Homebrew 4m 70 MHz antennas for amateur ham radio

 

This is a list of designs for any type of 4m 70 MHz homebrew amateur antenna

To refine your search to show only vertical, loop, wire, portable, multiband etc. click refine search for homebrew antennas




Showing matches 1 to 6 of 6

THE HENTENNA

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 st
ations 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 wi
th 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..



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 matchi
ng 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.



Halo antenna for 70Mhz

Based on a commercial model using aluminum tubes from 4 and 6 mm (sold in DIY stores).



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 oh
m feeder, a Delta Match arrangement is used.


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