Next Spring (2016) I will be installing
an old-fashioned (but newly manufactured)
Channel Master television antenna on a short tower
(maybe just a pole) with a rotator.
Here in Erie, Pennsylvania, under certain conditions I can receive
broadcasts from Erie and many of the cities that border close to
Lake Erie like Toronto and Waterloo (home
Blackberry), Canada and even Detroit. AM radio stations
are easily pulled in from the same areas, but FM does not do quite
so well. I plan to also integrate some form of FM antenna on the
installation. There is something insulting about paying for cable
or satellite TV and then having to suffer the deluge of commercials
as well (I have neither). Nobody likes
sitting through commercials, but at least if the programming is
being delivered at no cost, it is not unreasonable for the broadcast
companies to be paid by product sponsors.
Channel Master CM3020 Advantage 100 is my likely choice. It
is a 50-element combination HDTV/VHF/UHF/FM log periodic design
with an advertised range of up to 100 miles. VHF gain 8.6 dB and
UHF gain 9.5 dB, with a front-to-back ratio of 16 dB. I'll
need to do a little research on what height will be needed for decent
performance. Having the rotator with a good directional antenna
is key to good reception. Once everything is up and running I'll
post the project on RF Cafe.
Channel Master Yagi Antenna Ad
Tests Reveal Serious Mismatch in Stacked Yagis!
Z-Match, New Development, Achieves 100% Perfect Match To 300
Ohm Line, Single or Stacked •
Higher Gain On All Yagi Installations Accomplished By Adjustable
Impedance And Wider Spaced Elements.
Now! Stack Yagis without extra stacking bars!
Mismatch eliminated! Now Channel Master proudly introduces Z-Match
- a system that guarantees 100% perfect match in both single and
stacked Yagi installations.
Single bay Yagi perfectly matches 300 ohms because of wider spaced
elements. When Yagis are stacked, the center bars of the folded
dipoles are removed and used as half-wave connecting rods. This
reduces the impedance of each antenna, and automatically creates
a perfect 300 ohm match for the complete stacked Yagi array. The
Z-Match system, plus wide spacing, provide higher gain for Channel
Master Yagis, single or stacked. No extra stacking bars result in
Gain of Z-Match Yagi on Channel 4
How to Stack Yagis with 100 % Efficiency
New System Eliminates Mismatch; Provides Higher Gain For Yagis
Acting on the complaint of installers of all makes of Yagi antennas
that only a small additional gain was achieved in stacking, Channel
Master Laboratories engaged in a thorough research project during
the past summer. The engineers came up with the new Z-Match system,
and, like all important discoveries, it is relatively simple.
They noted that although all single Yagis claim to match 300
ohm line, they are stacked one-half-wave with 3/8" connecting rod
transformers spaced about 3" apart, with an impedance of 325 ohms.
Each Yagi's impedance, therefore, was stepped up to 350 ohms, with
the two in parallel totaling only 175 ohms. This meant a mismatch
of almost 2:1 when used with 300 ohm line. (Fig. 1 lower right)
Channel Master engineers reasoned that in stacking, the impedance
of' each single 300 ohm Yagi must be reduced in order for the total
stacked Yagi to match a 300 ohm line, as follows:
1. Let the single Yagi match 300 ohm line perfectly when used
2. Reduce Z (impedance) of each Yagi to 200 ohms for stacking.
3. Use 3/8" half-wave connecting rod transformers spaced at 3
4. These connecting rod transformers have an impedance of 350
5. These 350 ohm connecting rods transform each 200 ohm impedance
to 600 ohms.
6. The two 600 ohm impedances in parallel equal 300 ohms.
7. Therefore a perfect match is achieved in both single and stacked
antennas! (Fig. 2)
A) 3 element 1/2 wave folded dipole of single Yagi showing center
bar. B) 2 half-wave folded dipoles with center bars removed. C)
Center bars used as stacking rods.
The new Z·Match system automatically provides for lowering the impedance
of each Yagi when preparing it for stacking. A 600 ohm, 3 conductor
folded dipole (Fig. A) is used on the single Yagi to provide a perfect
300 ohm impedance. In stacking, the center bar is taken out of the
folded dipole which lowers the impedance to 200 ohms and leaves
a pair of 3/8" rods one-half-wave long (Fig. B). These are then
used as connecting rods and the result is a stacked Yagi which perfectly
matches a 300 ohm line (Fig. C). In order to provide a perfect 300
ohm impedance for the single Yagi, the crossarm had to be lengthened,
resulting in higher gain for the Z-Match single Yagi. The antenna
is wider spaced than most other commercial Yagis which use a half-wave
crossarm. Furthermore, the cost of extra connecting rods is completely
eliminated. Z-Match is an exclusive feature of Channel Master Yagi
antennas. Completely pre-assembled.
Channel Master Corp.
Napanoch Road, Ellenville, N. Y.
Write for complete technical literature.
Posted December 14, 2015