Fractal TV Antenna Research & Development - Page 20 - Canadian TV, Computing and Home Theatre Forums

fractalguy · 2012-05-17, 03:21 PM

Hi 300 ohmer--

Can you be a bit more forthcoming on your results? Why not put them up on a website so we can compare them? I'd love to see them and critique them for you.

Best wishes,
Nathan Cohen

300ohm · 2012-05-17, 11:44 PM

For the GH, my results are in posts 15 and 17 of this thread. (luckily, those pictures werent deleted when ImageShack changed their terms of service.

)

Thanks.

300ohm · 2012-05-24, 08:59 AM

Quote:

Can you be a bit more forthcoming on your results?

For the bowtie fractalization analysis, I chose a common DB2a 2 bay with its reflector removed, (which is similar to HTPC-Diy's in post #283 of this thread, also very commonly seen on YouTube) as the reference bowtie to keep things simple. A long while ago, I did a similar test with a 4 bay reflectorless bowtie and got the same bottom line results.

Size comparison pictures:

Pictured from left to right are:
The original DB2a,
The fractalized version of it,
The open end whisker version of it with the whisker length span of the fractalized version,
And the closed end whisker version of it with the whisker length span of the fractalized version.

The original DB2a has a whisker length of 6.188 inches and when fractalized /4 becomes 5.282 inches in length. (6.188 / 4 = 1.547) (1.547 + (sqrt 2 * 1.547) + 1.547 = 5.282)
Distances between bays, phasing line distances and wire size (6 ga) were held constant for all four NEC models.

Net Gain Comparisons:

.xls file of above here: http://www.wuala.com/300ohm/Document...mparisons.xls/

Net Gain is Raw Gain, as generated by the 4nec2 program, minus the SWR mismatch loss of the antenna.

As you can see, the fractalized version of the DB2a is a bit overall better than the shortened to 5.282" open end whisker version, but no where as good as the shortened to 5.282" closed end whisker version. It appears the shortened to 5.282" closed end whisker version, (which takes up as much space as the fractilized version and is easier to make too) is even superior to the original sized DB2a on most channels. This kind of makes sense since the whisker bowties are representations of a cone. The closer the bowtie comes to a cone, the better.
In other analyses, Ive found that by using a closed end bowtie instead of an open end whisker bowtie, the closed end bowtie can be a good 1/2 inch shorter for the same frequency range.
Unlike the GH, there doesnt seem to be any practical benefit to fractalizing the bowtie, at least not in the way its typically done as in the first picture above.

Reference NEC files to follow.

Quote:

I'd love to see them and critique them for you.

Any ideas Dr Cohen ?

I would think square shaped or even Mandelbrot set shaped fractals would respond the same way due to the nature of the bowtie.

300ohm · 2012-05-25, 01:31 AM

The DB2a Original No Reflector NEC file, from Ken Nist's measurements. The slightly swept forward whiskers were also flattened.

Raw Gain and SWR:

NEC file:

Code:

CM DB2 :  AntennasDirect DB-2, converted with 4nec2 on 17-May-12 23:58
CM reflector removed, whiskers flattened
CM AGT= 1.0 (0db) at 585 mhz, AutoSeg = 20
CE
GW	1	7	4	0.85	0	4	0.85	3.7	0.08
GW	2	1	4	0.85	3.7	4	0.85	4.2	0.08
GW	3	13	4	0.85	3.7	4	6.8	1.9	0.08
GW	4	13	4	0.85	4.2	4	6.8	5.9	0.08
GW	5	7	4	-0.85	0	4	-0.85	3.7	0.08
GW	6	1	4	-0.85	3.7	4	-0.85	4.2	0.08
GW	7	13	4	-0.85	3.7	4	-6.8	1.9	0.08
GW	8	13	4	-0.85	4.2	4	-6.8	5.9	0.08
GW	9	7	4	0.85	0	4	0.85	-3.7	0.08
GW	10	1	4	0.85	-3.7	4	0.85	-4.2	0.08
GW	11	13	4	0.85	-3.7	4	6.8	-1.9	0.08
GW	12	13	4	0.85	-4.2	4	6.8	-5.9	0.08
GW	13	7	4	-0.85	0	4	-0.85	-3.7	0.08
GW	14	1	4	-0.85	-3.7	4	-0.85	-4.2	0.08
GW	15	13	4	-0.85	-3.7	4	-6.8	-1.9	0.08
GW	16	13	4	-0.85	-4.2	4	-6.8	-5.9	0.08
GW	17	3	4	-0.85	0	4	0.85	0	0.08
GS	0	0	0.0254		' All in in.
GE	0
LD	5	0	0	0	2.5e7	0
EX	0	17	2	0	1	0
GN	-1
FR	0	1	0	0	585	0

300ohm · 2012-05-25, 01:49 AM

DB2a Fractalized /4 NEC file.

Raw Gain and SWR charts:

NEC file:

Code:

CM DB2 :  AntennasDirect DB-2, converted with 4nec2 on 17-May-12 23:58
CM reflector removed, whiskers flattened  Fractalized
CM AGT= 1.0 (0db) at 585 mhz, AutoSeg = 20
CE
GW	100	7	4	0.85	0	4	0.85	3.7	0.08
GW	101	1	4	0.85	3.7	4	0.85	4.2	0.08
GW	102	3	4	0.85	3.7	4	2.3375	3.25	0.08
GW	103	3	4	4.4317652	2.61644078	4	5.91251024	2.1684843	0.08
GW	104	3	4	0.85	4.2	4	2.3375	4.625	0.08
GW	105	3	4	4.4413144	5.22608983	4	5.9510993	5.65745694	0.08
GW	106	7	4	-0.85	0	4	-0.85	3.7	0.08
GW	107	1	4	-0.85	3.7	4	-0.85	4.2	0.08
GW	108	3	4	-0.85	3.7	4	-2.3375	3.25	0.08
GW	109	3	4	-4.4317652	2.61644078	4	-5.9125102	2.1684843	0.08
GW	110	3	4	-0.85	4.2	4	-2.3375	4.625	0.08
GW	111	3	4	-4.4413144	5.22608983	4	-5.9288112	5.65108891	0.08
GW	112	7	4	0.85	0	4	0.85	-3.7	0.08
GW	113	1	4	0.85	-3.7	4	0.85	-4.2	0.08
GW	114	3	4	0.85	-3.7	4	2.3375	-3.25	0.08
GW	115	3	4	4.4317652	-2.6164408	4	5.91251024	-2.1684843	0.08
GW	116	3	4	0.85	-4.2	4	2.3375	-4.625	0.08
GW	117	3	4	4.4413144	-5.2260898	4	5.92881117	-5.6510889	0.08
GW	118	7	4	-0.85	0	4	-0.85	-3.7	0.08
GW	119	1	4	-0.85	-3.7	4	-0.85	-4.2	0.08
GW	120	3	4	-0.85	-3.7	4	-2.3375	-3.25	0.08
GW	121	3	4	-4.4317652	-2.6164408	4	-5.9125102	-2.1684843	0.08
GW	122	3	4	-0.85	-4.2	4	-2.3375	-4.625	0.08
GW	123	3	4	-4.4413112	-5.2260889	4	-5.928808	-5.651088	0.08
GW	124	3	4	-0.85	0	4	0.85	0	0.07214272
GW	125	3	4	2.3375	4.625	4	3.08891264	5.97727579	0.08
GW	126	3	4	4.4413144	5.22608983	4	3.08891264	5.97727579	0.08
GW	127	3	4	2.3375	3.25	4	3.06790608	1.88626328	0.08
GW	128	3	4	4.4317652	2.61644078	4	3.06790608	1.88626328	0.08
GW	129	3	4	2.3375	-3.25	4	3.06790608	-1.8862633	0.08
GW	130	3	4	4.4317652	-2.6164408	4	3.06790608	-1.8862633	0.08
GW	131	3	4	2.3375	-4.625	4	3.08891473	-5.9772747	0.08
GW	132	3	4	4.4413144	-5.2260898	4	3.08891473	-5.9772747	0.08
GW	133	3	4	-4.4413144	5.22608983	4	-3.0889126	5.97727579	0.08
GW	134	3	4	-2.3375	4.625	4	-3.0889126	5.97727579	0.08
GW	135	3	4	-4.4317652	2.61644078	4	-3.0679061	1.88626328	0.08
GW	136	3	4	-2.3375	3.25	4	-3.0679061	1.88626328	0.08
GW	137	3	4	-4.4317652	-2.6164408	4	-3.0679061	-1.8862633	0.08
GW	138	3	4	-2.3375	-3.25	4	-3.0679061	-1.8862633	0.08
GW	139	3	4	-4.4413112	-5.2260889	4	-3.0889106	-5.9772769	0.08
GW	140	3	4	-2.3375	-4.625	4	-3.0889106	-5.9772769	0.08
GS	0	0	0.0254		' All in in.
GE	0
LD	5	0	0	0	2.5e7	0
EX	0	124	2	0	1	0
GN	-1
FR	0	1	0	0	585	0

300ohm · 2012-05-25, 02:10 AM

NEC file for the 5.282" Open End Whisker version of the DB2a. This makes the whisker length the same as for the fractal version.

Raw Gain and SWR charts :

NEC file :

Code:

CM DB2 :  AntennasDirect DB-2, converted with 4nec2 on 17-May-12 23:58
CM reflector removed, whiskers flattened
CM whiskers shortened to fractal whisker length of 5.282 inches
CM AGT= 1.0 (0db) at 585 mhz, AutoSeg = 20
CE
GW	200	7	4	0.85	0	4	0.85	3.7	0.08
GW	201	1	4	0.85	3.7	4	0.85	4.2	0.08
GW	202	3	4	0.85	3.7	4	2.3375	3.25	0.08
GW	203	3	4	4.4317652	2.61644078	4	5.91251024	2.1684843	0.08
GW	204	3	4	0.85	4.2	4	2.3375	4.625	0.08
GW	205	3	4	4.4413144	5.22608983	4	5.9510993	5.65745694	0.08
GW	206	7	4	-0.85	0	4	-0.85	3.7	0.08
GW	207	1	4	-0.85	3.7	4	-0.85	4.2	0.08
GW	208	3	4	-0.85	3.7	4	-2.3375	3.25	0.08
GW	209	3	4	-4.4317652	2.61644078	4	-5.9125102	2.1684843	0.08
GW	210	3	4	-0.85	4.2	4	-2.3375	4.625	0.08
GW	211	3	4	-4.4413144	5.22608983	4	-5.9288112	5.65108891	0.08
GW	212	7	4	0.85	0	4	0.85	-3.7	0.08
GW	213	1	4	0.85	-3.7	4	0.85	-4.2	0.08
GW	214	3	4	0.85	-3.7	4	2.3375	-3.25	0.08
GW	215	3	4	4.4317652	-2.6164408	4	5.91251024	-2.1684843	0.08
GW	216	3	4	0.85	-4.2	4	2.3375	-4.625	0.08
GW	217	3	4	4.4413144	-5.2260898	4	5.92881117	-5.6510889	0.08
GW	218	7	4	-0.85	0	4	-0.85	-3.7	0.08
GW	219	1	4	-0.85	-3.7	4	-0.85	-4.2	0.08
GW	220	3	4	-0.85	-3.7	4	-2.3375	-3.25	0.08
GW	221	3	4	-4.4317652	-2.6164408	4	-5.9125102	-2.1684843	0.08
GW	222	3	4	-0.85	-4.2	4	-2.3375	-4.625	0.08
GW	223	3	4	-4.4413112	-5.2260889	4	-5.928808	-5.651088	0.08
GW	224	3	4	-0.85	0	4	0.85	0	0.06
GW	225	5	4	2.3375	4.625	4	4.4413144	5.22608983	0.08
GW	226	5	4	2.3375	3.25	4	4.4317652	2.61644078	0.08
GW	227	5	4	2.3375	-3.25	4	4.4317652	-2.6164408	0.08
GW	228	5	4	2.3375	-4.625	4	4.4413144	-5.2260898	0.08
GW	229	5	4	-4.4413112	-5.2260889	4	-2.3375	-4.625	0.08
GW	230	5	4	-4.4317652	-2.6164408	4	-2.3375	-3.25	0.08
GW	231	5	4	-4.4317652	2.61644078	4	-2.3375	3.25	0.08
GW	232	5	4	-4.4413144	5.22608983	4	-2.3375	4.625	0.08
GS	0	0	0.0254		' All in in.
GE	0
LD	5	0	0	0	2.5e7	0
EX	0	224	2	0	1	0
GN	-1
FR	0	1	0	0	585	0

300ohm · 2012-05-25, 02:20 AM

NEC file for the 5.282" Closed End Whisker version of the DB2a. This makes the whisker length the same as for the fractal version.

Raw Gain and SWR charts :

NEC file :

Code:

CM DB2 :  AntennasDirect DB-2, converted with 4nec2 on 17-May-12 23:58
CM reflector removed, whiskers flattened
CM Whisker length shortened to 5.282" same as fractalized version
CM Closed End Whiskers
CM AGT= 1.0 (0db) at 585 mhz, AutoSeg = 20
CE
GW	300	7	4	0.85	0	4	0.85	3.7	0.08
GW	301	1	4	0.85	3.7	4	0.85	4.2	0.08
GW	302	3	4	0.85	3.7	4	2.3375	3.25	0.08
GW	303	3	4	4.4317652	2.61644078	4	5.91251024	2.1684843	0.08
GW	304	3	4	0.85	4.2	4	2.3375	4.625	0.08
GW	305	3	4	4.4413144	5.22608983	4	5.92881118	5.65108891	0.08
GW	306	7	4	-0.85	0	4	-0.85	3.7	0.08
GW	307	1	4	-0.85	3.7	4	-0.85	4.2	0.08
GW	308	3	4	-0.85	3.7	4	-2.3375	3.25	0.08
GW	309	3	4	-4.4317652	2.61644078	4	-5.9125102	2.1684843	0.08
GW	310	3	4	-0.85	4.2	4	-2.3375	4.625	0.08
GW	311	3	4	-4.4413144	5.22608983	4	-5.9288112	5.65108891	0.08
GW	312	7	4	0.85	0	4	0.85	-3.7	0.08
GW	313	1	4	0.85	-3.7	4	0.85	-4.2	0.08
GW	314	3	4	0.85	-3.7	4	2.3375	-3.25	0.08
GW	315	3	4	4.4317652	-2.6164408	4	5.91251024	-2.1684843	0.08
GW	316	3	4	0.85	-4.2	4	2.3375	-4.625	0.08
GW	317	3	4	4.4413144	-5.2260898	4	5.92881117	-5.6510889	0.08
GW	318	7	4	-0.85	0	4	-0.85	-3.7	0.08
GW	319	1	4	-0.85	-3.7	4	-0.85	-4.2	0.08
GW	320	3	4	-0.85	-3.7	4	-2.3375	-3.25	0.08
GW	321	3	4	-4.4317652	-2.6164408	4	-5.9125102	-2.1684843	0.08
GW	322	3	4	-0.85	-4.2	4	-2.3375	-4.625	0.08
GW	323	3	4	-4.4413112	-5.2260889	4	-5.928808	-5.651088	0.08
GW	324	3	4	-0.85	0	4	0.85	0	0.088
GW	325	5	4	2.3375	4.625	4	4.4413144	5.22608983	0.08
GW	326	5	4	2.3375	3.25	4	4.4317652	2.61644078	0.08
GW	327	5	4	2.3375	-3.25	4	4.4317652	-2.6164408	0.08
GW	328	5	4	2.3375	-4.625	4	4.4413144	-5.2260898	0.08
GW	329	5	4	-4.4413112	-5.2260889	4	-2.3375	-4.625	0.08
GW	330	5	4	-4.4317652	-2.6164408	4	-2.3375	-3.25	0.08
GW	331	5	4	-4.4317652	2.61644078	4	-2.3375	3.25	0.08
GW	332	5	4	-4.4413144	5.22608983	4	-2.3375	4.625	0.08
GW	333	7	4	5.92881118	5.65108891	4	5.91251024	2.1684843	0.08
GW	334	7	4	5.91251024	-2.1684843	4	5.92881117	-5.6510889	0.08
GW	335	7	4	-5.9288112	5.65108891	4	-5.9125102	2.1684843	0.08
GW	336	7	4	-5.9125102	-2.1684843	4	-5.928808	-5.651088	0.08
GS	0	0	0.0254		' All in in.
GE	0
LD	5	0	0	0	2.5e7	0
EX	0	324	2	0	1	0
GN	-1
FR	0	1	0	0	585	0

As you can see, this is the best looking of the bunch, heh.

300ohm · 2012-05-25, 02:43 AM

Closing the ends of the fractalized version helps it quite a bit, but no real noticeable improvement over the plain closed end version of the same size.

Picture:

Raw Gain and SWR charts:

NEC file:

Code:

CM DB2 :  AntennasDirect DB-2, converted with 4nec2 on 17-May-12 23:58
CM reflector removed, whiskers flattened  Fractalized
CM Closed ends
CM AGT= 1.0 (0db) at 585 mhz, AutoSeg = 20
CE
GW	100	7	4	0.85	0	4	0.85	3.7	0.08
GW	101	1	4	0.85	3.7	4	0.85	4.2	0.08
GW	102	3	4	0.85	3.7	4	2.3375	3.25	0.08
GW	103	3	4	4.4317652	2.61644078	4	5.91251024	2.1684843	0.08
GW	104	3	4	0.85	4.2	4	2.3375	4.625	0.08
GW	105	3	4	4.4413144	5.22608983	4	5.9510993	5.65745694	0.08
GW	106	7	4	-0.85	0	4	-0.85	3.7	0.08
GW	107	1	4	-0.85	3.7	4	-0.85	4.2	0.08
GW	108	3	4	-0.85	3.7	4	-2.3375	3.25	0.08
GW	109	3	4	-4.4317652	2.61644078	4	-5.9125102	2.1684843	0.08
GW	110	3	4	-0.85	4.2	4	-2.3375	4.625	0.08
GW	111	3	4	-4.4413144	5.22608983	4	-5.9288112	5.65108891	0.08
GW	112	7	4	0.85	0	4	0.85	-3.7	0.08
GW	113	1	4	0.85	-3.7	4	0.85	-4.2	0.08
GW	114	3	4	0.85	-3.7	4	2.3375	-3.25	0.08
GW	115	3	4	4.4317652	-2.6164408	4	5.91251024	-2.1684843	0.08
GW	116	3	4	0.85	-4.2	4	2.3375	-4.625	0.08
GW	117	3	4	4.4413144	-5.2260898	4	5.92881117	-5.6510889	0.08
GW	118	7	4	-0.85	0	4	-0.85	-3.7	0.08
GW	119	1	4	-0.85	-3.7	4	-0.85	-4.2	0.08
GW	120	3	4	-0.85	-3.7	4	-2.3375	-3.25	0.08
GW	121	3	4	-4.4317652	-2.6164408	4	-5.9125102	-2.1684843	0.08
GW	122	3	4	-0.85	-4.2	4	-2.3375	-4.625	0.08
GW	123	3	4	-4.4413112	-5.2260889	4	-5.928808	-5.651088	0.08
GW	124	3	4	-0.85	0	4	0.85	0	0.086
GW	125	3	4	2.3375	4.625	4	3.08891264	5.97727579	0.08
GW	126	3	4	4.4413144	5.22608983	4	3.08891264	5.97727579	0.08
GW	127	3	4	2.3375	3.25	4	3.06790608	1.88626328	0.08
GW	128	3	4	4.4317652	2.61644078	4	3.06790608	1.88626328	0.08
GW	129	3	4	2.3375	-3.25	4	3.06790608	-1.8862633	0.08
GW	130	3	4	4.4317652	-2.6164408	4	3.06790608	-1.8862633	0.08
GW	131	3	4	2.3375	-4.625	4	3.08891473	-5.9772747	0.08
GW	132	3	4	4.4413144	-5.2260898	4	3.08891473	-5.9772747	0.08
GW	133	3	4	-4.4413144	5.22608983	4	-3.0889126	5.97727579	0.08
GW	134	3	4	-2.3375	4.625	4	-3.0889126	5.97727579	0.08
GW	135	3	4	-4.4317652	2.61644078	4	-3.0679061	1.88626328	0.08
GW	136	3	4	-2.3375	3.25	4	-3.0679061	1.88626328	0.08
GW	137	3	4	-4.4317652	-2.6164408	4	-3.0679061	-1.8862633	0.08
GW	138	3	4	-2.3375	-3.25	4	-3.0679061	-1.8862633	0.08
GW	139	3	4	-4.4413112	-5.2260889	4	-3.0889106	-5.9772769	0.08
GW	140	3	4	-2.3375	-4.625	4	-3.0889106	-5.9772769	0.08
GW	141	7	4	-5.9288112	5.65108891	4	-5.9125102	2.1684843	0.08
GW	142	7	4	-5.9125102	-2.1684843	4	-5.928808	-5.651088	0.08
GW	143	7	4	5.91251024	-2.1684843	4	5.92881117	-5.6510889	0.08
GW	144	7	4	5.9510993	5.65745694	4	5.91251024	2.1684843	0.08
GS	0	0	0.0254		' All in in.
GE	0
LD	5	0	0	0	2.5e7	0
EX	0	124	2	0	1	0
GN	-1
FR	0	1	0	0	585	0

Xauto · 2012-05-25, 07:49 PM

Thank you 300ohm for the comparison work. The fractalized version look cool, but not the best bang for the work put in.

300ohm · 2012-05-26, 12:28 AM

Yep, hard to imagine that something commonly posted on YouTube does a whole lot of nothing, heh.

A Sierpinski triangle fractal used as a closed end bowtie may give enough bandwidth to be used as a combo vhf-uhf bowtie. I'll have to investigate that possibility.

Also, since FAT dipoles (FAT relative to their wavelength) tend to act like bowties (re like the Winegard PR4400), a third order Dragon fractal may be useful. Of course then its not really a bowtie, it just plays one on TV, heh.

300ohm · 2012-05-30, 10:44 PM

Since I was making comparisons of the shortened to 5.282" DB2a, I thought I would give this idea a try:

Picture:

Raw Gain and SWR:

Raw gain goes down a bit and SWR goes up a bit over the plain 2D closed end whisker version, not good.

Beamwidth at 470 mhz increases from 70 degrees to 80 degrees. Beamwidth at 698 mhz remains the same at 60 degrees.

NEC file:

Code:

CM DB2 :  AntennasDirect DB-2, converted with 4nec2 on 17-May-12 23:58
CM reflector removed, whiskers flattened
CM Whisker length shortened to 5.282" same as fractalized version
CM 3D type Closed End Whiskers
CM AGT= 1.0 (0db) at 585 mhz, AutoSeg = 20
CE
GW	300	7	4	0.85	0	4	0.85	3.7	0.08
GW	301	1	4	0.85	3.7	4	0.85	3.95	0.08
GW	337	1	4	0.85	3.95	4	0.85	4.2	0.08
GW	302	3	4	0.85	3.7	4	2.3375	3.25	0.08
GW	303	3	4	4.4317652	2.61644078	4	5.91251024	2.1684843	0.08
GW	304	3	4	0.85	4.2	4	2.3375	4.625	0.08
GW	305	3	4	4.4413144	5.22608983	4	5.92881118	5.65108891	0.08
GW	306	7	4	-0.85	0	4	-0.85	3.7	0.08
GW	307	1	4	-0.85	3.7	4	-0.85	3.95	0.08
GW	350	1	4	-0.85	3.95	4	-0.85	4.2	0.08
GW	308	3	4	-0.85	3.7	4	-2.3375	3.25	0.08
GW	309	3	4	-4.4317652	2.61644078	4	-5.9125102	2.1684843	0.08
GW	310	3	4	-0.85	4.2	4	-2.3375	4.625	0.08
GW	311	3	4	-4.4413144	5.22608983	4	-5.9288112	5.65108891	0.08
GW	312	7	4	0.85	0	4	0.85	-3.7	0.08
GW	318	7	4	-0.85	0	4	-0.85	-3.7	0.08
GW	324	3	4	-0.85	0	4	0.85	0	0.07
GW	325	5	4	2.3375	4.625	4	4.4413144	5.22608983	0.08
GW	326	5	4	2.3375	3.25	4	4.4317652	2.61644078	0.08
GW	331	5	4	-4.4317652	2.61644078	4	-2.3375	3.25	0.08
GW	332	5	4	-4.4413144	5.22608983	4	-2.3375	4.625	0.08
GW	333	3	4	5.92881118	5.65108891	4	5.92066071	3.90978661	0.08
GW	338	3	4	5.92066071	3.90978661	4	5.91251024	2.1684843	0.08
GW	335	3	4	-5.9288112	5.65108891	3.95978661	-5.9206606	3.95	0.08
GW	349	5	3.95978661	-5.9206606	3.95	4	-5.9125102	2.1684843	0.08
GW	339	1	3.75	0.85	3.95	4	0.85	3.95	0.08
GW	340	1	4	0.85	3.95	4.25	0.85	3.95	0.08
GW	341	3	3.75	0.85	3.95	3.3	2.3375	3.95	0.08
GW	342	3	2.66644055	4.43176535	3.95	2.25869803	5.91251032	3.90978661	0.08
GW	343	3	4.25	0.85	3.95	4.675	2.3375	3.95	0.08
GW	344	3	5.27608976	4.44131457	3.95	5.74130236	5.9288115	3.90978661	0.08
GW	345	5	4.675	2.3375	3.95	5.27608976	4.44131457	3.95	0.08
GW	346	5	3.3	2.3375	3.95	2.66644055	4.43176535	3.95	0.08
GW	347	3	5.74130236	5.9288115	3.90978661	4	5.92066071	3.90978661	0.08
GW	348	3	4	5.92066071	3.90978661	2.25869803	5.91251032	3.90978661	0.08
GW	351	1	3.75	-0.85	3.95	4	-0.85	3.95	0.08
GW	352	1	4	-0.85	3.95	4.25	-0.85	3.95	0.08
GW	353	3	3.75	-0.85	3.95	3.3	-2.3375	3.95	0.08
GW	354	3	2.66644094	-4.431765	3.95	2.21848465	-5.9125102	3.95	0.08
GW	355	3	4.25	-0.85	3.95	4.675	-2.3375	3.95	0.08
GW	356	3	5.27609016	-4.4413142	3.95	5.70108898	-5.928811	3.95	0.08
GW	357	5	2.66644094	-4.431765	3.95	3.3	-2.3375	3.95	0.08
GW	358	5	5.27609016	-4.4413142	3.95	4.675	-2.3375	3.95	0.08
GW	359	3	5.70108898	-5.928811	3.95	3.95978661	-5.9206606	3.95	0.08
GW	360	3	3.95978661	-5.9206606	3.95	2.21848465	-5.9125102	3.95	0.08
GW	361	1	4	0.85	-4.2	4	0.85	-3.95	0.08
GW	362	1	4	0.85	-3.95	4	0.85	-3.7	0.08
GW	363	3	4	0.85	-4.2	4	2.3375	-4.65	0.08
GW	364	3	4	4.4317652	-5.2835592	4	5.91251024	-5.7315157	0.08
GW	365	3	4	0.85	-3.7	4	2.3375	-3.275	0.08
GW	366	3	4	4.4413144	-2.6739102	4	5.92881118	-2.2489111	0.08
GW	367	5	4	2.3375	-3.275	4	4.4413144	-2.6739102	0.08
GW	368	5	4	2.3375	-4.65	4	4.4317652	-5.2835592	0.08
GW	369	3	4	5.92881118	-2.2489111	4	5.92066071	-3.9902134	0.08
GW	370	3	4	5.92066071	-3.9902134	4	5.91251024	-5.7315157	0.08
GW	371	1	3.75	0.85	-3.95	4	0.85	-3.95	0.08
GW	372	1	4	0.85	-3.95	4.25	0.85	-3.95	0.08
GW	373	3	3.75	0.85	-3.95	3.3	2.3375	-3.95	0.08
GW	374	3	2.66644055	4.43176535	-3.95	2.25869803	5.91251032	-3.9902134	0.08
GW	375	3	4.25	0.85	-3.95	4.675	2.3375	-3.95	0.08
GW	376	3	5.27608976	4.44131457	-3.95	5.74130236	5.9288115	-3.9902134	0.08
GW	377	5	4.675	2.3375	-3.95	5.27608976	4.44131457	-3.95	0.08
GW	378	5	3.3	2.3375	-3.95	2.66644055	4.43176535	-3.95	0.08
GW	379	3	5.74130236	5.9288115	-3.9902134	4	5.92066071	-3.9902134	0.08
GW	380	3	4	5.92066071	-3.9902134	2.25869803	5.91251032	-3.9902134	0.08
GW	381	1	4	-0.85	-4.2	4	-0.85	-3.95	0.08
GW	382	1	4	-0.85	-3.95	4	-0.85	-3.7	0.08
GW	383	3	4	-0.85	-4.2	4	-2.3375	-4.65	0.08
GW	384	3	4	-4.4317652	-5.2835592	4	-5.9125102	-5.7315157	0.08
GW	385	3	4	-0.85	-3.7	4	-2.3375	-3.275	0.08
GW	386	3	4	-4.4413144	-2.6739102	4	-5.9288112	-2.2489111	0.08
GW	387	5	4	-4.4317652	-5.2835592	4	-2.3375	-4.65	0.08
GW	388	5	4	-4.4413144	-2.6739102	4	-2.3375	-3.275	0.08
GW	389	3	4	-5.9288112	-2.2489111	3.95978661	-5.9206606	-3.95	0.08
GW	390	5	3.95978661	-5.9206606	-3.95	4	-5.9125102	-5.7315157	0.08
GW	391	1	3.75	-0.85	-3.95	4	-0.85	-3.95	0.08
GW	392	1	4	-0.85	-3.95	4.25	-0.85	-3.95	0.08
GW	393	3	3.75	-0.85	-3.95	3.3	-2.3375	-3.95	0.08
GW	394	3	2.66644094	-4.431765	-3.95	2.21848465	-5.9125102	-3.95	0.08
GW	395	3	4.25	-0.85	-3.95	4.675	-2.3375	-3.95	0.08
GW	396	3	5.27609016	-4.4413142	-3.95	5.70108898	-5.928811	-3.95	0.08
GW	397	5	2.66644094	-4.431765	-3.95	3.3	-2.3375	-3.95	0.08
GW	398	5	5.27609016	-4.4413142	-3.95	4.675	-2.3375	-3.95	0.08
GW	399	3	5.70108898	-5.928811	-3.95	3.95978661	-5.9206606	-3.95	0.08
GW	400	3	3.95978661	-5.9206606	-3.95	2.21848465	-5.9125102	-3.95	0.08
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	2.5e7	0
EX	0	324	2	0	1	0
GN	-1
FR	0	1	0	0	585	0

HTPC-Diy · 2012-06-10, 07:25 PM

dasemesti, 300ohm,

Hey guys, sorry I didn't reply sooner. I'm not an expert on antennas I made a few diy ones and read a little about it.

The flexible type antennas seemed to be getting popular so I wanted to see if I could make one cheap that worked.

I made my pattern similar to other fractal antennas I have seen and built out of wire. I was hoping I could find a cheap and easy way to basically print out any fractal antenna at home but that doesn't seem likely. The cheapest way to do it would be to transfer a laser printing to a large PCB and etch it but you lose the flexibility and the transparency. Having large flexible PCB's etched isn't cheap.

Quote:

I wonder how the width of the foil affects the behaviour of the antenna. Did you try to model this antenna with some software?

Before posting to this thread I never tried any antenna modelling software. I've since played around with 4nec2 but I couldn't figure out how to make thick flat wires.

From what I understand these types of signals mainly migrate to the skin of the conductor. At least that's what people say when discussing copper clad wires. I don't know how that would work with this type of antenna? Because of the larger surface area would this be like having a very thick wire?

My first store-bought antenna was an RCA 1650R and I'd sometimes place it in a window. I saw antennas like the Walltenna and Leaf and wanted to see if I could make my own flexible antenna that wouldn't block too much light.

I found some conductive copper tape online which would be a better material to use but I had this stuff laying around and wanted to see if it worked.

Anyone have any idea how to improve the VHF reception on this type of antenna? I tried different ideas in 4nec2 but didn't get far. I'm not very familiar with the program.

300ohm · 2012-06-12, 09:08 PM

Quote:

Before posting to this thread I never tried any antenna modelling software. I've since played around with 4nec2 but I couldn't figure out how to make thick flat wires.

Basically there are two methods with NEC modeling.
1) Use Equivalent Diameter formulas, or

2) Draw the outline of the flat wire, using the thickness as the diameter of the wire. (you of course enter the radius, not diameter in 4nec2) To make it like solid flat stock, you would add middle and/or cross wires every 1/10 wavelength or so. (if the width of the stock is already less than about 1/10 wavelength, then cross wires arent necessary)

In my limited experience, there are only tiny differences in gain and SWR between the two methods, which are so small they probably wouldnt register on a TV signal meter.

Quote:

Anyone have any idea how to improve the VHF reception on this type of antenna? I tried different ideas in 4nec2 but didn't get far.

Try placing some wide reflectors, 28 to 36 inches long, behind the bowties at various distances.

Personne · 2012-07-10, 04:40 PM

Hi. I'm preparing to assemble my ATSC antenna and I have located the main transmitters in my area. They are almost 90° apart so I was wondering if it would be preferable to build two separate arrays, each aimed at their respective emitters and connected in parallel before the preamp or to combine the bays on a single "composite" antenna consisting of a symmetrical number of bays facing alternately each emitter.

I'm trying to avoid a rotor at all cost. I would rather build twice as big an antenna than to give reception priority to some TV set over another.

I have prepared Koch fractal elements of 1st and 2nd order in several copper wire ranging from 10 to 20AWG as well as 10" bow ties segments. I plan to silver-solder them on 10AWG copper risers. I will experiment with qty and placement but obviously, a definitive direction would save me a lot of (fun) time if I should go for one or two distinct arrays from the get-go.

Thanks in advance, Yodas and ObiWans of the electromagnetic radiation domain.

nikiml · 2012-07-10, 04:53 PM

you better post your tvfool (GPS coors alternatively)
The signal strengths info is a very important factor when deciding
what to do. Angles are just not enough.

PS. Some info about your surroundings would also help.

2012-05-17, 03:21 PM	#286
fractalguy Rookie Join Date: Jan 2010 Posts: 2	Hi 300 ohmer-- Can you be a bit more forthcoming on your results? Why not put them up on a website so we can compare them? I'd love to see them and critique them for you. Best wishes, Nathan Cohen
$fractalguy is offline$

2012-05-17, 11:44 PM	#287
300ohm Veteran Join Date: Mar 2008 Location: Somewhere in Delaware on the flat side Posts: 7,006	For the GH, my results are in posts 15 and 17 of this thread. (luckily, those pictures werent deleted when ImageShack changed their terms of service. ) Thanks. __________________ My builds/plans (not the latest models) are located here.

2012-05-26, 12:28 AM	#295
300ohm Veteran Join Date: Mar 2008 Location: Somewhere in Delaware on the flat side Posts: 7,006	Yep, hard to imagine that something commonly posted on YouTube does a whole lot of nothing, heh. A Sierpinski triangle fractal used as a closed end bowtie may give enough bandwidth to be used as a combo vhf-uhf bowtie. I'll have to investigate that possibility. Also, since FAT dipoles (FAT relative to their wavelength) tend to act like bowties (re like the Winegard PR4400), a third order Dragon fractal may be useful. Of course then its not really a bowtie, it just plays one on TV, heh. __________________ My builds/plans (not the latest models) are located here.

2012-07-10, 04:40 PM	#299
Personne Join Date: Dec 2002 Posts: 3	Easy questions for antenna Jedis Hi. I'm preparing to assemble my ATSC antenna and I have located the main transmitters in my area. They are almost 90° apart so I was wondering if it would be preferable to build two separate arrays, each aimed at their respective emitters and connected in parallel before the preamp or to combine the bays on a single "composite" antenna consisting of a symmetrical number of bays facing alternately each emitter. I'm trying to avoid a rotor at all cost. I would rather build twice as big an antenna than to give reception priority to some TV set over another. I have prepared Koch fractal elements of 1st and 2nd order in several copper wire ranging from 10 to 20AWG as well as 10" bow ties segments. I plan to silver-solder them on 10AWG copper risers. I will experiment with qty and placement but obviously, a definitive direction would save me a lot of (fun) time if I should go for one or two distinct arrays from the get-go. Thanks in advance, Yodas and ObiWans of the electromagnetic radiation domain. __________________ ♪♫ You may say I'm a dreamer, but I am not the only one ♪♫

2012-07-10, 04:53 PM	#300
nikiml Join Date: Dec 2008 Location: mississauga, ON Posts: 721	you better post your tvfool (GPS coors alternatively) The signal strengths info is a very important factor when deciding what to do. Angles are just not enough. PS. Some info about your surroundings would also help. __________________ My Antenna designs, Nec optimization scripts and Web nec2 viewer

2012-05-25, 07:49 PM	#294
Xauto Join Date: Sep 2008 Posts: 487	Thank you 300ohm for the comparison work. The fractalized version look cool, but not the best bang for the work put in.

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