Any Benefit to a DBGH10n3 variant?

unclesam · May 7, 2011

Nikiml and 300ohm, would you expect improved reception from a DBGH10n3 over SB? My GH10n3 works great, but it peeves me that there are two peanut whistle UHF stations that I am unable to receive most of the time, 46 miles north in Washington, DC. I am preparing to build another GH10n3 that should be eaiser for most folks to build and hopefully will be lighter than my first. I also want to have it aimed upward to fit conditions at my location. It would not be that much harder for me to add a second vertical bay, without the NARODs and their 3 reflectors in the second. My current SBGH10n3 gets the two available VHF stations 24/7 even during widespread thunderstorms. If it is worth a try, am I correct that the two bays could share the same end reflector rod? Would the correct spacing of phasing lines still be about an inch above the active elements and an inch apart?

300ohm · May 7, 2011

would you expect improved reception from a DBGH10n3 over SB?

Yes, of course.

but it peeves me that there are two peanut whistle UHF stations that I am unable to receive most of the time, 46 miles north in Washington, DC. I am preparing to build another GH10n3 that should be eaiser for most folks to build and hopefully will be lighter than my first.

Since youre going to build another GH10n3 anyway, its worth a shot at ganging it. Height and location experiments on the SBGH10n3 may help, possibly even more than ganging.
Post your TVFool again and name those stations.

It would not be that much harder for me to add a second vertical bay, without the NARODs and their 3 reflectors in the second. My current SBGH10n3 gets the two available VHF stations 24/7 even during widespread thunderstorms. If it is worth a try, am I correct that the two bays could share the same end reflector rod?

Since your not going after additional vhf-hi gain, just more uhf gain, that should be fine. Wider spacing is required ganging for vhf-hi gain.

Would the correct spacing of phasing lines still be about an inch above the active elements and an inch apart?

Im still playing with phasing line design, but 1 inch above and and 2 inches apart is still about the best so far. Experiments with bending in the top to 1 inch, leaving the middle 2 inch spaced, may also be fruitful depending on the channels.
You could also try ganging with two baluns, two equal lengths of coax and a quality splitter used in reverse.
OR this Winegard SD 3700 300 Ohm TV Antenna Outdoor Coupler should be even better with less loss:
http://www.solidsignal.com/pview.asp?mc=03&p=SD-3700&d=Winegard-SD-3700-300-Ohm-TV-Antenna-Coupler-(SD3700)&c=Signal Combiners
(I dont like what they say "Joining two antennas can be a great alternative to a rotator" because if you point the antennas in different directions, youll lose gain from both. Which if the signals are strong enough, may be OK, but when ganging for max gain, you want both antennas pointing in the same direction.)

Also is the GH10n3 that you built/building have the same uhf dimensions as JEDs GH10 here ?
http://www.jedsoft.org/fun/antennas/dtv/gh.html

If not, which GH10n3 design did you build ? If different, Ill model it without the NARODs and NAROD reflectors to see if any impact on uhf.

nikiml · May 7, 2011

The model unclesam has built is this one: http://clients.teksavvy.com/~nickm/gh_n3_uV/gh10n3_9V7_15u0.html, and I am not sure if removing the VHF elements is a good idea...

300ohm · May 7, 2011

Removing the Top Hat NARODs and the 3 NAROD reflectors on that model produces this :

Raw Gain:

SWR:

NEC file:

Code:

CM GH10n3 average gain - uhf 15dBi/ vhf-hi 9.7dBi 
CM optimized by nikiml NAROD/NAROD Reflectors removed by 300ohm
CM covered by GPL v3 or later (http://www.gnu.org/licenses/gpl.txt)
CM see http://www.digitalhome.ca/forum/showpost.php?p=907404&postcount=2
CM Input file: input.nec
CM Sweep ranges:
CM R0 = (470, 6, 40) with target levels (15.5, 15.5)
CM R1 = (174, 6, 8) with target levels (10.5, 10.5)
CM SWR target: 2
CM Target function: max(max_swr_diff, .2*ave_max_gain_diff+.8*ave_gain_diff)
CM Score 0.657226
CE
GW	1	25	0	1.79864567	0	0	8.00685827	6.2082126	0.125
GW	2	23	0	8.00685827	6.2082126	0	2.52148425	11.6935866	0.125
GW	3	21	0	2.52148425	11.6935866	0	7.41087795	16.5829803	0.125
GW	4	13	0	7.41087795	16.5829803	0	12.1018819	16.5829803	0.125
GW	5	33	-3.111339	0.6624252	3.6782126	-3.111339	12.143323	

3.6782126	0.125
GW	6	41	-3.111339	1.7697795	9.0509646	-3.111339	15.656618	

9.0509646	0.125
GW	7	57	-3.111339	0.0777165	13.929362	-3.111339	19.813346	

13.929362	0.125
GW	8	65	-3.111339	1.7697795	21.898969	-3.111339	24.386437	

21.898969	0.125
GW	8	31	-3.111339	0.2899449	26.119988	-3.111339	11.068268	

26.119988	0.125
GW	21	25	0	-1.7986457	0	0	-8.0068583	6.2082126	0.125
GW	22	23	0	-8.0068583	6.2082126	0	-2.5214843	11.6935866	0.125
GW	23	21	0	-2.5214843	11.6935866	0	-7.410878	16.5829803	0.125
GW	24	13	0	-7.410878	16.5829803	0	-12.101882	16.5829803	0.125
GW	25	33	-3.111339	-0.662425	3.6782126	-3.111339	-12.14332	

3.6782126	0.125
GW	26	41	-3.111339	-1.76978	9.0509646	-3.111339	-15.65662	

9.0509646	0.125
GW	27	57	-3.111339	-0.077717	13.929362	-3.111339	-19.81335	

13.929362	0.125
GW	28	65	-3.111339	-1.76978	21.898969	-3.111339	-24.38644	

21.898969	0.125
GW	28	31	-3.111339	-0.289945	26.119988	-3.111339	-11.06827	

26.119988	0.125
GW	41	25	0	1.79864567	0	0	8.00685827	-6.2082126	0.125
GW	42	23	0	8.00685827	-6.2082126	0	2.52148425	-11.693587	0.125
GW	43	21	0	2.52148425	-11.693587	0	7.41087795	-16.58298	0.125
GW	44	13	0	7.41087795	-16.58298	0	12.1018819	-16.58298	0.125
GW	45	33	-3.111339	0.6624252	-3.678213	-3.111339	12.143323	-

3.678213	0.125
GW	46	41	-3.111339	1.7697795	-9.050965	-3.111339	15.656618	-

9.050965	0.125
GW	47	57	-3.111339	0.0777165	-13.92936	-3.111339	19.813346	-

13.92936	0.125
GW	48	65	-3.111339	1.7697795	-21.89897	-3.111339	24.386437	-

21.89897	0.125
GW	48	31	-3.111339	0.2899449	-26.11999	-3.111339	11.068268	-

26.11999	0.125
GW	61	25	0	-1.7986457	0	0	-8.0068583	-6.2082126	0.125
GW	62	23	0	-8.0068583	-6.2082126	0	-2.5214843	-11.693587	0.125
GW	63	21	0	-2.5214843	-11.693587	0	-7.410878	-16.58298	0.125
GW	64	13	0	-7.410878	-16.58298	0	-12.101882	-16.58298	0.125
GW	65	33	-3.111339	-0.662425	-3.678213	-3.111339	-12.14332	-

3.678213	0.125
GW	66	41	-3.111339	-1.76978	-9.050965	-3.111339	-15.65662	-

9.050965	0.125
GW	67	57	-3.111339	-0.077717	-13.92936	-3.111339	-19.81335	-

13.92936	0.125
GW	68	65	-3.111339	-1.76978	-21.89897	-3.111339	-24.38644	-

21.89897	0.125
GW	68	31	-3.111339	-0.289945	-26.11999	-3.111339	-11.06827	-

26.11999	0.125
GW	100	11	0	-1.7986614	0	0	1.79864567	0	0.10843701
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	2.49e7	0
EX	0	100	6	0	1	0
GN	-1
FR	0	1	0	0	800	0

Not so different for UHF than the GH10n3 here http://clients.teksavvy.com/~nickm/gh_n3_uV/gh10n3_9V7_15u0.html , so he should be OK. Sounds like his vhf-hi stations are pretty strong.

nikiml · May 7, 2011

When ganging two antennas, aren't they supposed to be identical?

stampeder · May 7, 2011

Ideally, yes, or else there is a world of debugging that may be required.

300ohm · May 7, 2011

When ganging two antennas, aren't they supposed to be identical?

Yes, or very close, for the same frequency range for maximum gain.

nikiml · May 8, 2011

I thought that the phases are important (and not the gain) and that they have to match at the combining point so that there is no cancellation.

Is it possible to predict the phase mismatch of two different antennas?

300ohm · May 8, 2011

Is it possible to predict the phase mismatch of two different antennas?

Not sure, but somehow I think it is. And yes, its all in the combining.

In Unclesams case, hes going to stack nearly identical uhf sections together. The vhf-hi effect on the uhf section of the GH10n3 isnt all too great. (but more than a GH10n2 would be)

Running a model of what he proposes to do with 2 EX cards theoretically looks pretty good. Vhf-hi gain looks to remain about the same as a single GH10n3. So with good combining, he should be in great shape if all that is required for those stations is a bit more gain. On the other hand, the signal just may not be there.

Code:

CM GH10n3 average gain - uhf 15dBi/ vhf-hi 9.7dBi 
CM optimized by nikiml
CM Stack with one GH10n3 and one GH10n3 NARODs and NAROD reflectors removed
CM Using 2 EX cards by 300 ohm
CM covered by GPL v3 or later (http://www.gnu.org/licenses/gpl.txt)
CM see http://www.digitalhome.ca/forum/showpost.php?p=907404&postcount=2
CM Input file: input.nec
CM Sweep ranges:
CM R0 = (470, 6, 40) with target levels (15.5, 15.5)
CM R1 = (174, 6, 8) with target levels (10.5, 10.5)
CM SWR target: 2
CM Target function: max(max_swr_diff, .2*ave_max_gain_diff+.8*ave_gain_diff)
CM Score 0.657226
CE
GW	1	25	0	1.7987008	26.119988	0	8.0069134	32.3282006	0.125
GW	2	23	0	8.0069134	32.3282006	0	2.52153938	37.8135746	0.125
GW	3	21	0	2.52153938	37.8135746	0	7.41093308	42.7029683	0.125
GW	4	13	0	7.41093308	42.7029683	0	12.101937	42.7029683	0.125
GW	5	33	-3.111339	0.6624803	29.798201	-3.111339	12.1433778	29.798201	0.125
GW	6	41	-3.111339	1.7698347	35.170953	-3.111339	15.6566728	35.170953	0.125
GW	7	57	-3.111339	0.0777717	40.04935	-3.111339	19.8134018	40.04935	0.125
GW	8	65	-3.111339	1.7698347	48.018957	-3.111339	24.3864918	48.018957	0.125
GW	8	31	-3.111339	0.29	52.239976	-3.111339	11.0683228	52.239976	0.125
GW	11	13	-3.1113386	7.27890946	45.8407282	0	7.27890946	43.1754093	0.125
GW	12	13	0	7.27890946	43.1754093	0	11.9699134	43.1754093	0.125
GW	21	25	0	-1.7985905	26.119988	0	-8.0068031	32.3282006	0.125
GW	22	23	0	-8.0068031	32.3282006	0	-2.5214291	37.8135746	0.125
GW	23	21	0	-2.5214291	37.8135746	0	-7.4108228	42.7029683	0.125
GW	24	13	0	-7.4108228	42.7029683	0	-12.101827	42.7029683	0.125
GW	25	33	-3.111339	-0.66237	29.798201	-3.111339	-12.14327	29.798201	0.125
GW	26	41	-3.111339	-1.769724	35.170953	-3.111339	-15.65656	35.170953	0.125
GW	27	57	-3.111339	-0.0776614	40.04935	-3.111339	-19.813289	40.04935	0.125
GW	28	65	-3.111339	-1.769724	48.018957	-3.111339	-24.38638	48.018957	0.125
GW	28	31	-3.111339	-0.28989	52.239976	-3.111339	-11.06821	52.239976	0.125
GW	31	13	-3.1113386	-7.2787992	45.8407282	0	-7.2787992	43.1754093	0.125
GW	32	13	0	-7.2787992	43.1754093	0	-11.969803	43.1754093	0.125
GW	13	41	-3.111339	-7.2788032	45.840728	-3.111339	7.2789095	45.840728	0.125
GW	15	93	-12.8872	-16.077069	45.176453	-12.8872	16.0771968	45.176453	0.125
GW	41	25	0	1.7987008	26.119988	0	8.0069134	19.9117754	0.125
GW	42	23	0	8.0069134	19.9117754	0	2.52153938	14.4264014	0.125
GW	43	21	0	2.52153938	14.4264014	0	7.41093308	9.5370077	0.125
GW	44	13	0	7.41093308	9.5370077	0	12.101937	9.5370077	0.125
GW	45	33	-3.111339	0.6624803	22.441775	-3.111339	12.1433778	22.441775	0.125
GW	46	41	-3.111339	1.7698347	17.069023	-3.111339	15.6566728	17.069023	0.125
GW	47	57	-3.111339	0.0777717	12.190626	-3.111339	19.8134018	12.190626	0.125
GW	48	65	-3.111339	1.7698347	4.22102	-3.111339	24.3864918	4.221019	0.125
GW	48	31	-3.111339	0.29	0	-3.111339	11.0683228	0	0.125
GW	51	13	-3.1113386	7.27890946	6.3992478	0	7.27890946	9.0645667	0.125
GW	52	13	0	7.27890946	9.0645667	0	11.9699134	9.0645667	0.125
GW	61	25	0	-1.7985905	26.119988	0	-8.0068031	19.9117754	0.125
GW	62	23	0	-8.0068031	19.9117754	0	-2.5214291	14.4264014	0.125
GW	63	21	0	-2.5214291	14.4264014	0	-7.4108228	9.5370077	0.125
GW	64	13	0	-7.4108228	9.5370077	0	-12.101827	9.5370077	0.125
GW	65	33	-3.111339	-0.66237	22.441775	-3.111339	-12.14327	22.441775	0.125
GW	66	41	-3.111339	-1.769724	17.069023	-3.111339	-15.65656	17.069023	0.125
GW	67	57	-3.111339	-0.077661	12.190626	-3.111339	-19.81329	12.190626	0.125
GW	68	65	-3.111339	-1.7697242	4.221019	-3.111339	-24.386379	4.221019	0.125
GW	68	31	-3.111339	-0.2898902	0	-3.111339	-11.068209	0	0.125
GW	71	13	-3.1113386	-7.2787992	6.3992478	0	-7.2787992	9.0645667	0.125
GW	72	13	0	-7.2787992	9.0645667	0	-11.969803	9.0645667	0.125
GW	53	41	-3.111339	-7.2788032	6.399248	-3.111339	7.2789095	6.399248	0.125
GW	55	93	-12.8872	-16.077069	7.063523	-12.8872	16.0771968	7.063523	0.125
GW	16	105	-12.88721	-18.19991	26.119988	-12.88721	18.200032	26.119988	0.125
GW	100	11	0	-1.7986063	26.119988	0	1.7987008	26.119988	0.10843701
GW	5000	25	0	1.79870107	-26.12497	0	8.00691367	-19.91676	0.125
GW	5001	23	0	8.00691367	-19.91676	0	2.52153965	-14.431383	0.125
GW	5002	21	0	2.52153965	-14.431383	0	7.41093335	-9.54199	0.125
GW	5003	13	0	7.41093335	-9.54199	0	12.1019373	-9.54199	0.125
GW	5004	33	-3.111339	0.662481	-22.44677	-3.111339	12.143378	-22.44677	0.125
GW	5005	41	-3.111339	1.7698349	-17.07401	-3.111339	15.656673	-17.07401	0.125
GW	5006	57	-3.111339	0.077772	-12.19561	-3.111339	19.813401	-12.19561	0.125
GW	5007	65	-3.111339	1.7698349	-4.226	-3.111339	24.386492	-4.226	0.125
GW	5009	25	0	-1.7985903	-26.12497	0	-8.0068029	-19.91676	0.125
GW	5010	23	0	-8.0068029	-19.91676	0	-2.5214289	-14.431383	0.125
GW	5011	21	0	-2.5214289	-14.431383	0	-7.4108226	-9.54199	0.125
GW	5012	13	0	-7.4108226	-9.54199	0	-12.101827	-9.54199	0.125
GW	5013	33	-3.111339	-0.66237	-22.44677	-3.111339	-12.14327	-22.44677	0.125
GW	5014	41	-3.111339	-1.769725	-17.07401	-3.111339	-15.65657	-17.07401	0.125
GW	5015	57	-3.111339	-0.077662	-12.19561	-3.111339	-19.8133	-12.19561	0.125
GW	5016	65	-3.111339	-1.769725	-4.226	-3.111339	-24.386386	-4.226	0.125
GW	5018	25	0	1.79870107	-26.12497	0	8.00691367	-32.33318	0.125
GW	5019	23	0	8.00691367	-32.33318	0	2.52153965	-37.81856	0.125
GW	5020	21	0	2.52153965	-37.81856	0	7.41093335	-42.70795	0.125
GW	5021	13	0	7.41093335	-42.70795	0	12.1019373	-42.70795	0.125
GW	5022	33	-3.111339	0.662481	-29.80317	-3.111339	12.143378	-29.80317	0.125
GW	5023	41	-3.111339	1.7698349	-35.17597	-3.111339	15.656673	-35.17597	0.125
GW	5024	57	-3.111339	0.077772	-40.05437	-3.111339	19.813401	-40.05437	0.125
GW	5025	65	-3.111339	1.7698349	-48.02397	-3.111339	24.386492	-48.02397	0.125
GW	5026	31	-3.111339	0.29	-52.245	-3.111339	11.0683234	-52.24497	0.125
GW	5027	25	0	-1.7985903	-26.12497	0	-8.0068029	-32.33318	0.125
GW	5028	23	0	-8.0068029	-32.33318	0	-2.5214289	-37.81856	0.125
GW	5029	21	0	-2.5214289	-37.81856	0	-7.4108226	-42.70795	0.125
GW	5030	13	0	-7.4108226	-42.70795	0	-12.101827	-42.70795	0.125
GW	5031	33	-3.111339	-0.66237	-29.80317	-3.111339	-12.14327	-29.80317	0.125
GW	5032	41	-3.111339	-1.769725	-35.17597	-3.111339	-15.65657	-35.17597	0.125
GW	5033	57	-3.111339	-0.077662	-40.05437	-3.111339	-19.8133	-40.05437	0.125
GW	5034	65	-3.111339	-1.769725	-48.02397	-3.111339	-24.38639	-48.02397	0.125
GW	5035	31	-3.111339	-0.28989	-52.24497	-3.111339	-11.06822	-52.24497	0.125
GW	5036	11	0	-1.798606	-26.12497	0	1.79870107	-26.12497	0.10843701
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	2.49e7	0
EX	0	100	6	0	1	0
EX	0	5036	6	0	1	0
GN	-1
FR	0	1	0	0	800	0

These are just theoretical maximums. The proof would be in the combining. I think the Winegard SD 3700 would be the safe way to go.
I may get one of them just to see whats inside, heh. I already have some Channel Master 300 ohm indoor couplers, (300ohm in and out) so it would be nice to compare.
Also I think with the Winegard SD 3700, he'll have to observe the polarity of the 300 ohm twin lead, just like observing the polarity of the baluns on a 2 way splitter coupling.

nikiml · May 9, 2011

how difficult is to aim such antennas with less than 10 deg vertical beamwidth?

300ohm · May 9, 2011

Yeah, its going to be pretty tight. Thats the downside of higher gain.

unclesam · May 24, 2011

Thanks for the Useful Insights

Thanks for the suggestions re: DB GH10n3, with the second bay not having NARODs and the 3 NAROD reflectors. Sounds like my best strategy is to experiment with elevation aiming using existing GH10n3, partly to make up for the mast currently causing antenna to look slightly downward. What is driving me is that sometimes on some days I can get the remaining pipsqueak stations I seek. If re-aiming the current antenna does not bring them in, then I will build a DB. I have designed a single spine version that does not require precision drilling of plastic pipe; a simple jig is used to attach all the elements in their correct locations and orientations. I have also worked out a way to grip and attach reflectors made from fiberglas rod wrapped with metal tape. I would try stainless steel tape, even though its conductivity is lower than copper or aluminum, for several reasons. I already have a roll of stainless steel tape, and the metal is quite strong and tough. I stuck a tab of it to a clean vertical metal surface outdoors over five years ago, in a location exposed to direct mid-Atlantic US weather. The sample still looks like new and shows no sign of coming unstuck. I do not think the aluminum tape sold in home centers would be as durable outdoors as the stainless steel. My primary concern about building a DB has been connecting the bays together, and it appears that the Winegard SD 3700 provides the answer.

300ohm · May 24, 2011

and it appears that the Winegard SD 3700 provides the answer.

I posted some details on my SD 3700 here, starting on post 1312

Any Benefit to a DBGH10n3 variant?

unclesam

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300ohm

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nikiml

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