HB9CV med flere elementer til 2-meter?

Nogle idéer, tegninger, inspiration?
Bygges de øvrige elementer som passive (ligesom en alm. yagi) eller gør man elementerne aktive (evt. i stil med dén måde, som 2-element originalversionen er udført på)?

Hilsen
Lars
OZ0LTT

Svar til #1:

Det er før set at en HB9CV er blevet forsynet med en eller flere direktorer. Spørgsmålet er så om det stadig er en HB9CV.

Princippet er at både driver-elementet og reflektor i en HB9CV bliver fødet med et faseforskudt signal og opnår derved en anelse bedre forstærkning/retningsvirkning end i en alm 2elemt Yagi.

Desværre ingen tegninger og henvisninger på stående fod.

Vy 73 de oz1etp/Lars

Svar til #1:
Her er lidt om en 3 elm. version:

http://radiosonde.eu/RS08/RS08E22.html

https://home.kpn.nl/fewe17oy/antenna/hb9cv.htm

vy 73

Ye Olde Radio Engineer

Svar til #1:

Godt spørgsmål: Ja og ja!

.

LPDA; logaritmisk periodisk dipol antenne - hvis alle elementer skal senderfødes (flerelementet HB9CV):
https://en.wikipedia.org/wiki/Log-periodic_anten na

.

Eller hybrid LPDA-Yagi med Yagi-direktorer - fx kaldet Log Periodic Yagi, logaritmisk periodisk Yagi, log periodisk Yagi, log-Yagi, LPY eller LPDA-Yagi - og den har stadig den ønskede designbåndbredde:


Original kilde:

2 YAGI ANTENNA'S FROM G3SYC:
A 6 ELEMENT LOG PERIODIC YAGI FOR 6 METRES (kan laves til 2 meter):
https://web.archive.org/web/20021018085422/http: //www.6mdx.eurobell.co.uk/antg3syc.html
Citat: "...
13dBd [front]
...
-10dBd [=-23dBd+13dBd back]
..."
( fundet via denne link og så gravet frem i webarchive: https://www.qsl.net/vu2wap/antenna/projects.html )


kopi:

13dBd
6 Element Log Periodic Yagi for 6 meters (kan laves til 2 meter):
http://www.iw5edi.com/ham-radio/?6-element-log- periodic-yagi-for-6-meters%2C70
backup:
https://web.archive.org/web/20190419153517/http: //www.iw5edi.com/ham-radio/?6-element-lo g-periodic-yagi-for-6-meters%2C70

.


log-yagi simplified.
A 12-foot (boom) antenna achieves 11-dB gain on 10 meters [6 elementer; 3 elementer log-celle, en reflektor - og 2 direktorer]:
https://worldradiohistory.com/Archive-DX/Ham%20R adio/80s/Ham-Radio-198305.pdf
https://web.archive.org/web/20220329051551/https ://worldradiohistory.com/Archive-DX/Ham% 20Radio/80s/Ham-Radio-198305.pdf
Citat: "...
Apparent gain follows the design gain quite closely in Log-Yagi arrays. On long-haul paths of over 3000 miles, a comparison with a reference dipole yields results that are quite close to those derived by computations using the curves. The large capture area and non-symmetrical vertical pattern are no doubt contributors to its ability on such paths.
..."


side 20:
https://worldradiohistory.com/Archive-DX/Ham%20R adio/80s/Ham-Radio-198909.pdf
https://web.archive.org/web/20220329052913/https ://worldradiohistory.com/Archive-DX/Ham% 20Radio/80s/Ham-Radio-198909.pdf
Citat: "...
Peter Rhodes, K4EWG, and J. R. Painter, W4BBF1 have described an interesting hybrid antenna.8 It's designed for single band use, and combines an LPD cell with parasitic elements. The designers claim this configuration achieves higher gain and greater directivity over a single Amateur band than either an LPD or a Yagi array alone (see Figure 5). Best of all, these attributes are achieved with a boom comparable in length to that of a small Yagi. They claim a gain figure of 11.5 dBd for a 14-MHz LPY with a boom length of 26.5 feet. [dvs kortere end følgende ved 2 meter: 2,65 fod = 81cm ! ] A four-element Yagi on the same boom would provide about 7.3-dBd gain. This gives an apparent signal advantage of about 4 dB for the LPY array over the Yagi. It sounds almost too good to be true!
..."


UA9BA Antennas, Hybrids of LPDA and Yagi Udas:
https://dxnews.com/ua9ba-lpda-hybrids/
https://web.archive.org/web/20220128044435/https ://dxnews.com/ua9ba-lpda-hybrids/
Citat: "...
My first LPDA project was student's work in 1976 on practical and theoretical issues of building narrow banded Log-Yagis. My work was partialy based on materials from article in Nov. 1973 issue of QST mag. by Peter Rhodes K4EWG on Log-Yagi for 20m band.
...
I and my teammates built an 8 element 20 meter band Log-Yagi with 4 element log-cell, 3 parasitic directors and 1 reflector in 1978.
..."

The Monoband Log-Cell Yagi Revisited - Antentop:
http://www.antentop.org/w4rnl.001/logc1.html
https://web.archive.org/web/20181229203730/http: //www.antentop.org/w4rnl.001/logc1.html
Citat: "...
Although the design had been known earlier, the monoband log-cell Yagi array was briefly popular in amateur literature in the late 1970s and early 1980s, largely through the work of Rhodes, K4EWG, Painter, W4BBP, and Zimmer, K4JZB.1 Versions can be found in Orr and Cowan's Beam Antenna Handbook, and in the ARRL Antenna Book. In recent times, interest in the design has renewed.
...
With the renewed interest in the antenna, many potential users read the older claims as if they would stand up to modern scrutiny. However, to date, I have seen no re-evaluation of the log-cell Yagi design. Modern analytical tools, such as computer modeling, offer us a chance to better understand the antenna and to assess its place among monoband antennas used by amateurs.
..."

Svar til #1 og #3:

Denne tegning tror jeg er forkert - det øverste gamma-match (0,92) skal flyttes til venstre:
https://home.kpn.nl/fewe17oy/antenna/hb9cv.htm

Det er muligt at man kan fortsætte med HB9CV fødedipoler med gamma-match, hvis man skifter side for hver anden gamma-match - og hver gamma match får en seriekondensator.

Antennens fødepunkt er ved det korteste element.

Det korteste element tager de højeste frekvenser; det næste lidt lavere frekvenser osv. Kondensatoren burde medvirke til højpasfilterering?

Formentlig kan det længste element undvære en kondensator, da der ikke er brug for højpasfiltrering (der er ikke længere elementer bag det sidste element).