
<PAGE>   1



                                                                    Exhibit 4(c)


                           CERTIFICATE OF DESIGNATION

                                       of

                          SERIES C JUNIOR PARTICIPATING
                                 PREFERRED STOCK

                                       of

                               ALLEN TELECOM INC.

                         (Pursuant to Section 151 of the
                General Corporation Law of the State of Delaware)


         Allen Telecom Inc., a corporation organized and existing under the
General Corporation Law of the State of Delaware (hereinafter called the
"Company"), DOES HEREBY CERTIFY:

         That, pursuant to authority vested in the Board of Directors of the
Company by its Restated Certificate of Incorporation, as amended, and pursuant
to the provisions of Section 151 of the General Corporation Law, the Board of
Directors of the Company has adopted the following resolution providing for the
issuance of a series of Preferred Stock:

         RESOLVED, that pursuant to the authority expressly granted to and
vested in the Board of Directors of the Company (hereinafter called the "Board
of Directors" or the "Board") by the Restated Certificate of Incorporation of
the Company, as amended, a series of Preferred Stock, without par value (the
"Preferred Stock"), of the Company be, and it hereby is, created, and that the
designation and amount thereof and the powers, designations, preferences and
relative, participating, optional and other special rights of the shares of such
series, and the qualifications, limitations or restrictions thereof are as
follows:

                            I. Designation and Amount
                               ----------------------

         The shares of such series will be designated as Series C Junior
Participating Preferred Stock (the "Series C Preferred") and the number of
shares constituting the Series C Preferred is 500,000. Such number of shares may
be increased or decreased by resolution of the Board; PROVIDED, HOWEVER, that no
decrease will reduce the number of shares of Series C Preferred to a number less
than the number of shares then outstanding plus the number of shares reserved
for issuance upon the exercise of outstanding options, rights or warrants or
upon the conversion of any outstanding securities issued by the Company
convertible into Series C Preferred.



<PAGE>   2



                         II. Dividends and Distributions
                             ---------------------------

         (a) Subject to the rights of the holders of any shares of any series of
Preferred Stock ranking prior to the Series C Preferred with respect to
dividends, the holders of shares of Series C Preferred, in preference to the
holders of Common Stock, par value $1.00 per share (the "Common Stock"), of the
Company, and of any other junior stock, will be entitled to receive, when, as
and if declared by the Board out of funds legally available for the purpose,
dividends payable in cash (except as otherwise provided below) on such dates as
are from time to time established for the payment of dividends on the Common
Stock (each such date being referred to herein as a "Dividend Payment Date"),
commencing on the first Dividend Payment Date after the first issuance of a
share or fraction of a share of Series C Preferred (the "First Dividend Payment
Date"), in an amount per share (rounded to the nearest cent) equal to the
greater of (i) $1.00 or (ii) subject to the provision for adjustment hereinafter
set forth, one hundred times the aggregate per share amount of all cash
dividends, and one hundred times the aggregate per share amount (payable in
kind) of all non-cash dividends, other than a dividend payable in shares of
Common Stock or a subdivision of the outstanding shares of Common Stock (by
reclassification or otherwise), declared on the Common Stock since the
immediately preceding Dividend Payment Date or, with respect to the First
Dividend Payment Date, since the first issuance of any share or fraction of a
share of Series C Preferred. In the event that the Company at any time (i)
declares a dividend on the outstanding shares of Common Stock payable in shares
of Common Stock, (ii) subdivides the outstanding shares of Common Stock, (iii)
combines the outstanding shares of Common Stock into a smaller number of shares,
or (iv) issues any shares of its capital stock in a reclassification of the
outstanding shares of Common Stock (including any such reclassification in
connection with a consolidation or merger in which the Company is the continuing
or surviving corporation), then, in each such case and regardless of whether any
shares of Series C Preferred are then issued or outstanding, the amount to which
holders of shares of Series C Preferred would otherwise be entitled immediately
prior to such event under clause (ii) of the preceding sentence will be adjusted
by multiplying such amount by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

         (b) The Company will declare a dividend on the Series C Preferred as
provided in the immediately preceding paragraph immediately after it declares a
dividend on the Common Stock (other than a dividend payable in shares of Common
Stock). Each such dividend on the Series C Preferred will be payable immediately
prior to the time at which the related dividend on the Common Stock is payable.

         (c) Dividends will accrue on outstanding shares of Series C Preferred
from the Dividend Payment Date next preceding the date of issue of such shares,
unless (i) the date of issue of such shares is prior to the record date for the
First Dividend Payment Date, in which case dividends on such shares will accrue
from the date of the first issuance of a share of Series C Preferred or (ii) the
date of issue is a Dividend Payment Date or is a date after the record date for
the determination of holders of shares of Series C Preferred entitled to receive
a dividend and before such Dividend Payment Date, in either of which events such
dividends will accrue from such Dividend Payment Date. Accrued but unpaid
dividends will cumulate from the applicable

                                        2

<PAGE>   3



Dividend Payment Date but will not bear interest. Dividends paid on the shares
of Series C Preferred in an amount less than the total amount of such dividends
at the time accrued and payable on such shares will be allocated pro rata on a
share-by-share basis among all such shares at the time outstanding. The Board
may fix a record date for the determination of holders of shares of Series C
Preferred entitled to receive payment of a dividend or distribution declared
thereon, which record date will be not more than 60 calendar days prior to the
date fixed for the payment thereof.

                               III. Voting Rights
                                    -------------

         The holders of shares of Series C Preferred will have the following
voting rights:

                  (a) Subject to the provision for adjustment hereinafter set
         forth, each share of Series C Preferred will entitle the holder thereof
         to one hundred votes on all matters submitted to a vote of the
         stockholders of the Company. In the event the Company at any time (i)
         declares a dividend on the outstanding shares of Common Stock payable
         in shares of Common Stock, (ii) subdivides the outstanding shares of
         Common Stock, (iii) combines the outstanding shares of Common Stock
         into a smaller number of shares, or (iv) issues any shares of its
         capital stock in a reclassification of the outstanding shares of Common
         Stock (including any such reclassification in connection with a
         consolidation or merger in which the Company is the continuing or
         surviving corporation), then, in each such case and regardless of
         whether any shares of Series C Preferred are then issued or
         outstanding, the number of votes per share to which holders of shares
         of Series C Preferred would otherwise be entitled immediately prior to
         such event will be adjusted by multiplying such number by a fraction,
         the numerator of which is the number of shares of Common Stock
         outstanding immediately after such event and the denominator of which
         is the number of shares of Common Stock that were outstanding
         immediately prior to such event.

                  (b) Except as otherwise provided herein, in any other
         Preferred Stock Designation creating a series of Preferred Stock or any
         similar stock, or by law, the holders of shares of Series C Preferred
         and the holders of shares of Common Stock and any other capital stock
         of the Company having general voting rights will vote together as one
         class on all matters submitted to a vote of stockholders of the
         Company.

                  (c) Except as set forth in the Restated Certificate of
         Incorporation, as amended, or herein, or as otherwise provided by law,
         holders of shares of Series C Preferred will have no voting rights.

                            IV. Certain Restrictions
                                --------------------

         (a) Whenever dividends or other dividends or distributions payable on
the Series C Preferred are in arrears, thereafter and until all accrued and
unpaid dividends and distributions, whether or not declared, on shares of Series
C Preferred outstanding have been paid in full, the Company will not:


                                        3

<PAGE>   4



                     (i) Declare or pay dividends, or make any other
         distributions, on any shares of stock ranking junior (either as to
         dividends or upon liquidation, dissolution or winding up) to the shares
         of Series C Preferred;

                    (ii) Declare or pay dividends, or make any other
         distributions, on any shares of stock ranking on a parity (either as to
         dividends or upon liquidation, dissolution, or winding up) with the
         shares of Series C Preferred, except dividends paid ratably on the
         shares of Series C Preferred and all such parity stock on which
         dividends are payable or in arrears in proportion to the total amounts
         to which the holders of all such shares are then entitled;

                   (iii) Redeem, purchase or otherwise acquire for consideration
         shares of any stock ranking junior (either as to dividends or upon
         liquidation, dissolution or winding up) to the shares of Series C
         Preferred; PROVIDED, HOWEVER, that the Company may at any time redeem,
         purchase or otherwise acquire shares of any such junior stock in
         exchange for shares of any stock of the Company ranking junior (either
         as to dividends or upon dissolution, liquidation or winding up) to the
         shares of Series C Preferred; or

                    (iv) Redeem, purchase or otherwise acquire for consideration
         any shares of Series C Preferred, or any shares of stock ranking on a
         parity with the shares of Series C Preferred, except in accordance with
         a purchase offer made in writing or by publication (as determined by
         the Board) to all holders of such shares upon such terms as the Board,
         after consideration of the respective annual dividend rates and other
         relative rights and preferences of the respective series and classes,
         may determine in good faith will result in fair and equitable treatment
         among the respective series or classes.

         (b) The Company will not permit any majority-owned subsidiary of the
Company to purchase or otherwise acquire for consideration any shares of stock
of the Company unless the Company could, under paragraph (a) of this Article IV,
purchase or otherwise acquire such shares at such time and in such manner.

                              V. Reacquired Shares
                                 -----------------

         Any shares of Series C Preferred purchased or otherwise acquired by the
Company in any manner whatsoever will be retired and canceled promptly after the
acquisition thereof. All such shares will upon their cancellation become
authorized but unissued shares of Preferred Stock and may be reissued as part of
a new series of Preferred Stock subject to the conditions and restrictions on
issuance set forth herein, in the Restated Certificate of Incorporation of the
Company, as amended, or in any other Preferred Stock Designation creating a
series of Preferred Stock or any similar stock or as otherwise required by law.

                   VI. Liquidation, Dissolution or Winding Up
                       --------------------------------------

         Upon any liquidation, dissolution or winding up of the Company, no
distribution will be made (a) to the holders of shares of stock ranking junior
(either as to dividends or upon liquidation, dissolution, or winding up) to the
shares of Series C Preferred unless, prior thereto,


                                        4

<PAGE>   5



the holders of shares of Series C Preferred have received $100 per share, plus
an amount equal to accrued and unpaid dividends and distributions thereon,
whether or not declared, to the date of such payment; PROVIDED, HOWEVER, that
the holders of shares of Series C Preferred will be entitled to receive an
aggregate amount per share, subject to the provision for adjustment hereinafter
set forth, equal to one hundred times the aggregate amount to be distributed per
share to holders of shares of Common Stock or (b) to the holders of shares of
stock ranking on a parity (either as to dividends or upon liquidation,
dissolution, or winding up) with the shares of Series C Preferred, except
distributions made ratably on the shares of Series C Preferred and all such
parity stock in proportion to the total amounts to which the holders of all such
shares are entitled upon such liquidation, dissolution, or winding up. In the
event the Company at any time (i) declares a dividend on the outstanding shares
of Common Stock payable in shares of Common Stock, (ii) subdivides the
outstanding shares of Common Stock, (iii) combines the outstanding shares of
Common Stock into a smaller number of shares, or (iv) issues any shares of its
capital stock in a reclassification of the outstanding shares of Common Stock
(including any such reclassification in connection with a consolidation or
merger in which the Company is the continuing or surviving corporation), then,
in each such case and regardless of whether any shares of Series C Preferred are
then issued or outstanding, the aggregate amount to which each holder of shares
of Series C Preferred would otherwise be entitled immediately prior to such
event under the proviso in clause (a) of the preceding sentence will be adjusted
by multiplying such amount by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

                        VII. Consolidation, Merger, Etc.
                             ---------------------------

         In the event that the Company enters into any consolidation, merger,
combination or other transaction in which the shares of Common Stock are
exchanged for or changed into other stock or securities, cash and/or any other
property, then, in each such case, each share of Series C Preferred will at the
same time be similarly exchanged for or changed into an amount per share,
subject to the provision for adjustment hereinafter set forth, equal to one
hundred times the aggregate amount of stock, securities, cash and/or any other
property (payable in kind), as the case may be, into which or for which each
share of Common Stock is changed or exchanged. In the event the Company at any
time (a) declares a dividend on the outstanding shares of Common Stock payable
in shares of Common Stock, (b) subdivides the outstanding shares of Common
Stock, (c) combines the outstanding shares of Common Stock into a smaller number
of shares, or (d) issues any shares of its capital stock in a reclassification
of the outstanding shares of Common Stock (including any such reclassification
in connection with a consolidation or merger in which the Company is the
continuing or surviving corporation), then, in each such case and regardless of
whether any shares of Series C Preferred are then issued or outstanding, the
amount set forth in the preceding sentence with respect to the exchange or
change of shares of Series C Preferred will be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.


                                        5

<PAGE>   6



                                VIII. Redemption
                                      ----------

         The shares of Series C Preferred are not redeemable.

                                    IX. Rank
                                        ----

         The Series C Preferred rank, with respect to the payment of dividends
and the distribution of assets, junior to all other series of the Company's
Preferred Stock.

                                  X. Amendment
                                     ---------

         Notwithstanding anything contained in the Restated Certificate of
Incorporation of the Company, as amended, to the contrary and in addition to any
other vote required by applicable law, the Restated Certificate of Incorporation
of the Company, as amended, may not be amended in any manner that would
materially alter or change the powers, preferences or special rights of the
Series C Preferred so as to affect them adversely without the affirmative vote
of the holders of at least 80% of the outstanding shares of Series C Preferred,
voting together as a single series.

         IN WITNESS WHEREOF, this Certificate of Designation is executed on
behalf of the Company by its President and attested by its Secretary this 6th
day of January, 1998.


                                          /s/ Robert G. Paul
                                          --------------------------------
                                          Robert G. Paul
                                          President


Attest:

/s/ McDara P. Folan, III
---------------------------------
McDara P. Folan, III
Secretary


                                        6


