The Hentenna was developed by Japanese 6 Meter Hams, JE1DEU / JH1FCZ/ JH1YST in the 1970's and can be designed and built for hf thru uhf and possibly beyond! Sizes given are for 6m.
After much experimentation, finally, the antenna was developed with good performance, however, it was difficult to explain why the performance was so good, or how it is worked basically at that time. So it was named Hentenna, "Hen" means "strange" in Japanese.
The antenna has good performance and many advantages and it has become very popular in Japan. Many JA stations make it and enjoy it at home or in the field. Some Japanese 6m beacon stations are using the Hentenna antenna.
EI7BA Multiband Cubical Quad
It covers six bands 20m to 10m on HF and also 6m. It is a Boomless (spider quad gem quad) design. It uses Glassfibre arms (a must). It uses a single coax line to a homebrew antenna switch. From there a seperate feedline goes to each of the Driven Element feedpoints. There is a homebrew Choke Balun at each feedpoint.
Performance
I have no accurate method to measure forward gain but I reckon it is the text book 6 to 7 db. F/B ratio is consistently 5 to 6 S points on my TS850 S meter on all bands 20 - 10m. I don't know how many dBs per S Point for my TS 850 but it is surely at least 3dB per S Point. So this translates to a minimum of 15 dB and arguably as high as 30dB. As with all 2 element Quads It has a wide beamwidth about 60 degrees.
ADDENDUM.. An extra two bands..!
I have added three elements for 6m and 2 elements for the European 4m (70mHz) band to the existing spider, and on a seperate 6ft boom which is clamped to the spider, I have 5 elements for 2m, and 9 elements for 70cms.. A grand total of 11 bands..
A four metre ( 70 MHz ) whip antenna
It seems that every roach pole I’ve bought has added one more whippy top section to my collection of fibre glass that appears to be too thin to properly support an antenna so this project kills two birds with one stone: a four metre portable antenna that uses one of those spare fibreglass fishing pole sections.
The physical design is based on the many portable and mobile whip antennas available for both HF and VHF, with a durable, flexible vertical mounted directly onto a coaxial connector at the feed point. Its dimensions are determined by the materials available – the length of the fishing rod section being a key factor – and the tuning of the antenna.
Vertical half-wave aerials for 4m
For vertical use, it is much more mechanically convenient to end-feed an antenna: this will allow it to be mounted higher, and avoids distortion of its omnidirectional polar pattern by the nearby mast. The disadvantage is that the end-feed point is high-impedance, and so requires a high-Q (i.e. narrow bandwidth) circuit to match it to 50-ohm feeder. However, as the FM section of the 4m band is such a narrow allocation (only some 0.4% of its frequency), this narrow bandwidth matching is no disadvantage (as it would be on say 6m, where an aerial may be required to operate over a 4% frequency range).
A centre-fed "co-axial" dipole for 4m
In contrast to the end-fed designs, which can be difficult to set up because of their narrow bandwidth, this alternative uses a low-impedance centre-feed, and hence offers a broader bandwidth.
In this design, the radiating half-wave section is formed from the centre conductor of a piece of co-axial cable, which is fed via two sections of its outer braiding which have been left in place.
7 Element 4M (70MHz) Beam By Paul Graver M1CCZ
This 7 element beam, designed around a centre frequency of 70.25 provides approximately 12dBi gain with a F/B ratio of 30dB.
All of the elements are 13mm diameter aluminium tube mounted through a 50mm diameter aluminium boom, including the driven element, which is not split or insulated from the boom. The overall boom length is about 5 1/2 metres. To match the beam to the 50 ohm feeder, a Delta Match arrangement is used.
