• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

Folded dipole array question

Status
Not open for further replies.

mvrx

Member
Joined
Mar 29, 2012
Messages
23
Hi guys,

I just got a UHF-DP-ARRAY-4/h antenna (Products) and plan on using it on a UHF DMR repeater. It will be side mounted on a large tower and I want to obtain the widest radius of radiation.

While the "Spacing from mast" is easy to calculate (1/2WL, 1/4WL and 3/8WL @ freq.), I am not sure about "Spacing between dipoles". On the PDF under the "TYPICAL RADIATION PATTERN" the spacing is given as 0.76 or 0.78WL. Searching for info about this type of array but different brands, I saw that the vertical spacing between dipoles is usually stated as 1WL so I'm confused, hence the following questions :

1 - Is the 0.78WL critical? If I get it wrong (.76 vs .78) it will affect the vertical beamwidth only?
2 - 3/8WL for "spacing from mast" vs 1/4WL will give me wider radius but sacrifice some gain?
3 - What about the mast? What should be the optimal distance from the tower?

Thank you!
Raz
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,984
Location
So Cal - Richardson, TX - Tewksbury, MA
If all the dipoles will be lined up facing the same direction you can choose the best spacing from the mast from the mfrs instruction sheet to give whatever pattern is best for you. I usually run this type of antenna in an omni pattern where each dipole is 45deg offset from the next, or imagine the top dipole pointing north, next one down pointing east, next south and bottom pointing west. For that I think 1/4 wavelength spacing from the mast is best.

For omni mode with dipoles arranged around compass headings, I would use an arm off the tower to get the antenna as far as possible away from the tower. 4ft would be the minimum in my opinion and more is better to keep the tower influence down.

For vertical spacing I would use whatever the mfr suggests and it can be critical and affect the vertical pattern and gain. To find .78 wavelength go online to a wavelength calculator, enter your operating frequency to get a length, then multiply by .78 to get your vertical spacing.
prcguy

Hi guys,

I just got a UHF-DP-ARRAY-4/h antenna (Products) and plan on using it on a UHF DMR repeater. It will be side mounted on a large tower and I want to obtain the widest radius of radiation.

While the "Spacing from mast" is easy to calculate (1/2WL, 1/4WL and 3/8WL @ freq.), I am not sure about "Spacing between dipoles". On the PDF under the "TYPICAL RADIATION PATTERN" the spacing is given as 0.76 or 0.78WL. Searching for info about this type of array but different brands, I saw that the vertical spacing between dipoles is usually stated as 1WL so I'm confused, hence the following questions :

1 - Is the 0.78WL critical? If I get it wrong (.76 vs .78) it will affect the vertical beamwidth only?
2 - 3/8WL for "spacing from mast" vs 1/4WL will give me wider radius but sacrifice some gain?
3 - What about the mast? What should be the optimal distance from the tower?

Thank you!
Raz
 

mvrx

Member
Joined
Mar 29, 2012
Messages
23
prcguy thanks! Actually this is the tower :

It's 114ft tall and the antenna will be mounted close to the top, 5ft away from the tower arm.
I don't need an omni pattern since the area behind the tower doesn't matter but the one facing the antenna would be great to have >180 degrees. Dipoles will be arranged all facing the same direction.
For this to be achieved will 3/8WL work better than 1/4WL for the spacing from mast of the dipoles?

Thank you.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,984
Location
So Cal - Richardson, TX - Tewksbury, MA
Looks like 1/4 wave spacing will give a little more gain across about 150deg swath where 3/8 wave is a little more consistent over 180deg but with a little less gain. Use whatever best fits your needs.
prcguy


prcguy thanks! Actually this is the tower :

It's 114ft tall and the antenna will be mounted close to the top, 5ft away from the tower arm.
I don't need an omni pattern since the area behind the tower doesn't matter but the one facing the antenna would be great to have >180 degrees. Dipoles will be arranged all facing the same direction.
For this to be achieved will 3/8WL work better than 1/4WL for the spacing from mast of the dipoles?

Thank you.
 
Status
Not open for further replies.
Top