonight. In total from two different locations, I was successful in getting NBC-HD (Universal Sports and RTV) 2.1, 2.2, 2.3, CBS-HD 4.1, ABC-HD 7.1, CHCH-DT 11.1, SunTV 15.1, PBS-HD (SD and Think) 17.1, 17.2, 17.3, CW23 23.1, WNYB 26.1, 26.2, CTS 36.1, 36.2. But along with this extra height, in this same direction I was able to get Fox-HD (and SD) 29.1, 29.2, and MyTV-HD (and SD) 49.1, 49.2 (first time for both channels). With the antenna facing towards the CNTower, I was able to get CBC-HD 5.1 and OMNI2 44.1 (first time for this channel). In analog I've picked up 9, 11, 13, 19, 28, 31, 36, 41, 45, 47, 57, 69, though only a handful were actually watchable. So in total I've been able to pickup 21 digital (including HD) channels, and 12 analog channels. This antenna is working so well in picking up stations in the Buffalo direction, that I may consider using this antenna in the attic for that use, and use the GH to get TO stations, which are proving to be actually pretty difficult stations to get. Though tonight was a pretty successful test. Below is some further signal measurements on some additional channels.
In the other direction was the first time I've been able to pick up Fox from Buffalo, though it wasn't a steady picture
So now I'm pretty convinced that I will get pretty decent results, at least Buffalo bound, once the antenna is mount in the attic. Now I have to put a mesh reflector on the GH and verify what it can pickup...and to finally figure out once and for all, which is the better antenna (if any).
Here are some pics of the M4 with reflector:
This antenna has been delegated to now being my demonstration antenna. It has performed very well for me, but for my application, and in using multiple antennas (or is it anteni?), I have chosen to use two Gray-Hoverman single bay types, so at least they are very similar in design. The M4 is a great antenna, which is very easy to build, and I am very pleased with its performance. Hat's off to MClapp over at digitalhome.ca for his great design.
A friend has been borrowing this antenna for the last little while, so I haven't had much time to play with it. Now that I have it back, I'm going to be showing a few people the capabilities of OTA, then I'm going to place this antenna in the attic. I'm going to experiment by replacing the SBGH that is facing Toronto with the M4 to see if I can pick up the elusive City and Global channels. If it does, and both antennas interact positively, then I may end up using this build in a more permanent setup. This will mean replacing the whisker elements with copper bowties, as the steel coat hangers will most likely rust up in very little time when in the attic. Just from the simple transferring via car to my buddies place, I have noticed that the whiskes are oxidizing.
The Gray-Hoverman that was used for Toronto reception (or this antenna if I don't use it for TO), will then be experimented with to see if I can pick up anything from Erie, or London way, or I may gang it with the other Gray-Hovermand towards Buffalo, and use it as a horizontal 2-bay GH, and see if I can get more gain towards Buffalo.
Started to convert the whiskers over from the coat hangers to 10AWG copper wire. It was collecting dust at my parents house, and it was just enough for this job. I've cut and bent all the lengths. I just have to install them to the antenna. Going to be using this to demo over at a friend's house soon, so I want it in top shape. Pictures are yet to come.